Articoli di riviste: "GaN-on-Si"

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Jang, Soohwan, F. Ren, S. J. Pearton, B. P. Gila, M. Hlad, C. R. Abernathy, Hyucksoo Yang et al. "Si-diffused GaN for enhancement-mode GaN mosfet on si applications". Journal of Electronic Materials 35, n. 4 (aprile 2006): 685–90. http://dx.doi.org/10.1007/s11664-006-0121-1.

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Zhou, W. L., F. Namavar, P. C. Colter, M. Yoganathan, M. W. Leksono e J. I. Pankove. "Characterization of GaN Grown on SiC on Si/SiO2/Si by Metalorganic Chemical Vapor Deposition". Journal of Materials Research 14, n. 4 (aprile 1999): 1171–74. http://dx.doi.org/10.1557/jmr.1999.0155.

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SiC (3C-SiC) was grown on the top Si layer of SIMOX (Si/SiO2/Si) by carbonization followed by chemical vapor deposition (CVD). Subsequently, GaN was deposited on the SiC by metalorganic (MO) CVD to produce a GaN/SiC/Si/SiO2/Si multilayer structure. This multilayer film was investigated by conventional transmission electron microscopy (TEM) and high-resolution (HR) TEM from cross-sectional view. The GaN layer was found to consist of predominately hexagonal gallium nitride (h-GaN), and a small fraction of cubic GaN (c-GaN) crystallites. The orientation relationship between most of the h-GaN grains and SiC (3C-SiC) was found to be (0001)Ga N||s(111)SiC; [1120]GaN||[110]SiC, while most of the c-GaN grains had an orientation relationship (001)GaN||(001)SiC; [110]GaN||[110]SiC with respect to 3C-SiC substrate. The hexagonal grains of GaN were found to grow as two variants. The defects in both h-GaN and c-GaN are also discussed.

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Chowdhury, Nadim, Jori Lemettinen, Qingyun Xie, Yuhao Zhang, Nitul S. Rajput, Peng Xiang, Kai Cheng, Sami Suihkonen, Han Wui Then e Tomas Palacios. "p-Channel GaN Transistor Based on p-GaN/AlGaN/GaN on Si". IEEE Electron Device Letters 40, n. 7 (luglio 2019): 1036–39. http://dx.doi.org/10.1109/led.2019.2916253.

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Schulze, F., A. Dadgar, J. Bläsing e A. Krost. "GaN heteroepitaxy on Si(001)". Journal of Crystal Growth 272, n. 1-4 (dicembre 2004): 496–99. http://dx.doi.org/10.1016/j.jcrysgro.2004.08.065.

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Krost, A., e A. Dadgar. "GaN-Based Devices on Si". physica status solidi (a) 194, n. 2 (dicembre 2002): 361–75. http://dx.doi.org/10.1002/1521-396x(200212)194:2<361::aid-pssa361>3.0.co;2-r.

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Dadgar, Armin. "Sixteen years GaN on Si". physica status solidi (b) 252, n. 5 (25 febbraio 2015): 1063–68. http://dx.doi.org/10.1002/pssb.201451656.

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7

Hsu, Lung-Hsing, Yung-Yu Lai, Po-Tsung Tu, Catherine Langpoklakpam, Ya-Ting Chang, Yu-Wen Huang, Wen-Chung Lee et al. "Development of GaN HEMTs Fabricated on Silicon, Silicon-on-Insulator, and Engineered Substrates and the Heterogeneous Integration". Micromachines 12, n. 10 (27 settembre 2021): 1159. http://dx.doi.org/10.3390/mi12101159.

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GaN HEMT has attracted a lot of attention in recent years owing to its wide applications from the high-frequency power amplifier to the high voltage devices used in power electronic systems. Development of GaN HEMT on Si-based substrate is currently the main focus of the industry to reduce the cost as well as to integrate GaN with Si-based components. However, the direct growth of GaN on Si has the challenge of high defect density that compromises the performance, reliability, and yield. Defects are typically nucleated at the GaN/Si heterointerface due to both lattice and thermal mismatches between GaN and Si. In this article, we will review the current status of GaN on Si in terms of epitaxy and device performances in high frequency and high-power applications. Recently, different substrate structures including silicon-on-insulator (SOI) and engineered poly-AlN (QST®) are introduced to enhance the epitaxy quality by reducing the mismatches. We will discuss the development and potential benefit of these novel substrates. Moreover, SOI may provide a path to enable the integration of GaN with Si CMOS. Finally, the recent development of 3D hetero-integration technology to combine GaN technology and CMOS is also illustrated.

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Liang, Fangzhou, Wen Chen, Meixin Feng, Yingnan Huang, Jianxun Liu, Xiujian Sun, Xiaoning Zhan, Qian Sun, Qibao Wu e Hui Yang. "Effect of Si Doping on the Performance of GaN Schottky Barrier Ultraviolet Photodetector Grown on Si Substrate". Photonics 8, n. 2 (23 gennaio 2021): 28. http://dx.doi.org/10.3390/photonics8020028.

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GaN Schottky barrier ultraviolet photodetectors with unintentionally doped GaN and lightly Si-doped n−-GaN absorption layers were successfully fabricated, respectively. The high-quality GaN films on the Si substrate both have a fairly low dislocation density and point defect concentration. More importantly, the effect of Si doping on the performance of the GaN-on-Si Schottky barrier ultraviolet photodetector was studied. It was found that light Si doping in the absorption layer can significantly increase the responsivity under reverse bias, which might be attributed to the persistent photoconductivity that originates from the lowering of the Schottky barrier height. In addition, the devices with unintentionally doped GaN demonstrated a relatively high-speed photo response. We briefly studied the mechanism of changes in Schottky barrier, dark current and the characteristic of response time.

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Кукушкин, С. А., А. М. Мизеров, А. С. Гращенко, А. В. Осипов, Е. В. Никитина, С. Н. Тимошнев, А. Д. Буравлев e М. С. Соболев. "Фотоэлектрические свойства слоев GaN, выращенных методом молекулярно-лучевой эпитаксии с плазменной активацией на подложках Si(111) и эпитаксиальных слоях SiC на Si(111)". Физика и техника полупроводников 53, n. 2 (2019): 190. http://dx.doi.org/10.21883/ftp.2019.02.47097.8915.

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AbstractThe photoelectric properties of GaN/SiC/Si(111) and GaN/Si(111) heterostructures grown by plasma-assisted molecular-beam epitaxy under the same growth conditions on identical silicon substrates, but with different buffer layers, are experimentally investigated. The GaN/SiC/Si(111) structure is formed on a Si substrate with the SiC buffer layer grown by a new atom-substitution technique and the GaN/Si(111) structure, on a Si substrate subjected to pre-epitaxial plasma nitridation. The significant effect of carbon-vacancy clusters contained in the SiC layer on the growth of the GaN layer and its optical and photoelectric properties is found. It is experimentally established that the GaN/SiC/Si(111) heterostructure has a higher photosensitivity than the GaN/Si(111) heterostructure. In the GaN/SiC/Si(111) heterostructure, the coexistence of two oppositely directed p – n junctions is observed. One p – n junction forms at the SiC/Si interface and the other, at the GaN/SiC interface. It is shown that the occurrence of an electric barrier in the GaN/Si(111) heterostructure at the GaN/Si(111) heterointerface is caused by the formation of a thin silicon-nitride transition layer during pre-epitaxial plasma nitridation of the Si(111) substrate.

