Добірка наукової літератури з теми "Ohmic and injection barrier transitions"
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Статті в журналах з теми "Ohmic and injection barrier transitions"
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Bae, Geun Yeol, Jinsung Kim, Junyoung Kim, Siyoung Lee, and Eunho Lee. "MoTe2 Field-Effect Transistors with Low Contact Resistance through Phase Tuning by Laser Irradiation." Nanomaterials 11, no. 11 (October 22, 2021): 2805. http://dx.doi.org/10.3390/nano11112805.
Повний текст джерелаАнотація:
Due to their extraordinary electrical and physical properties, two-dimensional (2D) transition metal dichalcogenides (TMDs) are considered promising for use in next-generation electrical devices. However, the application of TMD-based devices is limited because of the Schottky barrier interface resulting from the absence of dangling bonds on the TMDs’ surface. Here, we introduce a facile phase-tuning approach for forming a homogenous interface between semiconducting hexagonal (2H) and semi-metallic monoclinic (1T′) molybdenum ditelluride (MoTe2). The formation of ohmic contacts increases the charge carrier mobility of MoTe2 field-effect transistor devices to 16.1 cm2 V−1s−1 with high reproducibility, while maintaining a high on/off current ratio by efficiently improving charge injection at the interface. The proposed method enables a simple fabrication process, local patterning, and large-area scaling for the creation of high-performance 2D electronic devices.
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Hamui, Leon, Maria Elena Sánchez-Vergara, Ricardo Corona-Sánchez, Omar Jiménez-Sandoval, and Cecilio Álvarez-Toledano. "Innovative Incorporation of Poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) as Hole Carrier Transport Layer and as Anode for Organic Solar Cells Performance Improvement." Polymers 12, no. 12 (November 27, 2020): 2808. http://dx.doi.org/10.3390/polym12122808.
Повний текст джерелаАнотація:
In this work, we present a comparative study of benzoid poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) as electrode and as hole carrier transport layer (HTL) in the manufacture of organic photovoltaic devices using Fischer metal-carbene complexes. The performance of the different devices was evaluated for solar cell applications. Scanning electronic microscopy (SEM) and X-ray diffraction (XRD) were used to characterize the thin films that integrated the devices. A more ordered and crystallized active film microstructure is observed when using benzoid PEDOT:PSS as nucleation layer. The optical gap for both direct and indirect electronic transitions was evaluated from ultraviolet-visible spectroscopy data (UV-vis), as well as the absorption coefficient (α), and the values are in the range of 2.10–2.93 eV. Photovoltaic devices with conventional architecture, using two different chromium carbenes as active layers, were manufactured, and their electrical behavior was studied. The devices were irradiated with different wavelengths between the infrared and ultraviolet regions of the electromagnetic spectrum. Using the PEDOT:PSS film as hole carrier transport layer (HTL) decreases the slope on the ohmic and space charge limited current (SCLC) regions and eliminates the trap-charge limited current (T-CLC) mechanism. Furthermore, a saturation current of ~1.95 × 10−10 A and higher current values ~1.75 × 10−2 A at 4 V, ~4 orders in magnitude larger were observed. The PEDOT:PSS films as HTL in the devices reduced the injection barrier, thus showing a better performance than as anodes in this type of organic solar cells.
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Huang, Yaren, Jonas Buettner, Benedikt Lechner, and Gerhard Wachutka. "The Impact of Non-Ideal Ohmic Contacts on the Performance of High-Voltage SiC MPS Diodes." Materials Science Forum 963 (July 2019): 553–57. http://dx.doi.org/10.4028/www.scientific.net/msf.963.553.
