Journal articles: 'Silicon nanocrystals'

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Natrayan, L., P. V. Arul Kumar, S. Kaliappan, S. Sekar, Pravin P. Patil, R. Jayashri, and E. S. Esakki Raj. "Analysis of Incorporation of Ion-Bombarded Nickel Ions with Silicon Nanocrystals for Microphotonic Devices." Journal of Nanomaterials 2022 (August 16, 2022): 1–7. http://dx.doi.org/10.1155/2022/5438084.

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Nanotechnology is playing a greater role in biomedical engineering. Microphotonic technology is on another side, having faster growth with more requirements. The nanocrystals are a part of nanotechnology which uses silicon for manufacturing. These silicon nanocrystals have the optical property mostly used in microphotonic devices. Silicon nanocrystals are of biocompatibility with less toxicity. Therefore, the advancement in the silicon nanocrystal helps develop more microphotonic devices for biological purposes. One critical factor of silicon nanocrystal is the surface defects or surface imperfections. Surface passivation is the method employed for rectifying this disadvantage of silicon nanocrystal. Another major thing is that silicon nanocrystals are size dependent. So proper variation on the surface is required for yielding high performance of the nanocrystal. After characterizing the surface of the silicon nanocrystal, ion bombardment can occur. Nickel is a lustrous white chemical element which is less reactive when it is of a smaller size. So ion bombardment of nickel ion on the surface of the silicon nanocrystal can be done to improvise the performance of the microphotonic devices. Nearly there is an excess of 20 a.u. of photoluminescence intensity yielded. The relative fluorescence is also increased by 150 a.u. This research work enhanced the silicon nanocrystal using ion bombardment of nickel ion, which increased energy traps resulting in more intensities.

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Ferraioli, L., M. Wang, G. Pucker, D. Navarro-Urrios, N. Daldosso, C. Kompocholis, and L. Pavesi. "Photoluminescence of Silicon Nanocrystals in Silicon Oxide." Journal of Nanomaterials 2007 (2007): 1–5. http://dx.doi.org/10.1155/2007/43491.

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Recent results on the photoluminescence properties of silicon nanocrystals embedded in silicon oxide are reviewed and discussed. The attention is focused on Si nanocrystals produced by high-temperature annealing of silicon rich oxide layers deposited by plasma-enhanced chemical vapor deposition. The influence of deposition parameters and layer thickness is analyzed in detail. The nanocrystal size can be roughly controlled by means of Si content and annealing temperature and time. Unfortunately, a technique for independently fine tuning the emission efficiency and the size is still lacking; thus, only middle size nanocrystals have high emission efficiency. Interestingly, the layer thickness affects the nucleation and growth kinetics so changing the luminescence efficiency.

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Shen, Hao, Huabao Shang, Yuhan Gao, Deren Yang, and Dongsheng Li. "Efficient Sensitized Photoluminescence from Erbium Chloride Silicate via Interparticle Energy Transfer." Materials 15, no. 3 (January 30, 2022): 1093. http://dx.doi.org/10.3390/ma15031093.

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In this study, we prepare Erbium compound nanocrystals and Si nanocrystal (Si NC) co-embedded silica film by the sol-gel method. Dual phases of Si and Er chloride silicate (ECS) nanocrystals were coprecipitated within amorphous silica. Effective sensitized emission of Er chloride silicate nanocrystals was realized via interparticle energy transfer between silicon nanocrystal and Er chloride silicate nanocrystals. The influence of density and the distribution of sensitizers and Er compounds on interparticle energy transfer efficiency was discussed. The interparticle energy transfer between the semiconductor and erbium compound nanocrystals offers some important insights into the realization of efficient light emission for silicon-based integrated photonics.

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Zatryb, G., A. Podhorodecki, J. Misiewicz, J. Wojcik, and P. Mascher. "Size-Dependent Indirect Excitation of Trivalent Er Ions via Si Nanocrystals Embedded in a Silicon-Rich Silicon Oxide Matrix Deposited by ECR-PECVD." Journal of Nanotechnology 2009 (2009): 1–5. http://dx.doi.org/10.1155/2009/769142.

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Silicon nanocrystals (Si-nc) embedded in a silicon-rich silicon oxide matrix codoped withEr3+ions have been fabricated by electron-cyclotron plasma-enhanced chemical vapor deposition. Indirect excitation of erbium photoluminescence via silicon nanocrystals has been obtained within a broad pump wavelength range. The influence of different nanocrystal sizes on the excitation transfer from the Si-nc toEr3+ions is discussed.

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Komarov, Fadey, Altynay Togambayeva, Ludmila Vlasukova, Irina Parkhomenko, Oleg Milchanin, Maksim Makhavikov, and Murat Tolkynay. "Ion-Beam Synthesis of InSb Nanocrystals in Si Matrix." Advanced Materials Research 679 (April 2013): 9–13. http://dx.doi.org/10.4028/www.scientific.net/amr.679.9.

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The results of structural and optical investigation of crystalline Si with embedded InSb nanocrystals are reported. These nanocrystals were synthesized in silicon matrix by means of high-fluence “hot” implantation of Sb and In ions followed by thermal treatment. TEM gives an evidence of nanocrystal formation in implanted and annealed samples as well as an existence of microtwins and dislocation-type defects and substantial residual mechanical strains. We have identified nanocrystals as InSb from RS data. Mechanical strains in “silicon – InSb nanocrystals” system have been evaluated, too.

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Li, Zhaohan, Zachary L. Robinson, Paolo Elvati, Angela Violi, and Uwe R. Kortshagen. "Distance-dependent resonance energy transfer in alkyl-terminated Si nanocrystal solids." Journal of Chemical Physics 156, no. 12 (March 28, 2022): 124705. http://dx.doi.org/10.1063/5.0079571.