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MANOHAR, S., A. PHAM, J. BROWN, R. BORGES e K. LINTHICUM. "MICROWAVE GaN-BASED POWER TRANSISTORS ON LARGE-SCALE SILICON WAFERS". International Journal of High Speed Electronics and Systems 13, n. 01 (marzo 2003): 265–75. http://dx.doi.org/10.1142/s0129156403001600.

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This paper presents the development of microwave Gallium nitride (GaN) heterostructure field-effect transistors (HFETs) on silicon (Si). GaN-on-Si provides a low-cost manufacturable platform that could lead to the commercialization of GaN-based power devices for wireless applications. Small periphery GaN high electron mobility transistors (HEMTs) on Si exhibited a maximum drain current of 900mA/mm, a peak gm of 300 mS/mm, and a microwave output power density of 1.5 W/mm at 2 GHz. Microwave characterization and device modeling of GaN HEMTs on Si are discussed.

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Kang, T. W., S. H. Park e T. W. Kim. "Improvement of the crystallinity of GaN epitaxial layers grown on porous Si (100) layers by using a two-step method". Journal of Materials Research 15, n. 12 (dicembre 2000): 2602–5. http://dx.doi.org/10.1557/jmr.2000.0373.

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A new approach was used for combining GaN and porous Si with the goal of producing high-quality GaN epitaxial layers for optoelectronic integrated circuit devices based on Si substrates. Reflection high-energy electron diffraction (RHEED), x-ray diffraction (XRD), photoluminescence (PL), and Van der Pauw–Hall effect measurements were performed to investigate the structural, optical, and electrical properties of the GaN epitaxial films grown on porous Si(100) by plasma-assisted molecular-beam epitaxy with a two-step method. The RHEED patterns were streaky with clear Kikuchi lines, which was direct evidence for layer-by-layer two-dimensional growth of GaN epitaxial layers on porous Si layers. The XRD curves showed that the grown layers were GaN(0001) epitaxial films. The results of the XRD and the PL measurements showed that the crystallinities of the GaN epilayers grown on porous Si by using a two-step growth were remarkably improved because the porous Si layer reduced the strains in the GaN epilayers by sharing them with the Si substrates. Hall-effect measurements showed that the mobility of the GaN active layer was higher than that of the GaN initial layer. These results indicate that high-quality GaN epitaxial films grown on porous Si(100) by using two-step growth hold promise for potential applications in new kinds of optoelectronic monolithic and ultralarge integrated circuits.

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Yang, Yibin, Lingxia Zhang e Yu Zhao. "Light Output Enhancement of GaN-Based Light-Emitting Diodes Based on AlN/GaN Distributed Bragg Reflectors Grown on Si (111) Substrates". Crystals 10, n. 9 (1 settembre 2020): 772. http://dx.doi.org/10.3390/cryst10090772.

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Due to the absorption of opaque Si substrates, the luminous efficiency of GaN-based light-emitting diodes (LEDs) on Si substrates is not high. So, in this work, we insert AlN/GaN distributed Bragg reflectors (DBRs) to improve the light output of GaN-based LEDs on Si (111) substrates grown via metal organic chemical vapor deposition (MOCVD). In order to obtain the highest reflectivity of the AlN/GaN DBR stop band, the growth parameters of AlN/GaN DBRs are optimized, including the growth temperature, the V/III ratio and the growth pressure. As a consequence, the interfaces of the optimal 9-pair AlN/GaN DBRs become abrupt, and the reflectivity of the DBR stop band is as high as 85.2%, near to the calculated value (92.5%). Finally, crack-free GaN-based LEDs with 5-pair AlN/GaN DBRs are grown on Si (111) substrates. The light output of the DBR-based LED is evidently enhanced by 41.8% at the injection current of 350 mA, compared with the conventional DBR-based LED without DBRs. These results pave the way for the luminous efficiency improvement of future green and red GaN-based LEDs grown on Si substrates.

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Feng, Zhe Chuan, Jiamin Liu, Deng Xie, Manika Tun Nafisa, Chuanwei Zhang, Lingyu Wan, Beibei Jiang et al. "Optical, Structural, and Synchrotron X-ray Absorption Studies for GaN Thin Films Grown on Si by Molecular Beam Epitaxy". Materials 17, n. 12 (14 giugno 2024): 2921. http://dx.doi.org/10.3390/ma17122921.

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GaN on Si plays an important role in the integration and promotion of GaN-based wide-gap materials with Si-based integrated circuits (IC) technology. A series of GaN film materials were grown on Si (111) substrate using a unique plasma assistant molecular beam epitaxy (PA-MBE) technology and investigated using multiple characterization techniques of Nomarski microscopy (NM), high-resolution X-ray diffraction (HR-XRD), variable angular spectroscopic ellipsometry (VASE), Raman scattering, photoluminescence (PL), and synchrotron radiation (SR) near-edge X-ray absorption fine structure (NEXAFS) spectroscopy. NM confirmed crack-free wurtzite (w-) GaN thin films in a large range of 180–1500 nm. XRD identified the w- single crystalline structure for these GaN films with the orientation along the c-axis in the normal growth direction. An optimized 700 °C growth temperature, plus other corresponding parameters, was obtained for the PA-MBE growth of GaN on Si, exhibiting strong PL emission, narrow/strong Raman phonon modes, XRD w-GaN peaks, and high crystalline perfection. VASE studies identified this set of MBE-grown GaN/Si as having very low Urbach energy of about 18 meV. UV (325 nm)-excited Raman spectra of GaN/Si samples exhibited the GaN E2(low) and E2(high) phonon modes clearly without Raman features from the Si substrate, overcoming the difficulties from visible (532 nm) Raman measurements with strong Si Raman features overwhelming the GaN signals. The combined UV excitation Raman–PL spectra revealed multiple LO phonons spread over the GaN fundamental band edge emission PL band due to the outgoing resonance effect. Calculation of the UV Raman spectra determined the carrier concentrations with excellent values. Angular-dependent NEXAFS on Ga K-edge revealed the significant anisotropy of the conduction band of w-GaN and identified the NEXAFS resonances corresponding to different final states in the hexagonal GaN films on Si. Comparative GaN material properties are investigated in depth.

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Lendyashova, V. V., K. P. Kotlyar, V. O. Gridchin, R. R. Reznik, A. I. Lihachev, I. P. Soshnikov e G. E. Cirlin. "Effect of wet KOH etching on structural properties of GaN nanowires grown on patterned SiOx/Si substrates". Journal of Physics: Conference Series 2103, n. 1 (1 novembre 2021): 012098. http://dx.doi.org/10.1088/1742-6596/2103/1/012098.

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Abstract The possibility of the controlled removal of GaN nanowires (NWs) from an SiOx inhibitor layer of patterned SiOx/Si substrates has been demonstrated. It has been found that the wet KOH etching preserves the selectively grown GaN NWs on Si surface, whereas the GaN NWs grown on inhibitor SiOx layer are removing. The effect is described by the difference in polarity between GaN NWs grown on a Si surface and NWs grown on a SiOx inhibitor layer.