Повний текст джерелаАнотація:
The wide band gap of SiC semiconductor devices constitutes a serious challenge to build good Ohmic contacts on the surface of the p-type material. This is reflected in the numerical analysis of ”realistic” devices, where we have to cope with serious problems, such as a shifting threshold voltage, reduced forward conductivity, and no noticeable conductivity modulation by minority carrier injection from p+-emitters, in matching measured data with simulation results, as a consequence of the significant impact of non-ideal poor Ohmic contacts. In this work, we used a Schottky contact model together with a barrier tunneling model, instead of common ideal Ohmic contact model, to simulate the non-ideal Ohmic contact on SiC MPS diodes. Based on this approach, the I-V characteristics of real Ohmic contacts can be reproduced in high-fidelity simulations, providing us physical insight of the observed operational behavior.
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Xu, Hongyi, Na Ren, Jiupeng Wu, Zhengyun Zhu, Qing Guo, and Kuang Sheng. "The Impact of Process Conditions on Surge Current Capability of 1.2 kV SiC JBS and MPS Diodes." Materials 14, no. 3 (January 31, 2021): 663. http://dx.doi.org/10.3390/ma14030663.
Повний текст джерелаАнотація:
This paper demonstrated the impact of process conditions on the surge current capability of 1.2 kV SiC junction barrier Schottky diode (JBS) and merged PiN Schottky diode (MPS). The influence of ohmic contact and defect density produced by implantation was studied in the simulation. The device fabricated with high temperature implantation had less defect density in the implant region compared with room temperature implantation, which contributed to higher hole injection in surge current mode and 20% surge capability improvement. In addition, with lower P+ ohmic contact resistance, the device had higher surge capability. When compared to device fabrication with a single Schottky metal layer in the device active area, adding additional P+ ohmic contact on top of the P+ regions in the device active area resulted in the pn junctions sharing a greater portion of surge current, and improved the devices’ surge capability by ~10%.
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López-Galán, Oscar A., Manuel Ramos, John Nogan, Alejandro Ávila-García, Torben Boll, and Martin Heilmaier. "The electronic states of ITO–MoS2: Experiment and theory." MRS Communications 12, no. 2 (December 16, 2021): 137–44. http://dx.doi.org/10.1557/s43579-021-00126-9.
Повний текст джерелаАнотація:
AbstractWe report a combination of experimental results with density functional theory (DFT) calculations to understand electronic structure of indium tin oxide and molybdenum disulfide (ITO–MoS2) interface. Our results indicate ITO and MoS2 conform an n-type Schottky barrier of c.a. − 1.0 eV due to orbital interactions; formation of an ohmic contact is caused by semiconducting and metal behavior of ITO as a function of crystal plane orientation. ITO introduces energy levels around the Fermi level in all interface models in the Γ-Μ-Κ-Γ path. The resulted Van der Waals interface and the values of Schottky barrier height enhance electron carrier injection. Graphical abstract
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Pérez, R., Narcis Mestres, Dominique Tournier, Xavier Jordá, Phillippe Godignon, and Miquel Vellvehi. "Temperature Dependence of 4H-SiC JBS and Schottky Diodes after High Temperature Treatment of Contact Metal." Materials Science Forum 483-485 (May 2005): 945–48. http://dx.doi.org/10.4028/www.scientific.net/msf.483-485.945.
Повний текст джерелаАнотація:
In this work we demonstrate performant characteristics of 1.2KV Schottky, Junction Barrier Schottky (JBS) and implanted PN diodes processed on the same 4H-SiC wafer. A bi-layer Ni/Ti scheme for the contact metallisation submitted to high temperature rapid thermal anneals is proved to form good ohmic contact on p+ implanted areas while maintaining good Schottky characteristics on lightly doped n-type regions. I-V characteristics have been evaluated from room temperature up to 560K. At room temperature, Schottky diodes have slightly better specific onresistance, but when working temperature is increased, the JBS diode exhibits better characteristics due to the temperature dependent activation of bipolar current injection from the p+ grid. From reverse measurements, the JBS diodes showed lower leakage current and higher breakdown voltages in comparison to that of the Schottky diodes in the whole range of temperatures.