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Understanding and controlling the energy transfer between silicon nanocrystals is of significant importance for the design of efficient optoelectronic devices. However, previous studies on silicon nanocrystal energy transfer were limited because of the strict requirements to precisely control the inter-dot distance and to perform all measurements in air-free environments to preclude the effect of ambient oxygen. Here, we systematically investigate the distance-dependent resonance energy transfer in alkyl-terminated silicon nanocrystals for the first time. Silicon nanocrystal solids with inter-dot distances varying from 3 to 5 nm are fabricated by varying the length and surface coverage of alkyl ligands in solution-phase and gas-phase functionalized silicon nanocrystals. The inter-dot energy transfer rates are extracted from steady-state and time-resolved photoluminescence measurements, enabling a direct comparison to theoretical predictions. Our results reveal that the distance-dependent energy transfer rates in Si NCs decay faster than predicted by the Förster mechanism, suggesting higher-order multipole interactions.

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YıImaz, D. E., C. Bulutay, and T. Çagın. "Atomistic Structure Simulation of Silicon Nanocrystals Driven with Suboxide Penalty Energies." Journal of Nanoscience and Nanotechnology 8, no. 2 (February 1, 2008): 635–39. http://dx.doi.org/10.1166/jnn.2008.a117.

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The structural control of silicon nanocrystals embedded in amorphous oxide is currently an important technological problem. In this work, an approach is presented to simulate the structural behavior of silicon nanocrystals embedded in amorphous oxide matrix based on simple valence force fields as described by Keating-type potentials. After generating an amorphous silicon-rich-oxide, its evolution towards an embedded nanocrystal is driven by the oxygen diffusion process implemented in the form of a Metropolis algorithm based on the suboxide penalty energies. However, it is observed that such an approach cannot satisfactorily reproduce the shape of annealed nanocrystals. As a remedy, the asphericity and surface-to-volume minimization constraints are imposed. With the aid of such a multilevel approach, realistic-sized silicon nanocrystals can be simulated. Prediction for the nanocrystal size at a chosen oxygen molar fraction matches reasonably well with the experimental data when the interface region is also accounted. The necessity for additional shape constraints suggests the use of more involved force fields including long-range forces as well as accommodating different chemical environments such as the double bonds.

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Efremov, M. D., Vladimir A. Volodin, D. V. Marin, Sofia A. Arzhannikova, M. G. Ivanov, S. V. Gorajnov, A. I. Korchagin, et al. "Blue Photoluminescence from Quantum Size Silicon Nanopowder." Solid State Phenomena 108-109 (December 2005): 65–70. http://dx.doi.org/10.4028/www.scientific.net/ssp.108-109.65.

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Silicon nanopowders were produced using electron-beam-induced evaporation of bulk silicon ingots in various gas atmosphere. Optical properties of the nanopowders were studied with the use of photoluminescence and Raman spectroscopy techniques. Photoluminescence peaks in the visible region of the spectrum have been detected at room temperature in silicon nanopowders, produced in argon gas atmosphere. Strong short-wavelength shift of the photoluminescence peaks can be result of quantum confinement effect for electrons and holes in small silicon nanocrystals (down to 2 nm in diameter). The size of silicon nanocrystals was estimated from Raman spectroscopy data. The calculated in frame of effective mass model optical gaps for silicon nanocrystals of spherical shape are in good correlation with experimental photoluminescence data. The attempts of deposition of silicon nanocrystal films from the nanopowders on silicon substrates were carried out.

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Zhigunov, D. M., A. A. Popov, Yu M. Chesnokov, A. L. Vasiliev, A. M. Lebedev, I. A. Subbotin, S. N. Yakunin, O. A. Shalygina, and I. A. Kamenskikh. "Near-IR Emitting Si Nanocrystals Fabricated by Thermal Annealing of SiNx/Si3N4 Multilayers." Applied Sciences 9, no. 22 (November 6, 2019): 4725. http://dx.doi.org/10.3390/app9224725.

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Silicon nanocrystals in silicon nitride matrix are fabricated by thermal annealing of SiNx/Si3N4 multilayered thin films, and characterized by transmission electron microscopy, X-ray reflectivity and diffraction analysis, photoluminescence and X-ray photoelectron spectroscopy techniques. Si nanocrystals with a mean size of about 4 nm are obtained, and their properties are studied as a function of SiNx layer thickness (1.6–2 nm) and annealing temperature (900–1250 °C). The effect of coalescence of adjacent nanocrystals throughout the Si3N4 barrier layers is observed, which results in formation of distinct ellipsoidal-shaped nanocrystals. Complete intermixing of multilayered film accompanied by an increase of nanocrystal mean size for annealing temperature as high as 1250 °C is shown. Near-IR photoluminescence with the peak at around 1.3–1.4 eV is detected and associated with quantum confined excitons in Si nanocrystals: Photoluminescence maximum is red shifted upon an increase of nanocrystal mean size, while the measured decay time is of order of microsecond. The position of photoluminescence peak as compared to the one for Si nanocrystals in SiO2 matrix is discussed.

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Choi, Seong Jae, Dong Kee Yi, Jae-Young Choi, Jong-Bong Park, In-Yong Song, Eunjoo Jang, Joo In Lee, et al. "Spatial Control of Quantum Sized Nanocrystal Arrays onto Silicon Wafers." Journal of Nanoscience and Nanotechnology 7, no. 12 (December 1, 2007): 4285–93. http://dx.doi.org/10.1166/jnn.2007.884.

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Monolayer arrays of monodispersed nanocrystals (<10 nm) onto three dimensional (3D) substrates have considerable potential for various engineering applications such as highly integrated memory devices, solar cells, biosensors and photo and electro luminescent displays because of their highly integrated features with nanocrystal homogeneity. However, most reports on nanocrystal arrays have focused on two dimensional (2D) flat substrates, and the production of wafer-scale monolayer arrays is still challenging. Here we address the feasibility of arraying nanocrystal monolayers in wafer-scale onto 3D substrates. We present both metal (Pd) and semiconductor (CdSe) nanocrystals arrayed in monolayer onto trenched silicon wafers (4 inch diameter) using a facile electrostatic adsorption scheme. In particular, CdSe nanocrystal arrays in the trench well showed superior luminescent efficiency compared to those onto the protruded trench flat, due to the densely arrayed CdSe nanocrystals in the vertical direction. Furthermore, the surface coverage controllability was investigated using a 2D silicon substrate. Our approach can be applied to generate highly efficient displays, memory chips and integrated sensing devices.