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Yang, Xin, Baoxing Duan e Yintang Yang. "GaN/Si Heterojunction VDMOS with High Breakdown Voltage and Low Specific On-Resistance". Micromachines 14, n. 6 (31 maggio 2023): 1166. http://dx.doi.org/10.3390/mi14061166.

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A novel VDMOS with the GaN/Si heterojunction (GaN/Si VDMOS) is proposed in this letter to optimize the breakdown voltage (BV) and the specific on-resistance (Ron,sp) by Breakdown Point Transfer (BPT), which transfers the breakdown point from the high-electric-field region to the low-electric-field region and improves the BV compared with conventional Si VDMOS. The results of the TCAD simulation show that the optimized BV of the proposed GaN/Si VDMOS increases from 374 V to 2029 V compared with the conventional Si VDMOS with the same drift region length of 20 μm, and the Ron,sp of 17.2 mΩ·cm2 is lower than 36.5 mΩ·cm2 for the conventional Si VDMOS. Due to the introduction of the GaN/Si heterojunction, the breakdown point is transferred by BPT from the higher-electric-field region with the largest radius of curvature to the low-electric-field region. The interfacial state effects of the GaN/Si are analyzed to guide the fabrication of the GaN/Si heterojunction MOSFETs.

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Dvoretckaia, Liliia, Vladislav Gridchin, Alexey Mozharov, Alina Maksimova, Anna Dragunova, Ivan Melnichenko, Dmitry Mitin, Alexandr Vinogradov, Ivan Mukhin e Georgy Cirlin. "Light-Emitting Diodes Based on InGaN/GaN Nanowires on Microsphere-Lithography-Patterned Si Substrates". Nanomaterials 12, n. 12 (10 giugno 2022): 1993. http://dx.doi.org/10.3390/nano12121993.

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The direct integration of epitaxial III-V and III-N heterostructures on Si substrates is a promising platform for the development of optoelectronic devices. Nanowires, due to their unique geometry, allow for the direct synthesis of semiconductor light-emitting diodes (LED) on crystalline lattice-mismatched Si wafers. Here, we present molecular beam epitaxy of regular arrays n-GaN/i-InGaN/p-GaN heterostructured nanowires and tripods on Si/SiO2 substrates prepatterned with the use of cost-effective and rapid microsphere optical lithography. This approach provides the selective-area synthesis of the ordered nanowire arrays on large-area Si substrates. We experimentally show that the n-GaN NWs/n-Si interface demonstrates rectifying behavior and the fabricated n-GaN/i-InGaN/p-GaN NWs-based LEDs have electroluminescence in the broad spectral range, with a maximum near 500 nm, which can be employed for multicolor or white light screen development.

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Emori, Kenta, Toshiharu Marui, Yuji Saito, Wei Ni, Yasushi Nakajima, Tetsuya Hayashi e Masakatsu Hoshi. "Novel Poly-Si/GaN Vertical Heterojunction Diode". Materials Science Forum 821-823 (giugno 2015): 1015–18. http://dx.doi.org/10.4028/www.scientific.net/msf.821-823.1015.

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We previously reported a unipolar mode p+-polycrystalline silicon (poly-Si)/4H-SiC heterojunction diode (SiC-HJD) [1-3]. In this work, we demonstrate a poly-Si/GaN vertical unipolar heterojunction diode (GaN-HJD) based on numerical simulation and experimental results. The GaN-HJD is expected to control the electrical characteristics of both Schottky action with a p-type poly-Si and ohmic action with an n-type poly-Si. We investigated the detailed physics of the GaN-HJD between p+Si and n+Si by numerical simulation. The GaN-HJD was also fabricated with p+-type polycrystalline silicon on an n--type epitaxial layer on bulk GaN substrates. The measured barrier height of the GaN-HJD was 0.79 eV and the ideality factor was 1.10.

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Wu, Nengtao, Zhiheng Xing, Shanjie Li, Ling Luo, Fanyi Zeng e Guoqiang Li. "GaN-based power high-electron-mobility transistors on Si substrates: from materials to devices". Semiconductor Science and Technology 38, n. 6 (25 aprile 2023): 063002. http://dx.doi.org/10.1088/1361-6641/acca9d.

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Abstract Conventional silicon (Si)-based power devices face physical limitations—such as switching speed and energy efficiency—which can make it difficult to meet the increasing demand for high-power, low-loss, and fast-switching-frequency power devices in power electronic converter systems. Gallium nitride (GaN) is an excellent candidate for next-generation power devices, capable of improving the conversion efficiency of power systems owing to its wide band gap, high mobility, and high electric breakdown field. Apart from their cost effectiveness, GaN-based power high-electron-mobility transistors (HEMTs) on Si substrates exhibit excellent properties—such as low ON-resistance and fast switching—and are used primarily in power electronic applications in the fields of consumer electronics, new energy vehicles, and rail transit, amongst others. During the past decade, GaN-on-Si power HEMTs have made major breakthroughs in the development of GaN-based materials and device fabrication. However, the fabrication of GaN-based HEMTs on Si substrates faces various problems—for example, large lattice and thermal mismatches, as well as ‘melt-back etching’ at high temperatures between GaN and Si, and buffer/surface trapping induced leakage current and current collapse. These problems can lead to difficulties in both material growth and device fabrication. In this review, we focused on the current status and progress of GaN-on-Si power HEMTs in terms of both materials and devices. For the materials, we discuss the epitaxial growth of both a complete multilayer HEMT structure, and each functional layer of a HEMT structure on a Si substrate. For the devices, breakthroughs in critical fabrication technology and the related performances of GaN-based power HEMTs are discussed, and the latest development in GaN-based HEMTs are summarised. Based on recent progress, we speculate on the prospects for further development of GaN-based power HEMTs on Si. This review provides a comprehensive understanding of GaN-based HEMTs on Si, aiming to highlight its development in the fields of microelectronics and integrated circuit technology.

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Islam, Mirwazul, e Grigory Simin. "Bulk Current Model for GaN-on-Si High Electron Mobility Transistors". International Journal of High Speed Electronics and Systems 25, n. 01n02 (marzo 2016): 1640002. http://dx.doi.org/10.1142/s0129156416400024.

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Drain to substrate current is an important parameter affecting loss, breakdown and reliability of power GaN HEMTs on Si substrates; however, no clear model of the current has been established. This work proposes a novel approach describing the drain to substrate current as a function of equivalent Si/GaN interface barrier. The modeling results are in close agreement with experimental observations; they reveal an important role of space charge injection from Si substrate into GaN buffer. Compact model closely reproducing experimental data is presented. The results are important for GaN on Si power switches development.

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Visalli, D., J. Derluyn, B. Sijmus, S. Degroote e M. Germain. "GaN-on-Si for Power Technology". ECS Transactions 50, n. 3 (15 marzo 2013): 173–76. http://dx.doi.org/10.1149/05003.0173ecst.

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Krost, A. "Controlling stress in GaN-on-Si". Acta Crystallographica Section A Foundations of Crystallography 67, a1 (22 agosto 2011): C73. http://dx.doi.org/10.1107/s0108767311098229.