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Cha, Jung-Suk, Da-hoon Lee, Kee-Baek Sim, Tae-Ju Lee, Tae-Yeon Seong, and Hiroshi Amano. "Inhomogeneous Barrier Height Characteristics of n-Type AlInP for Red AlGaInP-Based Light-Emitting Diodes." ECS Journal of Solid State Science and Technology 11, no. 3 (March 1, 2022): 035007. http://dx.doi.org/10.1149/2162-8777/ac5d66.
Повний текст джерелаАнотація:
For micro-light-emitting diode (LED)-based display applications, such as virtual reality and augmented reality, high-performance Ohmic contacts (namely, the improvement of current injection efficiency) is vital to the realization of high-efficiency micro-LEDs. The surface Fermi level pinning characteristics could be comprehended in terms of the relation between work function of metals (ΦM) and Schottky barrier height (SBH, ΦB). In this study, we have investigated the surface Fermi level pinning characteristics of (001) n-AlInP surfaces by employing Schottky diodes with different metals. With an increase in the temperature, ΦB increases linearly and ideality factors (n) decreases. This behavior is related to the barrier height inhomogeneity. Inhomogeneity-model-based ΦB is evaluated to be in the range of 0.86–1.30 eV, which is dependent on the metal work functions and are similar to those measured from capacitance-voltage relation. Further, The S-parameter, the relation between ΦB and ΦM (dΦB/dΦM), is 0.36. This is indicative of the partial pinning of the surface Fermi level at the surface states placed at 0.95 eV below the conduction band. Furthermore, it is also shown that (NH4)2S-passivation results in an increases the mean SBH and the S-parameter (e.g., 0.52).
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Squeo, Benedetta Maria, Wojciech Mróz, Umberto Giovanella, and Mariacecilia Pasini. "Anionic Low Band Gap-Conjugated Polyelectrolytes as Hole-Transporting Layer in Optoelectronics Devices." Chemistry Proceedings 3, no. 1 (November 14, 2020): 18. http://dx.doi.org/10.3390/ecsoc-24-08406.
Повний текст джерелаАнотація:
In the last years, interfacial engineering has played a critical role in promoting the performance of optoelectronic devices as organic solar cells (OSC) and organic light-emitting diodes (OLEDs) since interfacial layers help to form an ohmic contact between the electrodes and the active layers, which is of great importance for charge collection/injection. Conjugated polyelectrolytes (CPEs), which are conjugated polymers bearing side-chain ionic functionalities such as anionic, cationic, or zwitterionic groups, have emerged as a new class of interfacial materials in thin film-based electronic devices thanks to their ability to reduce the barrier between electrode and active layer. In view of this, we designed and synthesized two novel low bandgap anionic copolymers with different anionic pendant groups and different conjugated backbones to obtain hole-transporting layer (HTL) materials as an alternative to commonly used poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate). The functional behavior of these copolymers as anode modifiers is herein preliminarily investigated in an OLED prototype.
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Fatahi, Negin, Arash Boochani, Shahram Solaymani, Elmira Sartipi, and Farzad Ahmadian. "The band offset barrier and optical properties calculation of Co2VGa/GaAs(001) interfaces: A DFT study." International Journal of Modern Physics B 32, no. 01 (January 8, 2018): 1750270. http://dx.doi.org/10.1142/s0217979217502708.
Повний текст джерелаАнотація:
The structural, electronic, optical properties and band offsets of Co2VGa/GaAs(001) interfaces are discussed within the framework of density functional theory (DFT) using the FP-LAPW method, and the exchange-correlation potential is approximated by GGA. All interface structures are stable in the energy point of view, however the V–Ga/As case is found to be more stable than the others. A remarkable potential difference ([Formula: see text]V) appeared in all the interfaces, so the Co2VGa/GaAs(001) interfaces are good candidates for electron injection. In all the cases, there is no full spin polarization at the Fermi level, but high CBO and [Formula: see text] coefficients make them promising candidates for spin injection in the transport devices. Optical studies confirm the high metallic treatment of these interfaces as the main electron transitions had occurred in the infrared and visible regions. The real parts of the dielectric function in the x-direction indicate the different behaviors of “Co–Co/As and V–Ga/Ga” and “Co–Co/Ga and V–Ga/As” in the infrared area. In addition, the plasmon frequencies had occurred at high UV energies.