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Igo A.V. "The degree of polarization of Raman scattering of light in silicon nanocrystals." Semiconductors 56, no. 8 (2022): 556. http://dx.doi.org/10.21883/sc.2022.08.54113.30.

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Raman scattering of light (RS) on an array of oriented silicon nanocrystals was studied experimentally. The angular dependence of the intensity of the polarized components of the RS was measured and the parameter of the degree of polarization of scattered light was determined. It was found that the degree of polarization of the RS is related to the size of the nanocrystals in the samples. An array of nanocrystals with the same crystallographic orientation was obtained by thermal annealing of a silicon single crystal damaged by ion implantation. During thermal annealing of the sample, the crystallinity of the layer is restored not simultaneously in the entire damaged volume, but in the form of nanocrystals separated by amorphous area. All the clusters formed have the same crystallographic orientation of the original single crystal. The features of the degree of polarization of the RS in nanocrystals are associated with the quantum-mechanical uncertainty of the phonon wave vector and the uncertainty of the phonon direction in a limited volume of the nanocrystal. The relations linking the degree of polarization of the RS with the size of nanocrystals are obtained. A technique for determining the size of nanocrystals by measuring the degree of polarization of the RS is discussed. Keywords: Raman scattering of light, silicon, nanocrystals, ion implantation, annealing, amorphous phase.

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CHAN, M. Y., and P. S. LEE. "FABRICATION OF SILICON NANOCRYSTALS AND ITS ROOM TEMPERATURE LUMINESCENCE EFFECTS." International Journal of Nanoscience 05, no. 04n05 (August 2006): 565–70. http://dx.doi.org/10.1142/s0219581x06004802.

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Silicon ( Si ) nanocrystals have been considered a good candidate for flash memory device and nanophotonic applications. The fabrication of nanocrystal memory is to form uniform, small size and high density quantum dots. In this study, nanometer-scale silicon quantum dots have been fabricated on ultrathin silicon oxide layer using amorphous silicon (a- Si ) deposition followed by various annealing treatments. The a- Si layers were crystallized using furnace annealing, laser annealing and rapid thermal annealing (RTA). After annealing to form nanometer-sized crystallites, silicon wet etch was carried out to isolate the nanocrystals. The size, uniformity and density of the nanocrystals were successfully controlled by different annealing treatments. The mean dot height and mean dot diameter is 1–5 nm and 2–5 nm, respectively. Lateral growth of the silicon dots was further controlled by systemic variations of the annealing conditions. It is found that the annealed a- Si films exhibit room temperature visible photoluminescence (PL) resulting from the formation of nanometer-sized crystallites. Selective wet etch and Secco-etch treatment increased the PL efficiency that is useful for nanophotonics applications. The feasibility of quantum dot formation using ultra thin amorphous Si films is demonstrated in this work.

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Wang, Li, Hong Fang Sun, Hui Hua Zhou, and Jing Zhu. "Self-Assembly Growth and Size Control of Silver Nanocrystals for Nonvolatile Memory Applications." Materials Science Forum 610-613 (January 2009): 585–90. http://dx.doi.org/10.4028/www.scientific.net/msf.610-613.585.

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A film with a single-layer of size controlled silver nanocrystals embedded in silicon dioxide (SiO2) dielectric film by magnetic sputtering has been fabricated for nonvolatile memory applications. The effects of sputtering power, deposition time and substrate temperature on Ag nanocrystals formation were investigated. Transmission electron microscopy (TEM) images showed the as-prepared Ag nanocrystals had high uniformity in their size and distribution. The relationship between Ag nanocrystal size, density and electron storage capability as well as date retention time has been discussed.

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Benassayag, G., M. Shalchian, Jeremie Grisolia, Caroline Bonafos, S. M. Atarodi, and A. Claverie. "From Continuous to Quantized Charging Phenomena in Few Nanocrystals MOS Structures." Solid State Phenomena 108-109 (December 2005): 25–32. http://dx.doi.org/10.4028/www.scientific.net/ssp.108-109.25.

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In this paper, we present a study on the contribution of silicon nanocrystals to the electrical transport characteristics of large (100 m x 100 m) and small (100 nm x 100 nm) metaloxide- semiconductor (MOS) capacitors at room temperature. A layer of silicon nanocrystals is synthesized within the oxide of these capacitors by ultra-low energy ion implantation and annealing. Several features including negative differential resistance (NDR), sharp current peaks and random telegraph signal (RTS) are demonstrated in the current-voltage and current-time characteristics of these capacitors. These features have been associated to charge storage in silicon nanocrystals and to the resulting Coulomb interaction between the stored charges and the tunneling current. Clear transition from a continuous response of large capacitors to a discrete response of small capacitors reveals the quantized nature of the charge storage phenomenon in these nanocrystalline dots. The effect of the nanocrystal density from nearly continuous layer to isolated nanodots is also presented.

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Curiel, Mario, Nicola Nedev, Judith Paz, Oscar Perez, Benjamin Valdez, David Mateos, Abraham Arias, et al. "UV Sensitivity of MOS Structures with Silicon Nanoclusters." Sensors 19, no. 10 (May 17, 2019): 2277. http://dx.doi.org/10.3390/s19102277.