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Середин, П. В., Д. Л. Голощапов, Д. С. Золотухин, А. С. Леньшин, А. М. Мизеров, И. Н. Арсентьев, Harald Leiste e Monika Rinke. "Структурные и морфологичеcкие свойства гибридных гетероструктур на основе GaN, выращенного на "податливой" подложке por-Si(111)". Физика и техника полупроводников 53, n. 8 (2019): 1141. http://dx.doi.org/10.21883/ftp.2019.08.48009.9083.

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AbstractThe possibility of synthesizing integrated GaN/por-Si heterostructures by plasma-assisted molecular beam epitaxy without an A1N/Si buffer layer is demonstrated. The beneficial effect of the high-temperature nitridation of a silicon substrate before GaN growth on the crystal quality of the GaN/Si layers is shown. It is established that, to obtain two-dimensional GaN layers on Si(111), it is reasonable to use compliant por-Si substrates and low-temperature GaN seed layers with a 3D morphology synthesized by plasma-assisted molecular beam epitaxy at relatively low substrate temperatures under stoichiometric conditions and upon enrichment with nitrogen. In this case, a self-assembled array of GaN seed nanocolumns with a fairly uniform diameter distribution forms on the por-Si substrate surface. The basic GaN layers, in turn, should be grown at a high temperature under stoichiometric conditions upon enrichment with gallium, upon which the coalescence of nucleated GaN nanocolumns and growth of a continuous two-dimensional GaN layer are observed. The use of compliant Si substrates is a relevant approach for forming GaN-based semiconductor device heterostructures by plasma-assisted molecular beam epitaxy.

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Pharkphoumy, Sakhone, Vallivedu Janardhanam, Tae-Hoon Jang, Kyu-Hwan Shim e Chel-Jong Choi. "Correlation of Crystal Defects with Device Performance of AlGaN/GaN High-Electron-Mobility Transistors Fabricated on Silicon and Sapphire Substrates". Electronics 12, n. 4 (20 febbraio 2023): 1049. http://dx.doi.org/10.3390/electronics12041049.

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Herein, the performance of AlGaN/GaN high-electron-mobility transistor (HEMT) devices fabricated on Si and sapphire substrates is investigated. The drain current of the AlGaN/GaN HEMT fabricated on sapphire and Si substrates improved from 155 and 150 mA/mm to 290 and 232 mA/mm, respectively, at VGS = 0 V after SiO2 passivation. This could be owing to the improvement in the two-dimensional electron gas charge and reduction in electron injection into the surface traps. The SiO2 passivation resulted in the augmentation of breakdown voltage from 245 and 415 V to 400 and 425 V for the AlGaN/GaN HEMTs fabricated on Si and sapphire substrates, respectively, implying the effectiveness of SiO2 passivation. The lower transconductance of the AlGaN/GaN HEMT fabricated on the Si substrate can be ascribed to the higher self-heating effect in Si. The X-ray rocking curve measurements demonstrated that the AlGaN/GaN heterostructures grown on sapphire exhibited a full-width half maximum of 368 arcsec against 703 arcsec for the one grown on Si substrate, implying a better crystalline quality of the AlGaN/GaN heterostructure grown on sapphire. The AlGaN/GaN HEMT fabricated on the sapphire substrate exhibited better performance characteristics than that on the Si substrate, owing to the high crystalline quality and improved surface.

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Kim, Shin Young, e Ho-Young Cha. "Study on Self-Heating Effects in AlGaN/GaN-on-Si Power Transistors". Journal of the Institute of Electronics Engineers of Korea 50, n. 2 (25 febbraio 2013): 91–97. http://dx.doi.org/10.5573/ieek.2013.50.2.091.

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Hiroyama, Yuichi, e Masao Tamura. "Cubic GaN Heteroepitaxy on Thin-SiC-Covered Si(001)". MRS Internet Journal of Nitride Semiconductor Research 4, S1 (1999): 155–60. http://dx.doi.org/10.1557/s1092578300002386.

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We have investigated the growth conditions of cubic GaN (β-GaN) layers on very thin SiC-covered Si(001) by using gas-source molecular beam epitaxy as functions of SiC layer thickness, Ga-cell temperature and substrate temperature. Under the present SiC formation conditions on Si substrates by carbonization using C2H2 gas, the SiC layers with the thickness between 2.5 and 4 nm result in the epitaxial growth of β-GaN on thus SiC-formed Si substrates. At the highest GaN growth rate of 110 nm/h ( a Ga-cell temperature of 950 °C), β-GaN layers grown at a substrate temperature of 700 °C show a nearly flat surface morphology and the fraction of included hexagonal GaN becomes negligible when compared to the results of β-GaN layers grown under other conditions of Ga-cell and substrate temperatures. Thus obtained β-GaN films have good performance in photoluminescence intensity although the FWHM of band-edge recombination peak is still wider (137 meV) than the reported values for the β-GaN on 3C-SiC and GaAs.

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Середин, П. В., Д. Л. Голощапов, Д. С. Золотухин, А. С. Леньшин, А. М. Мизеров, С. Н. Тимошнев, Е. В. Никитина, И. Н. Арсентьев e С. А. Кукушкин. "Оптические свойства гибридных гетероструктур GaN/SiC/por-Si/Si(111)". Физика и техника полупроводников 54, n. 4 (2020): 346. http://dx.doi.org/10.21883/ftp.2020.04.49138.9323.

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Abstract Using a complex of structural and spectroscopic methods of diagnostics, the influence of a nanoporous-silicon ( por -Si) transition layer on the optical properties of GaN layers grown on SiC/ por -Si/ c -Si templates by molecular-beam epitaxy with the plasma activation (MBE PA) of nitrogen is studied. It is shown for the first time that the MBE PA technology of the synthesis of GaN on a virtual SiC/ por -Si/ c -Si substrate provides a means for producing a GaN film of much higher structural and optical quality at a much lower growth temperature compared to those in similar studies, in which growth on porous Si substrates is demonstrated. The use of a por -Si layer makes it possible to improve the structural and morphological properties of the GaN epitaxial layer and to attain unique optical and electrical characteristics of the layer. The data obtained in the study will serve as an important basis for understanding the foundations of the physics of GaN/SiC/ por -Si nanoheterostructures and for promoting their potential use in optoelectronics.

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27

Timoshnev, Sergei, Andrey Mizerov, Maxim Sobolev e Ekaterina Nikitina. "Growth of GaN layers on Si(111) substrates by plasma-assisted molecular beam epitaxy". Физика и техника полупроводников 52, n. 5 (2018): 524. http://dx.doi.org/10.21883/ftp.2018.05.45868.57.

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AbstractThe studies of the growth kinetics of GaN layers grown on nitridated Si(111) substrates by plasmaassisted molecular beam epitaxy are presented. The nucleation and overgrowth of the separate GaN/Si(111) nanocolumns during single growth run is demonstrated. The technique of the in situ control of the GaN/Si(111) nanocolumns lateral size is proposed.

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28

Naeemul Islam, Mohamed Fauzi Packeer Mohamed, Siti Fatimah Abd Rahman, Mohd Syamsul, Hiroshi Kawarada e Alhan Farhanah Abd Rahim. "Enhanced Breakdown Voltage of AlGaN/GaN MISHEMT using GaN Buffer with Carbon-Doping on Silicon for Power Device". International Journal of Nanoelectronics and Materials (IJNeaM) 17, n. 2 (19 aprile 2024): 204–10. http://dx.doi.org/10.58915/ijneam.v17i2.684.