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Vermare, L., P. Hennequin, C. Honoré, M. Peret, G. Dif-Pradalier, X. Garbet, J. Gunn, et al. "Formation of the radial electric field profile in the WEST tokamak." Nuclear Fusion 62, no. 2 (December 16, 2021): 026002. http://dx.doi.org/10.1088/1741-4326/ac3c85.
Повний текст джерелаАнотація:
Abstract Sheared flows are known to reduce turbulent transport by decreasing the correlation length and/or intensity of turbulent structures. The transport barrier that takes place at the edge during improved regimes such as H mode, corresponds to the establishment of a large shear of the radial electric field. In this context, the radial shape of the radial electric field or more exactly of the perpendicular E × B velocity appears as a key element in accessing improved confinement regimes. In this paper, we present the radial profile of the perpendicular velocity measured using Doppler back-scattering system at the edge of the plasma, dominated by the E × B velocity, during the first campaigns of the WEST tokamak. It is found that the radial velocity profile is clearly more sheared in lower single null configuration (with the B × ∇B magnetic drift pointing toward the active X-point) than in upper single null configuration for ohmic and low current plasmas (B = 3.7 T and q 95 = 4.7), consistently with the expectation comparing respectively ‘favourable’ versus ‘unfavourable’ configuration. Interestingly, this tendency is sensitive to the plasma current and to the amount of additional heating power leading to plasma conditions in which the E × B velocity exhibits a deeper well in USN configuration. For example, while the velocity profile exhibits a clear and deep well just inside the separatrix concomitant with the formation of a density pedestal during L–H transitions observed in LSN configuration, deeper E r wells are observed in USN configuration during similar transitions with less pronounced density pedestal.
Дисертації з теми "Ohmic and injection barrier transitions"
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Дмитрієв, Вадим Сергійович. "Омічні та інжектуючі бар’єрні переходи до арсеніду галію". Doctoral thesis, Київ, 2019. https://ela.kpi.ua/handle/123456789/29304.
Повний текст джерелаАнотація:
Роботу виконано на кафедрі мікроелектронних інформаційних систем Інженерного інституту Запорізького національного університету Міністерства освіти і науки України.Дисертація на здобуття наукового ступеня кандидата технічних наук за спеціальністю 05.27.06 - Технологія, обладнання та виробництво електронної техніки. – Інженерний інститут Запорізького національного університету, Національний технічний університет України «Київський політехнічний інститут імені Ігоря Сікорського», 2019. Дисертаційну роботу присвячено розробці технології відтворюваного отримання омічних та інжектуючих бар’єрних переходів на основі срібла до арсеніду галію n-типу провідності. Розроблено технологію відтворюваного отримання омічних контактів Ag-Ge-In/n-n+GaAs, яка забезпечує лінійну ВАХ, коефіцієнт інжекції γ=0,07…0,00, контактний опір (5…7)∙10-5 Ом∙см2. Розроблено технологію відтворюваного отримання інжектуючих бар`єрних переходів Ag/n-n+GaAs з висотою потенційного бар’єру 0,98 В, коефіцієнтом інжекції γ =10-8, коефіцієнтом неідеальності η=1,087. Розроблені технології нанесення контактного матеріалу та режимів термообробки при створенні омічних та інжектуючих бар’єрних переходів рекомендуються до використання при виготовленні багатоелектродного МЕП-приладу з розширеними функціональними можливостями, до складу якого входять керуючі електроди, розташовані над областю розповсюдження біжучої хвилі.
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Satter, Md Mahbub. "Design and theoretical study of Wurtzite III-N deep ultraviolet edge emitting laser diodes." Diss., Georgia Institute of Technology, 2014. http://hdl.handle.net/1853/53042.