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Selective UV sensitivity was observed in Metal-Oxide-Semiconductor structures with Si nanoclusters. Si nanocrystals and amorphous Si nanoparticles (a-Si NPs) were obtained by furnace annealing of SiOx films with x = 1.15 for 60 min in N2 at 1000 and 700 °C, respectively. XPS and TEM analysis prove phase separation and formation of Si nanocrystals in SiO2, while the a-Si NPs are formed in SiO1.7 matrix. Both types of structures show selective sensitivity to UV light; the effect is more pronounced in the structure with nanocrystals. The responsivity of the nanocrystal structure to 365 nm UV light is ~ 4 times higher than that to green light at 4 V applied to the top contact. The observed effect is explained by assuming that only short wavelength radiation generates photocarriers in the amorphous and crystalline nanoclusters.

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Gutsch, Sebastian, Daniel Hiller, Jan Laube, Margit Zacharias, and Christian Kübel. "Observing the morphology of single-layered embedded silicon nanocrystals by using temperature-stable TEM membranes." Beilstein Journal of Nanotechnology 6 (April 15, 2015): 964–70. http://dx.doi.org/10.3762/bjnano.6.99.

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We use high-temperature-stable silicon nitride membranes to investigate single layers of silicon nanocrystal ensembles by energy filtered transmission electron microscopy. The silicon nanocrystals are prepared from the precipitation of a silicon-rich oxynitride layer sandwiched between two SiO2 diffusion barriers and subjected to a high-temperature annealing. We find that such single layers are very sensitive to the annealing parameters and may lead to a significant loss of excess silicon. In addition, these ultrathin layers suffer from significant electron beam damage that needs to be minimized in order to image the pristine sample morphology. Finally we demonstrate how the silicon nanocrystal size distribution develops from a broad to a narrow log-normal distribution, when the initial precipitation layer thickness and stoichiometry are below a critical value.

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Cheong, Hea Jeong, Jung Hyun Kang, Jae Kwon Kim, and Kim Yong. "Growth of Highly Luminescent Silicon Nanocrystals by Rapid Thermal Chemical Vapor Deposition." Key Engineering Materials 277-279 (January 2005): 977–82. http://dx.doi.org/10.4028/www.scientific.net/kem.277-279.977.

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We investigate the growth of highly luminescent silicon nanocrystals by rapid thermal chemical vapor deposition (RTCVD), employing SiH4 and N2O as source gases. For [N2O]/[SiH4] = 7 ∼ 8 and a growth temperature of 650°C, we obtain the optimized deposition condition for silicon rich oxide (SRO) layer having highly luminescent Si nanocrystals after post-deposition annealing. The cross sectional transmission electron microscope investigation reveals the existence of Si nanocrystals in the SRO matrix. Thus, the photoluminescence (PL) from the SRO layer is attributed to the quantum confinement effect of carriers in Si nanocrystals. Based on a single layer growth study, we fabricate ultra-thin SRO/SiO2 superlattice having 25 periods on a 3-inch Si wafer. The superlattice has continuous thickness variation from the center to the edge positions of the Si wafer due to inherent wafer temperature variation during growth. Photoluminescence spectra show a systematic blue-shift from a thicker position (center position) to a thinner position (edge position) which is indicative of nanocrystal size control by SRO layer thickness in the superlattice.

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Fronya, Anastasiya A., Sergey V. Antonenko, Alexander Yu Kharin, Andrei V. Muratov, Yury A. Aleschenko, Sergey I. Derzhavin, Nikita V. Karpov, et al. "Tailoring Photoluminescence from Si-Based Nanocrystals Prepared by Pulsed Laser Ablation in He-N2 Gas Mixtures." Molecules 25, no. 3 (January 21, 2020): 440. http://dx.doi.org/10.3390/molecules25030440.

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Using methods of pulsed laser ablation from a silicon target in helium (He)-nitrogen (N2) gas mixtures maintained at reduced pressures (0.5–5 Torr), we fabricated substrate-supported silicon (Si) nanocrystal-based films exhibiting a strong photoluminescence (PL) emission, which depended on the He/N2 ratio. We show that, in the case of ablation in pure He gas, Si nanocrystals exhibit PL bands centered in the “red - near infrared” (maximum at 760 nm) and “green” (centered at 550 nm) spectral regions, which can be attributed to quantum-confined excitonic states in small Si nanocrystals and to local electronic states in amorphous silicon suboxide (a-SiOx) coating, respectively, while the addition of N2 leads to the generation of an intense “green-yellow” PL band centered at 580 nm. The origin of the latter band is attributed to a radiative recombination in amorphous oxynitride (a-SiNxOy) coating of Si nanocrystals. PL transients of Si nanocrystals with SiOx and a-SiNxOy coatings demonstrate nonexponential decays in the micro- and submicrosecond time scales with rates depending on nitrogen content in the mixture. After milling by ultrasound and dispersing in water, Si nanocrystals can be used as efficient non-toxic markers for bioimaging, while the observed spectral tailoring effect makes possible an adjustment of the PL emission of such markers to a concrete bioimaging task.

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Fermi, Andrea, Mirko Locritani, Gabriele Di Carlo, Maddalena Pizzotti, Stefano Caramori, Yixuan Yu, Brian A. Korgel, Giacomo Bergamini, and Paola Ceroni. "Light-harvesting antennae based on photoactive silicon nanocrystals functionalized with porphyrin chromophores." Faraday Discussions 185 (2015): 481–95. http://dx.doi.org/10.1039/c5fd00098j.

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Silicon nanocrystals functionalized with tetraphenylporphyrin Zn(ii) chromophores at the periphery perform as light harvesting antennae: excitation of the porphyrin units in the visible spectral region yields sensitized emission of the silicon nanocrystal core in the near infrared with a long lifetime (λ_max= 905 nm,τ= 130 μs). This result demonstrates that this hybrid material has a potential application as a luminescent probe for bioimaging.

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Tarasov, I. A., M. V. Rautskii, I. A. Yakovlev, and M. N. Volochaev. "Effect of epitaxial alignment on electron transport from quasi-two-dimensional iron silicide alpha-FeSi-=SUB=-2-=/SUB=- nanocrystals into p-Si(001)." Физика и техника полупроводников 52, no. 5 (2018): 523. http://dx.doi.org/10.21883/ftp.2018.05.45867.56.