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In recent years, Gallium Nitride (GaN)-based metal-insulator-semiconductor high-electron-mobility transistors (MISHEMTs) have attracted interest in high-power and high-frequency applications. The breakdown mechanism in E-mode GaN MISHEMTs with carbon doping in the GaN buffer grown on a Silicon (Si) substrate (Sub) was investigated using technology computer-aided design simulations. Results showed that GaN MISHEMTs without Si Sub had a breakdown voltage (BV) of 600 V. However, after adding Si Sub to the GaN buffer layer, the electric field (EF) increased, creating a vertical breakdown through the total buffer thickness, therefore, BV was reduced to around 240 V. On the other hand, BV is increased to approximately >1100 V, and the Electric field is reduced after employing a carbon deep acceptor with the proper doping concentration in this device. The GaN MISHEMTs with Si Sub is presented as threshold voltage +1.5 V with transconductance of 700 mS/mm, which is an excellent result compared to GaN MISHEMTs without Si Sub. Eventually, the study device depicted higher BV performance compared to other C-doped GaN HEMT devices. This suggests that the designed GaN MISHEMTs device could effectively be used in power semiconductor devices with optimum performance.

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29

Zhou, Yan, Shi Zhou, Shun Wan, Bo Zou, Yuxia Feng, Rui Mei, Heng Wu et al. "Tuning the interlayer microstructure and residual stress of buffer-free direct bonding GaN/Si heterostructures". Applied Physics Letters 122, n. 8 (20 febbraio 2023): 082103. http://dx.doi.org/10.1063/5.0135138.

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The direct integration of GaN with Si can boost great potential for low-cost, large-scale, and high-power device applications. However, it is still challengeable to directly grow GaN on Si without using thick strain relief buffer layers due to their large lattice and thermal-expansion-coefficient mismatches. In this work, a GaN/Si heterointerface without any buffer layer is fabricated at room temperature via surface activated bonding (SAB). The residual stress states and interfacial microstructures of GaN/Si heterostructures were systematically investigated through micro-Raman spectroscopy and transmission electron microscopy. Compared to the large compressive stress that existed in GaN layers grown on Si by metalorganic chemical vapor deposition, a significantly relaxed and uniform small tensile stress was observed in GaN layers bonded to Si by SAB; this is mainly ascribed to the amorphous layer formed at the bonding interface. In addition, the interfacial microstructure and stress states of bonded GaN/Si heterointerfaces was found to be significantly tuned by appropriate thermal annealing. With increasing annealing temperature, the amorphous interlayer formed at the as-bonded interface gradually transforms into a thin crystallized interlayer without any observable defects even after annealing at 1000 °C, while the interlayer stresses at both GaN layer and Si monotonically change due to the interfacial re-crystallization. This work moves an important step forward directly integrating GaN to the present Si CMOS technology with high quality thin interfaces and brings great promises for wafer-scale low-cost fabrication of GaN electronics.

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30

Yang, Shu, Qimeng Jiang, Baikui Li, Zhikai Tang e Kevin J. Chen. "GaN-to-Si vertical conduction mechanisms in AlGaN/GaN-on-Si lateral heterojunction FET structures". physica status solidi (c) 11, n. 3-4 (febbraio 2014): 949–52. http://dx.doi.org/10.1002/pssc.201300439.

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31

Bazin, Anne Elisabeth, Frédéric Cayrel, Mohamed Lamhamdi, Arnaud Yvon, Jean Christophe Houdbert, Emmanuel Collard e Daniel Alquier. "Si⁺ Implantation and Activation in GaN Comparison of GaN on Sapphire and GaN on Silicon". Materials Science Forum 711 (gennaio 2012): 213–17. http://dx.doi.org/10.4028/www.scientific.net/msf.711.213.

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In this paper, we evaluated gallium nitride heteroepitaxially grown on sapphire (GaN/Sa) and grown on silicon (GaN/Si) faced to implantation doping. Si+ was implanted on low doped n-type epilayers in order to create a plateau around 1020at.cm-3. All the samples were capped with a silicon oxide and annealed between 1000°C and 1150°C. The surface quality was evaluated in terms of roughness, pit density and maximum pit diameter using Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM). Finally, the dopant electrical activation was studied with Ti-Al contacts using the circular Transfert Length Method (c-TLM). This study shows that low Specific Contact Resistance (SCR) values of 8x10-5Ω.cm2 and 6x10-6Ω.cm2 are respectively obtained on GaN/Sa sample annealed at 1150°C-2min and on GaN/Si sample annealed at 1150°C-30s, proving that good ohmic contacts are obtained on both materials. Nevertheless, a compromise has to be done between the low SCR values obtained and the GaN surface degradation, observed by AFM and SEM after the different annealing treatments and which could affect the good behaviour of the GaN devices.

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32

Roshko, Alexana, Matt Brubaker, Paul Blanchard, Todd Harvey e Kris Bertness. "Selective Area Growth and Structural Characterization of GaN Nanostructures on Si(111) Substrates". Crystals 8, n. 9 (16 settembre 2018): 366. http://dx.doi.org/10.3390/cryst8090366.

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Selective area growth (SAG) of GaN nanowires and nanowalls on Si(111) substrates with AlN and GaN buffer layers grown by plasma-assisted molecular beam epitaxy was studied. For N-polar samples filling of SAG features increased with decreasing lattice mismatch between the SAG and buffer. Defects related to Al–Si eutectic formation were observed in all samples, irrespective of lattice mismatch and buffer layer polarity. Eutectic related defects in the Si surface caused voids in N-polar samples, but not in metal-polar samples. Likewise, inversion domains were present in N-polar, but not metal-polar samples. The morphology of Ga-polar GaN SAG on nitride buffered Si(111) was similar to that of homoepitaxial GaN SAG.

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33

Yang, S. J., T. W. Kang, T. W. Kim e K. S. Chung. "Dependence of the Au/Ni/Si/Ni Contact Properties on the Si-layer Thickness and the Annealing Temperature in p-type GaN Epilayers". Journal of Materials Research 17, n. 5 (maggio 2002): 1019–23. http://dx.doi.org/10.1557/jmr.2002.0150.

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The dependences of the properties of Au/Ni/Si/Ni contacts, deposited on p-GaN epilayers by using electron-beam evaporation, on the Si layer thickness and the annealing temperature were investigated with the goal of producing contacts with low specific resistances. The results of the current–voltage (I–V) curves showed that the lowest specific contact resistance obtained for the Au/Ni/Si/Ni contact with a 1200-Å- thick Si layer on p-type GaN annealed at 700 °C for 1 min in a nitrogen atmosphere was 8.49 × 10-4 Ω cm2. The x-ray diffraction (XRD) measurements on the annealed Au/Ni/Si/Ni/p-GaN/sapphire heterostructure showed that Ni3Si, GaAu, and NiGa layers were formed at the Au/Ni/Si/Ni/p-GaN interfaces. While the intensities corresponding to the Ni3Si layer decreased with increasing annealing temperature above 700 °C, those related to the GaAu and the NiGa layers increased with increasing temperature. These results indicate that the Au/Ni/Si/Ni contacts with 1200-Å-thick Si layers annealed at 700 °C hold promise for potential applications in p-GaN-based optoelectronic devices.