Повний текст джерелаАнотація:
Designs for deep ultraviolet (DUV) edge emitting laser diodes (LDs) based on the wurtzite III-nitride (III-N) material system are presented. A combination of proprietary and commercial advanced semiconductor LD simulation software is used to study the operation of III-N based DUV LDs theoretically. Critical factors limiting device performance are identified based on an extensive literature survey. A comprehensive design parameter space is investigated thoroughly with the help of advanced scripting capabilities. Several design strategies are proposed to eliminate the critical problems completely or partially.
A DUV LD design is proposed based exclusively on AlInN active layers grown epitaxially on bulk AlN substrates because AlInN offers a promising alternative to AlGaN for the realization of LDs and LEDs operating in the DUV regime. The proposed AlInN-based design also features a tapered electron blocking layer (EBL) instead of a homogeneous one. Tapered EBLs redistribute the interfacial polarization charge volumetrically throughout the entire EBL thickness via compositional grading, and eliminate the parasitic inversion layer charge.
AlGaN based DUV LD designs are explored also because at present, it may be difficult to grow AlInN epitaxially with superior crystalline quality. Polarization charge matching is proposed to improve electron and hole wavefunction overlap within the active region. Although the strategy of polarization charge matching has already been proposed in the literature to enhance performance of visible wavelength LEDs and LDs, the proposed design presents the first demonstration that polarization charge matching is also feasible for DUV LDs operating at sub-300 nm wavelengths.
A lateral current injection (LCI) LD design is proposed featuring polarization-charge-matched barriers and regrown Ohmic contacts to avoid a group of issues related to the highly inefficient p-type doping of wide bandgap III-N materials in vertical injection designs. The proposed design partially decouples the problem of electrical injection from that of optical confinement. Although the idea of an LCI LD design has been proposed in the literature in the 90s to be used as longer wavelength active sources in optoelectronic integrated circuits using GaInAsP/InP and related material systems, the proposed design is the first theoretical demonstration that this concept can be applied to DUV LDs based on III-N material system.
To solve the problem of hole transport in vertical injection designs, a DUV LD design based exclusively on AlGaN material system is presented, featuring an inverse-tapered p-waveguide layer instead of an EBL. Several EBL designs are investigated, and compared with conventionally-tapered EBL design. Through judicious volumetric redistribution of fixed negative polarization charge, inverse tapering may be exploited to achieve nearly flat valence band profiles free from barriers to hole injection into the active region, in contrast to conventional designs. Numerical simulations demonstrate that the inverse tapered strategy is a viable solution for efficient hole injection in vertical injection DUV LDs operating at shorter wavelengths (< 290 nm).
Тези доповідей конференцій з теми "Ohmic and injection barrier transitions"
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Wroblewski, Donald, Onomitra Ghosh, Annie Lum, David Willoughby, Michael VanHout, Kristina Hogstrom, Soumendra N. Basu, and Michael Gevelber. "Modeling and Parametric Analysis of Plasma Spray Particle State Distribution for Deposition Rate Control." In ASME 2008 International Mechanical Engineering Congress and Exposition. ASMEDC, 2008. http://dx.doi.org/10.1115/imece2008-68752.
Повний текст джерелаАнотація:
Plasma spray for depositing thermal barrier coatings features large distributions of particle states that result in significant variations in coating quality. These variations arise from distributions of particle sizes, large spatial gradients of plasma thermal-fluid fields, and temporal variations of the arc and jet. This paper describes a simplified approach for studying how particle state distributions are influenced by torch conditions and powder distributions, and the implications for deposition rate monitoring and control. The approach combines a simplified jet model with a more detailed particle model. The important fluid-thermal spatial gradients in the plasma jet are captured using a three zone model: a core region, modeled by growth of a turbulent shear layer around a laminar core, a transition region and a similarity region. Plasma-particle momentum and thermal interactions, particle phase transitions, internal particle temperature gradients, and collapse of in-flight hollow particles have been modeled using a multi-lumped particle model. Effects of distributions of particle size, particle morphology, injection velocity, and carrier gas flow were studied for YSZ spray in an Ar-He plasma. The results provide guidance on sensor design and operation and on approaches for plume location control.