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AbstractSelf-assembled growth of α-FeSi_2 nanocrystal ensembles on gold-activated and gold-free Si(001) surface by molecular beam epitaxy is reported. The microstructure and basic orientation relationship (OR) between the silicide nanocrystals and silicon substrate were analysed. The study reveals that utilisation of the gold as catalyst regulates the preferable OR of the nanocrystals with silicon and their habitus. It is shown that electron transport from α-FeSi2 phase into p-Si(001) can be tuned by the formation of (001)—or (111)—textured α-FeSi2 nanocrystals ensembles. A current-voltage characteristic of the structures with different preferable epitaxial alignment (α-FeSi_2(001)/Si(100) and α-FeSi_2(111)/Si(100)) shows good linearity at room temperature. However, it becomes non-linear at different temperatures for different ORs due to different Schottky barrier height governed by a particular epitaxial alignment of the α-FeSi_2/ p -Si interfaces.

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Terekhov, V. A., D. I. Tetelbaum, D. E. Spirin, K. N. Pankov, A. N. Mikhailov, A. I. Belov, A. V. Ershov, and S. Yu Turishchev. "X-ray absorption near-edge structure anomalous behaviour in structures with buried layers containing silicon nanocrystals." Journal of Synchrotron Radiation 21, no. 1 (December 17, 2013): 209–14. http://dx.doi.org/10.1107/s1600577513030026.

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Substructure and phase composition of silicon suboxide films containing silicon nanocrystals and implanted with carbon have been investigated by means of the X-ray absorption near-edge structure technique with the use of synchrotron radiation. It is shown that formation of silicon nanocrystals in the films' depth (more than 60 nm) and their following transformation into silicon carbide nanocrystals leads to abnormal behaviour of the X-ray absorption spectra in the elementary silicon absorption-edge energy region (100–104 eV) or in the silicon oxide absorption-edge energy region (104–110 eV). This abnormal behaviour is connected to X-ray elastic backscattering on silicon or silicon carbide nanocrystals located in the silicon oxide films depth.

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Aslanov, Leonid, Valery Zakharov, and Alexandr Yatsenko. "Sandwich-like flat freestanding silicon nanocrystals." Acta Crystallographica Section A Foundations and Advances 70, a1 (August 5, 2014): C945. http://dx.doi.org/10.1107/s2053273314090548.

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For the first time we have obtained the sandwich-like flat freestanding silicon nanocrystals (nc-Si) as a result of synthetic procedure in colloidal solution: the outer layers are formed by the perfluorophenyl ligands and flat silicon nanocrystal is located between two ligand layers. The fact of binding of the perfluorophenyl ligands to the surface of silicon nanoparticles is supported by FTIR, EDS and XPS spectroscopy. Concentrations of the elements observed on the surface of samples were calculated for the separate lines appeared to be as follows: Si 11.0, O 17.0, F 3.2, Morphology and structure of the synthesized Si-nanoparticles were studied by Transmission Electron Microscopy (TEM). The samples comprise two types of nanoparticles: spherical and flat (2D structures). The average diameter of spherical particles is 4.010.5 nm. Electron diffraction pattern (DP) demonstrates that spherical Si-nanoparticles are amorphous. Along with halo-like DP from spherical particles, the spot diffraction patterns from some areas are observed for flat nanoparticles which have the crystalline structure. The experimental DP is in a good agreement with the simulated diffraction pattern for cubic Si phase. analysis of electron diffraction data indicates that thickness of these particles is less than 10 nm. The size of these particles can reach 50 nm.The thickness of flat nanocrystals was evaluated by Atomic Force Microscopy (AFM) also: it appeared to be close to 3.3 nm in average what is thrice smaller than that determined by TEM. This difference will be discussed. Lamellar nanocrystals are possibly formed at the stage of replacement of the bromide ligands by perfluorophenyl groups and are the products of aggregation of spherical silicon nanoparticles in flat plates. Growth of the plates is caused by C...F specific interactions between the ligands, which result in formation of layers of the perfluorophenyl ligands due to their self-assembly in fluorophobic media.

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Leslie, Mitch. "Silicon nanocrystals shine." Journal of Cell Biology 202, no. 6 (September 16, 2013): 828. http://dx.doi.org/10.1083/jcb.2026iti3.

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Dhavse, Rasika, Kumar Prashant, Chetan Dabhi, Anand Darji, and R. M. Patrikar. "Modified ITAT Model for Data Retention in Nanocrystals Based Flash Memory Gate Stack." Journal of Nano Research 45 (January 2017): 1–11. http://dx.doi.org/10.4028/www.scientific.net/jnanor.45.1.

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This work applies combination of Direct Tunneling model and BSIM4 based ITAT model to explain the leakage of electrons from charged nanocrystals to p-type silicon substrate in data retention condition, for an ultra-thin tunnel oxide, low voltage programmable silicon nanocrystal based flash gate stack. Basic expressions of these models are modified to incorporate the nanocrystals related charge leakage in idle mode. The concept is supported by simulating these models and comparing them with the experimental data. Transition of electrons is considered as a result of Direct Tunneling and their trapping de-trapping via water related hydrogen traps. However, it is found that modified ITAT mechanism is the dominant one. Flat-band voltage shift profile fits accurately with the model with an extrapolated 10 years device lifetime without memory closure. 3 nm thick tunnel oxide and 100 nm sized nanocrystal fabrication with Electron Beam Lithography are main features of the devices.

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Ломов, А. А., А. В. Мяконьких, Ю. М. Чесноков, В. В. Денисов, А. Н. Кириченко, and В. Н. Денисов. "Дозовая зависимость формирования нанокристаллов в имплантированных гелием слоях кремния." Письма в журнал технической физики 44, no. 7 (2018): 39. http://dx.doi.org/10.21883/pjtf.2018.07.45883.17112.