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34

Kim, Zin-Sig, Hyung-Seok Lee, Sung-Bum Bae, Hokyun Ahn, Sang-Heung Lee, Jong-Won Lim e Dong Min Kang. "Thermal Behavior of an AlGaN/GaN-Based Schottky Barrier Diode on Diamond and Silicon Substrates". Journal of Nanoscience and Nanotechnology 21, n. 8 (1 agosto 2021): 4429–33. http://dx.doi.org/10.1166/jnn.2021.19421.

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Abstract (sommario):

Devices based on AlGaN/GaN heterostructures, for example, Schottky barrier diodes (SBDs) and high electron mobility transistors (HEMTs), have been intensively investigated for applications to high-frequency and high-power areas. Presently, the substrates widely distributed are AlGaN/GaN on SiC for its high performance in radio frequency (RF) applications, for examples high cutoff frequency (fT) or high maximum oscillation frequency (fmax), and AlGaN/GaN on Si for its high power performance, for examples high breakdown voltage or high voltage operation. Chemical vapor deposition (CVD) diamond substrates have a thermal conductivity of 12 W/cm·K, and this is a remarkable point because HEMTs or SBDs on AlGaN/GaN on CVD diamonds are one of the promising alternatives for power and RF applications. In comparison, the thermal conductivity of AlGaN/GaN on a sapphire substrate is 0.33 W/cm·K while that of AlGaN/GaN on a Si substrate is 1.3 W/cm·K and that of AlGaN/GaN on a SiC substrate is 4.9 W/cm·K. In this work, we fabricated SBDs with a 137 mm Schottky channel length on AlGaN/GaN on Si and also on a CVD diamond substrate. We also compared the thermal behaviors of these fabricated large scale SBDs on Si and a CVD diamond substrate.

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35

Huang, Chong-Rong, Hsien-Chin Chiu, Chia-Hao Liu, Hsiang-Chun Wang, Hsuan-Ling Kao, Chih-Tien Chen e Kuo-Jen Chang. "Characteristic Analysis of AlGaN/GaN HEMT with Composited Buffer Layer on High-Heat Dissipation Poly-AlN Substrates". Membranes 11, n. 11 (30 ottobre 2021): 848. http://dx.doi.org/10.3390/membranes11110848.

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In this study, an AlGaN/GaN high-electron-mobility transistor (HEMT) was grown through metal organic chemical vapor deposition on a Qromis Substrate Technology (QST). The GaN on the QST device exhibited a superior heat dissipation performance to the GaN on a Si device because of the higher thermal conductivity of the QST substrate. Thermal imaging analysis indicated that the temperature variation of the GaN on the QST device was 4.5 °C and that of the GaN on the Si device was 9.2 °C at a drain-to-source current (IDS) of 300 mA/mm following 50 s of operation. Compared with the GaN HEMT on the Si device, the GaN on the QST device exhibited a lower IDS degradation at high temperatures (17.5% at 400 K). The QST substrate is suitable for employment in different temperature environments because of its high thermal stability.

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36

Pantellini, Alessio, Claudio Lanzieri, Antonio Nanni, Andrea Bentini, Walter Ciccognani, Sergio Colangeli e Ernesto Limiti. "GaN-on-Silicon Evaluation for High-Power MMIC Applications". Materials Science Forum 711 (gennaio 2012): 223–27. http://dx.doi.org/10.4028/www.scientific.net/msf.711.223.

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Abstract (sommario):

Today microwave market has identified GaN-HEMT technology as a strategic enabling technology for next generation MMICs to be implemented in high performance RF sub-assemblies such as T/R Modules, Solid State Power Transmitters, Compact Receivers, High Speed Communications. To allow commercial market entry of GaN technology, a tradeoff between high RF performance and low cost is mandatory and a possible solution is represented by GaN-on-Silicon substrate. In this scenario the evaluation of FETs RF performance and losses of passive components are demanding to understand the feasibility of GaN MMIC on Si. Following such approach, in SELEX Sistemi Integrati a 4 inches GaN-on-Si wafer containing discrete active devices and passive components has been fabricated with the 50μm Si thickness. RF FETs performance demonstrates an output power of 4W/mm @ 3GHz, while passive components characterization exhibits similar behavior of GaN SiC passive elements up to C Band.

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37

Yu, Huiqiang, Lin Chen, Rong Zhang, Xiang Qian Xiu, Zi Li Xie, Yu Da Ye, Shu Lin Gu, Bo Shen, Yi Shi e You Dou Zheng. "The Growth of GaN Films on Si Substrates by HVPE". Materials Science Forum 475-479 (gennaio 2005): 3783–86. http://dx.doi.org/10.4028/www.scientific.net/msf.475-479.3783.

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GaN films are grown on Si(111) with low-temperature GaN (LT-GaN) layers as buffer layers by hydride vapor phase epitaxy (HVPE). The LT-GaN layers are deposited at different temperatures ranging from 400 to 900 °C. The surface property, the structure and optical properties of the GaN films with different LT-GaN layers are studied. When deposition temperature of LT-GaN layer is 600 °C, the GaN film shows the best properties.

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38

Selvaraj, S. Lawrence, e Takashi Egawa. "MOCVD Grown AlGaN/GaN Transistors on Si Substrate for High Power Device Applications". Materials Science Forum 711 (gennaio 2012): 195–202. http://dx.doi.org/10.4028/www.scientific.net/msf.711.195.

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An extensive study on the use of Si as a substrate for the growth of AlGaN/GaN layers for High-Electron-Mobility Transistor (HEMT) were studied and reported in this article. We have used thick buffers to grow high resistive i-GaN by MOCVD which offers a high breakdown voltage. While the leakage through buffer and substrate can be controlled by thick buffer, the leakage through gate is controlled using a thin 2-nm in-situ grown i-GaN cap layer. We have evidenced a high figure of merit (BV2/RON) of 2.6 x 108 V2Ω-1cm-2 for AlGaN/GaN HEMTs grown on 4-inch Si substrate. The challenges before the MOCVD growth of GaN on Si is also discussed in detail.

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39

Piner, E. L., D. M. Keogh, J. S. Flynn e J. M. Redwing. "AlGaN/GaN High Electron Mobility Transistor Structure Design and Effects on Electrical Properties". MRS Internet Journal of Nitride Semiconductor Research 5, S1 (2000): 349–54. http://dx.doi.org/10.1557/s109257830000449x.

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We report on the effect of strain induced polarization fields in AlGaN/GaN heterostructures due to the incorporation of Si dopant ions in the lattice. By Si-doping (Al)GaN, a contraction of the wurtzite unit cell can occur leading to strain in doped AlGaN/GaN heterostructures such as high electron mobility transistors (HEMTs). In a typical modulation doped AlGaN/GaN HEMT structure, the Si-doped AlGaN supply layer is separated from the two-dimensional electron gas channel by an undoped AlGaN spacer layer. This dopant-induced strain, which is tensile, can create an additional source of charge at the AlGaN:Si/AlGaN interface. The magnitude of this strain increases as the Si doping concentration increases and the AlN mole fraction in the AlGaN decreases. Consideration of this strain should be given in AlGaN/GaN HEMT structure design.

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40

Pham, Nga P., Maarten Rosmeulen, Cindy Demeulemeester, Vasyl Motsnyi, Deniz S. Tezcan e Haris Osman. "Substrate Transfer for GaN based LEDs grown on Silicon". International Symposium on Microelectronics 2011, n. 1 (1 gennaio 2011): 000130–35. http://dx.doi.org/10.4071/isom-2011-ta4-paper3.

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This paper focuses on the substrate transfer process which is applied after the fabrication of LEDs on 4 inch Si (111) wafers comprising p and n contact formation to the GaN layer. After applying a passivation layer, a bonding metal is deposited. The wafer is then bonded to a Si carrier substrate using metallic bonding. Next, the original Si (111) substrate is completely removed by grinding and wet etching. GaN-LEDs are thus transferred to a new carrier substrate. The last step is etching of the transferred GaN layer from the back to open the contacts. A surface roughening technique on the backside of the transferred GaN layer to improve the light extraction efficiency of GaN-LEDs is also investigated. All the issues of the substrate transfer process steps such as permanent Cu/Sn bonding, thinning by grinding and wet etching will be discussed in detailed. A typical issue occurring during processing of GaN-LEDs on Si substrates is high stress and related large wafer bow originating from the GaN layer and the thick Cu/Sn metal bonding layer. Such a large wafer bow causes problems for some automatic handling tools and processes like lithography. Solutions to manage the stress and wafer bow have been investigated.

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41

Bessolov, Vasily N., Elena V. Konenkova, Tatiana A. Orlova e Sergey N. Rodin. "Semi-polar GaN(11-22) on nano-structured Si(113): a structure for reducing thermal stresses". Kondensirovannye sredy i mezhfaznye granitsy = Condensed Matter and Interphases 25, n. 4 (12 ottobre 2023): 514–19. http://dx.doi.org/10.17308/kcmf.2023.25/11477.

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The article reports the growth of semi-polar GaN(11-22) layers using epitaxy from metal organic compounds on a nanostructured NP-Si(113) substrate. It was shown that upon the emergence of an island layer, elastic deformed structures of GaN(11-22)/NP-Si(113) form a nano-meter compliant silicon layer on a substrate while elastic stresses conditioned by the difference of temperature coefficients of GaN and Si in such a structure decrease

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42

Arifin, Pepen, Heri Sutanto, Sugianto e Agus Subagio. "Plasma-Assisted MOCVD Growth of Non-Polar GaN and AlGaN on Si(111) Substrates Utilizing GaN-AlN Buffer Layer". Coatings 12, n. 1 (14 gennaio 2022): 94. http://dx.doi.org/10.3390/coatings12010094.

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Abstract (sommario):

We report the growth of non-polar GaN and AlGaN films on Si(111) substrates by plasma-assisted metal-organic chemical vapor deposition (PA-MOCVD). Low-temperature growth of GaN or AlN was used as a buffer layer to overcome the lattice mismatch and thermal expansion coefficient between GaN and Si(111) and GaN’s poor wetting on Si(111). As grown, the buffer layer is amorphous, and it crystalizes during annealing to the growth temperature and then serves as a template for the growth of GaN or AlGaN. We used scanning electron microscopy (SEM), atomic force microscopy (AFM), and X-ray diffraction (XRD) characterization to investigate the influence of the buffer layer on crystal structure, orientation, and the morphology of GaN. We found that the GaN buffer layer is superior to the AlN buffer layer. The thickness of the GaN buffer layer played a critical role in the crystal quality and plane orientation and in reducing the cracks during the growth of GaN/Si(111) layers. The optimum GaN buffer layer thickness is around 50 nm, and by using the optimized GaN buffer layer, we investigated the growth of AlGaN with varying Al compositions. The morphology of the AlGaN films is flat and homogenous, with less than 1 nm surface roughness, and has preferred orientation in a-axis.

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Han, Ji Sheng, Sima Dimitrjiev, Li Wang, Alan Iacopi, Qu Shuang e Xian Gang Xu. "InGaN/GaN Multiple Quantum Well Blue LEDs on 3C-SiC/Si Substrate". Materials Science Forum 679-680 (marzo 2011): 801–3. http://dx.doi.org/10.4028/www.scientific.net/msf.679-680.801.

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Abstract (sommario):

Gallium nitrides are primarily used for their excellent light emission properties. GaN LEDs are mostly grown on foreign substrates, essentially sapphire and SiC, but more recently, also on Si substrates. In this paper, we will demonstrate that the high structural quality of InGaN/GaN multiple quantum wells can be deposited on 3C-SiC/Si (111) substrate using MOCVD. This demonstrates that 3C-SiC/Si is a promising template for the epitaxial growth of InGaN/GaN multiple quantum wells for LEDs.

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Yun, SeongUk, Andrew C. Kummel e Kesong Wang. "Controlled Surface Polarity and Crystallinity of Gallium Nitride on Si (111) Using Atomic Layer Deposition for Selective Wet-Etch and STEM Analysis". ECS Meeting Abstracts MA2024-02, n. 36 (22 novembre 2024): 2528. https://doi.org/10.1149/ma2024-02362528mtgabs.