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AbstractThe possibility of nanocrystal formation in silicon layers subjected to plasma-immersion helium-ion implantation at an energy of 5 keV has been proved for the first time. The effect of the implantation dose on the microstructure of the layers has been studied by X-ray reflectometry, transmission electron microscopy and Raman scattering. It has been established that the formation of silicon nanocrystals with dimensions of 10–20 nm is accompanied by a pronounced dependence on the ion flux and occurs at a dose of 5 × 10^17 cm^–2 with subsequent annealing at 700–800°C. The excessive dose has been shown to cause the destruction of the upper protective sublayer and the degradation of the optical properties of nanocrystals.

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Liu, Chin-Yi, and Uwe R. Kortshagen. "A Silicon Nanocrystal Schottky Junction Solar Cell produced from Colloidal Silicon Nanocrystals." Nanoscale Research Letters 5, no. 8 (May 20, 2010): 1253–56. http://dx.doi.org/10.1007/s11671-010-9632-z.

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Nama, Noor A., Mudar A. Abdulsattar, and Ahmed M. Abdul-Lettif. "Surface and Core Electronic Structure of Oxidized Silicon Nanocrystals." Journal of Nanomaterials 2010 (2010): 1–6. http://dx.doi.org/10.1155/2010/952172.

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Ab initio restricted Hartree-Fock method within the framework of large unit cell formalism is used to simulate silicon nanocrystals between 216 and 1000 atoms (1.6–2.65 nm in diameter) that include Bravais and primitive cell multiples. The investigated properties include core and oxidized surface properties. Results revealed that electronic properties converge to some limit as the size of the nanocrystal increases. Increasing the size of the core of a nanocrystal resulted in an increase of the energy gap, valence band width, and cohesive energy. The lattice constant of the core and oxidized surface parts shows a decreasing trend as the nanocrystal increases in a size that converges to 5.28 Ǻ in a good agreement with the experiment. Surface and core convergence to the same lattice constant reflects good adherence of oxide layer at the surface. The core density of states shows highly degenerate states that split at the oxygenated (001)-(1×1) surface due to symmetry breaking. The nanocrystal surface shows smaller gap and higher valence and conduction bands when compared to the core part, due to oxygen surface atoms and reduced structural symmetry. The smaller surface energy gap shows that energy gap of the nanocrystal is controlled by the surface part. Unlike the core part, the surface part shows a descending energy gap that proves its obedience to quantum confinement effects. Nanocrystal geometry proved to have some influence on all electronic properties including the energy gap.

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Ratajczak, Jacek, Krzysztof Hejduk, Marek Lipiński, Tadeusz Piotrowski, Mariusz Płuska, Adam Łaszcz, and Andrzej Czerwiński. "Study of Silicon Nanoparticles Formation in Silicon Nitride." Solid State Phenomena 186 (March 2012): 66–69. http://dx.doi.org/10.4028/www.scientific.net/ssp.186.66.

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We present results of the study on the silicon nanoparticles formation in multilayer silicon nitride structures. These structures consist of pairs of stoichiometric silicon nitride dielectric layers (SiNx) and silicon rich nitride layers (SRN). Silicon nanocrystals precipitate from the SRN layer during annealing at high temperatures (1000 °C or 1100 °C). High resolution transmission electron microscopy has been applied for investigation of the nanocrystals formation. Surface photovoltage spectroscopy technique was used for the spectral characterization of prepared structures

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Kim, Jaemin, Donghee Son, Mincheol Lee, Changyeong Song, Jun-Kyul Song, Ja Hoon Koo, Dong Jun Lee, et al. "A wearable multiplexed silicon nonvolatile memory array using nanocrystal charge confinement." Science Advances 2, no. 1 (January 2016): e1501101. http://dx.doi.org/10.1126/sciadv.1501101.

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Strategies for efficient charge confinement in nanocrystal floating gates to realize high-performance memory devices have been investigated intensively. However, few studies have reported nanoscale experimental validations of charge confinement in closely packed uniform nanocrystals and related device performance characterization. Furthermore, the system-level integration of the resulting devices with wearable silicon electronics has not yet been realized. We introduce a wearable, fully multiplexed silicon nonvolatile memory array with nanocrystal floating gates. The nanocrystal monolayer is assembled over a large area using the Langmuir-Blodgett method. Efficient particle-level charge confinement is verified with the modified atomic force microscopy technique. Uniform nanocrystal charge traps evidently improve the memory window margin and retention performance. Furthermore, the multiplexing of memory devices in conjunction with the amplification of sensor signals based on ultrathin silicon nanomembrane circuits in stretchable layouts enables wearable healthcare applications such as long-term data storage of monitored heart rates.

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Emelyanov E. A., Del’ T. A., Petrushkov M. O., Nastovjak A. G., Spirina A. A., Gavrilova T. A., Semyagin B. R., Vasev A. V., Putyato M. A., and Preobrazhenskii V. V. "Arrays of Quasi-One-Dimensional GaAs Nanocrystals Grown on the Oxidized Surface of the Si/GaAs(001) Heterostructure: Effect of the Si Epitaxial Layer on the Array Structure." Technical Physics Letters 49, no. 2 (2023): 26. http://dx.doi.org/10.21883/tpl.2023.02.55366.19334.

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Structures with arrays of planar and tilted quasi-one-dimensional GaAs nanocrystals have been grown on GaAs(001) substrates. An epitaxial silicon layer oxidized in air was used as a passivation coating. The amount of silicon deposited varied from structure to structure and was equivalent to 1, 2, 4, and 6 atomic layers. It has been found that in the case of a passivation layer based on silicon with a thickness of 1 atomic layer, an array of planar nanocrystals is formed, and in other cases, inclined quasi-one-dimensional nanocrystals. Nanocrystals are surrounded by crystallites, the shape, size, orientation, and distribution density of which change with the amount of silicon. The lowest density of crystallites was achieved with a silicon layer 6 atomic layers thick. Keywords: molecular-beam epitaxial, GaAs, Si, quasi-one-dimensional nanocrystals, vapour-liquid-crystal.

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31

Lee, Soo Jin, Woon Jo Cho, Chong Shik Chin, and Il Ki Han. "Sonochemical Synthesis of Silicon Nanocrystals." Key Engineering Materials 277-279 (January 2005): 995–99. http://dx.doi.org/10.4028/www.scientific.net/kem.277-279.995.

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Silicon nanocrystals in a range from 2 nm to 5 nm were prepared from Zintl salt, soldium silicide (NaSi) by sonochemical method. This synthesis permits that the reaction be completed in only a few hours and the easy alkyl-modification of nanocrystals surface at room temperature and ambient pressure. The average size of nanocrystals measured by the dynamic light scattering analysis was 2.7 nm. The high-resolution transmission electron micrograph confirmed the material identity of nanocrystals as crystalline silicon. FT-IR spectra are consistent with the surface states of nanocrystals that are chlorine-or butyl-capped. The emission peak center moved to a longer wavelength (up to 430 nm) with the reaction time, under a 325 nm excitation.

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32

Емельянов, Е. А., Т. А. Дель, М. О. Петрушков, А. Г. Настовьяк, А. А. Спирина, Т. А. Гаврилова, Б. Р. Семягин, А. В. Васев, М. А. Путято, and В. В. Преображенский. "Массивы квазиодномерных нанокристаллов GaAs, выращенные на окисленной поверхности гетероструктуры Si/GaAs(001): влияние толщины эпитаксиального слоя Si на строение массива." Письма в журнал технической физики 49, no. 3 (2023): 37. http://dx.doi.org/10.21883/pjtf.2023.03.54465.19334.

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Structures with arrays of planar and tilted quasi-one-dimensional GaAs nanocrystals have been grown on GaAs(001) substrates. An epitaxial silicon layer oxidized in air was used as a passivation coating. The amount of silicon deposited varied from structure to structure and was equivalent to 1, 2, 4, and 6 atomic layers. It has been found that in the case of a passivation layer based on silicon with a thickness of 1 atomic layer, an array of planar nanocrystals is formed, and in other cases, inclined quasi-one-dimensional nanocrystals. Nanocrystals are surrounded by crystallites, the shape, size, orientation, and distribution density of which change with the amount of silicon. The lowest density of crystallites was achieved with a silicon layer 6 atomic layers thick.

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33

Pavesi, L. "Silicon-Based Light Sources for Silicon Integrated Circuits." Advances in Optical Technologies 2008 (June 30, 2008): 1–12. http://dx.doi.org/10.1155/2008/416926.

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Silicon the material per excellence for electronics is not used for sourcing light due to the lack of efficient light emitters and lasers. In this review, after having introduced the basics on lasing, I will discuss the physical reasons why silicon is not a laser material and the approaches to make it lasing. I will start with bulk silicon, then I will discuss silicon nanocrystals and Er3+ coupled silicon nanocrystals where significant advances have been done in the past and can be expected in the near future. I will conclude with an optimistic note on silicon lasing.

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34

Nussupov, K. Kh, N. B. Beisenkhanov, S. A. Kukushkin, A. T. Sultanov, S. Keiinbay, D. S. Shynybayev, and A. Zh Kusainova. "FORMATION OF CRYSTALLINE SiC IN NEAR-SURFACE SILICON LAYERS BY METHOD OF COORDINATED SUBSTITUTION OF ATOMS." Herald of the Kazakh-British technical university 20, no. 2 (July 1, 2023): 27–35. http://dx.doi.org/10.55452/1998-6688-2023-20-2-27-35.

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In this work, monocrystalline films of silicon carbide were synthesized on the surface of a Si(100) silicon wafer using the method of coordinated substitution of atoms. The films were synthesized at temperatures of 1200 °C and 1300 °C for 20 minutes in a CO gas flow at a pressure of 0.8 Pa. The effect of 1200–1300 °C temperatures on the formation of single- and polycrystalline layers, as well as nanostructured SiC phases in the near-surface region of silicon by the method of atom substitution, is analyzed. The formation of a high-quality crystalline silicon carbide film and the influence of synthesis conditions on the total volume of SiC structural phases, microstructure and nanostructure of the surface are shown. It was found that an increase in temperature from 1200 °C to 1300 °C led to a more intensive formation of silicon carbide and an increase in the number of Si–C bonds by 1.9 times due to an increase in the thickness of the synthesized silicon carbide layer. There is an increase in the proportion of the crystalline phase due to a more intense transformation of the nuclei of nanocrystals into micro- and nanocrystals. Intense processes of penetration of carbon atoms deep into silicon at a temperature of 1300 °C with amorphization of its structure and the formation of Si-C, which can transform into crystalline phases at temperatures above 1300 °C, are assumed. The proportion of the SiC crystalline phase increases to 50.2% of the film volume due to the intensive transformation of nanocrystal nuclei into micro- and nanocrystals. It has been experimentally shown that the formation of various SiC structures on Si (100) occurs in full accordance with the main principles of the method of coordinated substitution of atoms.

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35

Marukovich, E. I., V. Yu Stetsenko, and A. V. Stetsenko. "Nanostructural crystallization of silumins." Litiyo i Metallurgiya (FOUNDRY PRODUCTION AND METALLURGY), no. 1 (March 12, 2022): 40–42. http://dx.doi.org/10.21122/1683-6065-2022-1-40-42.

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The crystallization of silumins has been shown to be a nanostructured process. Liquid silumin consists of elementary nanocrystals of aluminum and silicon, free atoms of aluminum and silicon, aluminum-silicon complexes. Primary microcrystals are formed from them. Eutectic microcrystals are formed from elementary nanocrystals of silicon and aluminum, aluminumsilicon complexes.