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Gallium nitride (GaN) has gained interest as photoelectronic materials and a buffer layer for other III-V deposition with applications in power electronics operated at high voltage and high temperature. The crystallinity and polarity of III-V semiconductors have a key role for the passivation layers on microLED, the formation of 2D electron gasses in high electron mobility transistors, and for templating growth of piezoelectric materials. The atomic layer annealing (ALA) was reported to improve the crystallinity of the III-V compounds (aluminum nitride) at low temperatures as compared to the conventional thermal ALD. In ALA, a pulse of ion bombardment is added to each ALD cycle to ensure polycrystalline film formation at low temperature. Polycrystalline GaN has been deposited by ALA at low temperatures even on amorphous substrates, but the polarity was not reported. The selective wet-etch process has several advantages for the III-V semiconductor device integration since the conventional plasma ion etching process is expensive, complicated, and leads to the surface damage by reactive plasma ion. The GaN surface polarity (N-polar or metal-polar) on sapphire was selectively etched by aqueous KOH solution. However, electrochemical etching study on the polarity of GaN ALD films has not yet been studied as types of ALD process. Figure 1a and 1b show the process parameter switching diagram for the GaN thermal ALD and GaN ALA processes, respectively. The chemical compositions of ALA and ALD GaN on Si were estimated by in-situ AES as shown in Figure 1c. Lower O content (below 3.3 at. %) and higher N/Ga atomic ratio were observed in the ALA GaN on Si (111) as compared to the thermal ALD GaN film (4.6 at. %). Figure 1d shows that the intensity of GaN (002) XRD pattern in thermal ALD GaN on Si was greatly improved in the GaN stacks (GaN thermal ALD/ALA/Si) with an ALA GaN buffer layer. The electrochemical behavior of the GaN ALD films was studied to elucidate the impact of surface polarity on selective KOH wet-etch. The linear sweep voltammograms of GaN thermal ALD and GaN ALA films in 1 M KOH solution were shown in Figure 1e. The applied potential was swept from zero (vs. Normal Hydrogen Electrode) to positive 3.7 V. The peak of current density at ~1.7 V was observed in the voltammogram of the GaN ALA film (N-polar), suggesting the occurrence of etching reaction by the dissolution and formation via the equations in Figure 1f. On the other hand, the absence of current density peak in the GaN thermal ALD film (Ga-polar) could suggest the unfavorable etching reaction as compared to the GaN ALA film. Figure 2a and 2b shows the HAADF-STEM images of ALD GaN on Si demonstrate highly ordered 3 nm x 5 nm ALD GaN layers with bright and dark regions. The circles of bright regions and the center of dark regions represent Ga atoms and tunnel points (empty element), respectively. The GaN polarity could be determined by drawing triangles connecting adjacent three tunnel points without the interruption of Ga. Using this method, upward triangles were obtained in the HAADF-STEM image (Figure 2a), suggesting the formation of N-polar GaN layers during the ALA GaN process on Si. Conversely, downward triangles from the STEM image of thermal ALD GaN /ALA GaN /Si (Figure 2b) suggested Ga-polar GaN during GaN thermal ALD process. The inset figures show the top-view SEM image of selectively wet-etched (30 min, 20 wt.% KOH (aq)) GaN films. The etched surface on the ALA GaN layers (inset of Figure 2a) indicated N-polar GaN surface. The inset SEM image in Figure 2b shows a nearly unchanged GaN surface in thermal ALD GaN /ALA GaN / Si is consistent with the Ga-polar GaN surface. These observations are in good agreement with the HAADF-STEM images. The data is consistent with being able to control the polarity of GaN by switching between thermal ALD and ALA. The ion bombardment in ALA promotes N-polar GaN while thermal ALD promotes metal polar GaN. This allows the facile formation of both electron and hole gas layers between ALA and ALD GaN. Figure 1

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45

YE, ZHIZHEN, XING GU, JINGYUN HUANG, YU WANG, QINGHUI SHAO e BINGHUI ZHAO. "AN ULTRAVIOLET PHOTODETECTOR BASED ON GaN/Si". International Journal of Modern Physics B 16, n. 28n29 (20 novembre 2002): 4310–13. http://dx.doi.org/10.1142/s0217979202015327.

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Abstract (sommario):

Single crystalline GaN is grown on Si(111) by a vacuum reactive evaporation method. X-ray diffraction(XRD), scanning electron microscopy(SEM), photoluminescence measurement (PL), and Hall measurement results indicate that single crystalline wurtzite GaN film is grown on the microcrystalline GaN buffer layer on Si(111) substrate. The photoconductive ultraviolet photodetector with a metal-semiconductor-metal(MSM) structure is prepared on the unintentionally doped n-type GaN film and the properties of the detector are investigated. The detector has a peak photocurrent responsivity at 365nm and a abrupt cut-off curve. The responsivity increased with the increasing of bias voltage. The responsivity saturated when the bias voltage reached 7V. The response time was ms level under normal conditions and dropped with the increase of bias voltage before the bias voltage reached its saturation.

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Mao, Zhigang, Stuart McKernan, C. Barry Carte, Wei Yang e Scott A. McPherson. "Horizontal Defects Parallel to the Interface in GaN Pyramids". Microscopy and Microanalysis 5, S2 (agosto 1999): 734–35. http://dx.doi.org/10.1017/s1431927600016998.

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Abstract (sommario):

The performance of III-V nitride-based microelectronic and optoelectronic devices relates directly to the micro structure of these materials. Selective lateral overgrowth has been exploited to produce GaN heteroepitaxial films with low defect density [1]. Si is a promising substrate due to its low cost, large size, and the potential for the intergration of GaN-based optoelectronic devices with Si-based electronics. It is also possible to produce high-quality GaN material for devices using lateral overgrowth on a Si substrate [2]. At present, only limited information on the defect structure in GaN heteroepitaxial films grown by selective lateral growth is available, especially those grown on Si substrate. Recent work [3] on GaN pyramids grown on (111) Si substrates by this method has shown that in the center, or core, of the GaN pyramid (at and above the window area) dislocations thread through the pyramid nearly perpendicular to the substrate surface and the dislocation density is quite high.

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47

Reznik, Rodion R., Vladislav O. Gridchin, Konstantin P. Kotlyar, Vladimir V. Neploh, Andrei V. Osipov, Sergey A. Kukushkin, Omar Saket, Maria Tchernycheva e George E. Cirlin. "Confirmation of spontaneous doping of GaN nanowires grown on vicinal SiC/Si substrate by electron beam induced current mapping". Kondensirovannye sredy i mezhfaznye granitsy = Condensed Matter and Interphases 25, n. 4 (12 ottobre 2023): 526–31. http://dx.doi.org/10.17308/kcmf.2023.25/11474.

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Abstract (sommario):

This study is devoted to the confirmation of spontaneous doping of GaN nanowires grown on vicinal SiC/Si hybrid substrates by electron beam induced current mapping. GaN nanowires (NWs) were grown on singular and vicinal SiC/Si substrates by molecular beam epitaxy with nitrogen plasma activation. The morphological properties of the NWs were studied by scanning electron microscopy. The electrophysical properties of the obtained nanostructures were studied by electron beam induced current mapping. By electron beam induced current mapping, we confirmed the spontaneous doping of the GaN NWs grown on vicinal SiC/Si wafers. It was also shown that the GaN NWs grown on singular SiC/Si substrates did not exhibit an induced current signal, indicating that they were not doped

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48

Honda, Y., T. Ishikawa, Y. Nishimura, M. Yamaguchi e N. Sawaki. "HVPE Growth of GaN on a GaN Templated (111) Si Substrate". physica status solidi (c), n. 1 (2003): 107–11. http://dx.doi.org/10.1002/pssc.200390001.

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49

Bessolov V. N., Konenkova E. V. e Rodin S. N. "Initial stages of growth of the GaN(11\=22) layer on a nano-structured Si(113) substrate". Semiconductors 57, n. 1 (2023): 3. http://dx.doi.org/10.21883/sc.2023.01.55614.3994.

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Abstract (sommario):

Scanning electron microscopy was used to study of the initial stages of the formation of a semipolar GaN(1122) layer during Metalorganic Chemical Vapor Deposition on Si(113) substrates, on the surface of which U-shaped grooves with element sizes <100 nm (NP-Si(113)) were formed. It was found that NP-Si(113) substrates with a buffer AlN layer stimulate the formation of islands faceted by the planes m-GaN, c-GaN. It is shown that there is a predominant growth of the m-GaN facet in comparison with c-GaN.The experimental results correspond to the Gibbs--Curie--Wolff selection principle, but taking into account elastic stresses in the c-GaN plane. Keywords: semipolar gallium nitride, nano-structured substrate, silicon.

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50

Hu, F. R., R. Ito, Y. Zhao e K. Hane. "GaN-Si-MEMS structure fabricated from nano-column GaN quantum well crystal grown on Si substrate". physica status solidi (c) 5, n. 6 (maggio 2008): 1941–43. http://dx.doi.org/10.1002/pssc.200778497.

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