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36

Furuta, Kenta, Minoru Fujii, Hiroshi Sugimoto, and Kenji Imakita. "Energy Transfer in Silicon Nanocrystal Solids Made from All-Inorganic Colloidal Silicon Nanocrystals." Journal of Physical Chemistry Letters 6, no. 14 (July 2015): 2761–66. http://dx.doi.org/10.1021/acs.jpclett.5b01067.

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37

Kohno, Hideo, and Seiji Takeda. "Chain of Silicon Nanocrystals." Materia Japan 37, no. 12 (1998): 1017. http://dx.doi.org/10.2320/materia.37.1017.

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38

KANEMITSU, Yoshihiko. "Light-Emitting Silicon Nanocrystals." Nihon Kessho Gakkaishi 38, no. 2 (1996): 144–50. http://dx.doi.org/10.5940/jcrsj.38.144.

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39

Ossicini, S., E. Degoli, F. Iori, O. Pulci, G. Cantele, R. Magri, O. Bisi, F. Trani, and D. Ninno. "Doping in silicon nanocrystals." Surface Science 601, no. 13 (July 2007): 2724–29. http://dx.doi.org/10.1016/j.susc.2006.12.083.

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40

Arduca, Elisa, and Michele Perego. "Doping of silicon nanocrystals." Materials Science in Semiconductor Processing 62 (May 2017): 156–70. http://dx.doi.org/10.1016/j.mssp.2016.10.054.

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41

Heintz, Maggy. "Silicon nanocrystals to order." Materials Today 12, no. 4 (April 2009): 13. http://dx.doi.org/10.1016/s1369-7021(09)70108-7.

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42

Mariotti, Davide, Somak Mitra, and Vladimir Švrček. "Surface-engineered silicon nanocrystals." Nanoscale 5, no. 4 (2013): 1385. http://dx.doi.org/10.1039/c2nr33170e.

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43

Bruhn, Benjamin, Benjamin JM Brenny, Sidoeri Dekker, Ilker Doğan, Peter Schall, and Katerina Dohnalová. "Multi-chromatic silicon nanocrystals." Light: Science & Applications 6, no. 6 (February 10, 2017): e17007-e17007. http://dx.doi.org/10.1038/lsa.2017.7.

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44

Cornish, John C. L., Eman Mohamed, and Reem Abdelaal. "Engineering nanocrystals of silicon." Molecular Simulation 31, no. 6-7 (May 2005): 405–10. http://dx.doi.org/10.1080/08927020412331332695.

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45

Heitmann, J., F. Müller, M. Zacharias, and U. Gösele. "Silicon Nanocrystals: Size Matters." Advanced Materials 17, no. 7 (March 30, 2005): 795–803. http://dx.doi.org/10.1002/adma.200401126.

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46

Brus, Louis. "Luminescence of Silicon Nanocrystals and Porous Silicon." Japanese Journal of Applied Physics 34, S1 (January 1, 1995): 5. http://dx.doi.org/10.7567/jjaps.34s1.5.

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47

Ni, Zhenyi, Shu Zhou, Shuangyi Zhao, Wenbing Peng, Deren Yang, and Xiaodong Pi. "Silicon nanocrystals: unfading silicon materials for optoelectronics." Materials Science and Engineering: R: Reports 138 (October 2019): 85–117. http://dx.doi.org/10.1016/j.mser.2019.06.001.

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48

Kůsová, Kateřina, Prokop Hapala, Jan Valenta, Pavel Jelínek, Ondřej Cibulka, Lukáš Ondič, and Ivan Pelant. "Direct Bandgap Silicon: Tensile-Strained Silicon Nanocrystals." Advanced Materials Interfaces 1, no. 2 (December 19, 2013): 1300042. http://dx.doi.org/10.1002/admi.201300042.

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Pace, C., F. Crupi, D. Corso, and S. Lombardo. "Experimental Study of Single-Electron Phenomena in Silicon Nanocrystal Memories." Journal of Nanoscience and Nanotechnology 7, no. 1 (January 1, 2007): 322–28. http://dx.doi.org/10.1166/jnn.2007.18029.

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In this paper we present experimental evidence for single-electron phenomena in solid-state memories based on silicon nanocrystals as storage elements. The stepwise evolution of the channel current of a written memory cell biased in the subthreshold regime is monitored by means of a purposely designed low noise acquisition system with a bandwidth of 1 kHz. Each channel current step-up is ascribed to a single-electron emission from the silicon nanocrystal to the silicon substrate and each current step-down is ascribed to a single-electron capture from the silicon substrate into the silicon nanocrystal. The effect of the measurement system bandwidth on the detection of single-electron events is discussed and a procedure for extracting the threshold voltage shift associated to these events is proposed. It is shown that single-electron charging and discharging events in a memory cell with an area of 4.5 × 10−10 cm2 can cause threshold voltage shift at room-temperature of the order of several millivolts. Qualitative explanation for the observed threshold voltage shift distribution is given.

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Köthemann, Ronja, Christian Golla, Hong Qu, and Cedrik Meier. "Influence of Gold Nanoantennas on the Photoluminescence of Silicon Nanocrystals." Photonics 9, no. 12 (December 15, 2022): 985. http://dx.doi.org/10.3390/photonics9120985.

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We study the influence of gold nanoantennas on the photoluminescence signal of silicon nanocrystals. Unlike bulk silicon, which only exhibits low photoluminescence at room temperature due to its indirect band gap, silicon nanocrystals have the advantage of producing strong and size-dependent photoluminescence. Here, we place gold nanoantennas on a layered system in which silicon nanocrystals are integrated. The nanoantennas are embedded in the layered system by subsequent overgrowth. We find that the photoluminescence signal can be manipulated ranging from attenuation to enhancement. Moreover, we investigate the impact of grating coupling and the number of antennas per antenna array on the amplification of the photoluminescence signal.

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Journal articles on the topic 'Silicon nanocrystals'

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