scholarly journals Low Temperature Growth of the Nanotextured Island and Solid 3C-SiC Layers on Si from Hydric Si, Ge and C Compounds

Crystals ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 491
Author(s):  
Lev K. Orlov ◽  
Vladimir I. Vdovin ◽  
Natalia L. Ivina ◽  
Eduard A. Steinman ◽  
Yurii N. Drozdov ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Surface Morphology ◽  
High Frequency ◽  
Strong Electric Field ◽  
Quantum Confinement Effect ◽  
Spectral Lines ◽  
Growth Stages ◽  
Two Dimensional ◽  
Conductivity Anisotropy ◽  
Electron Dispersion

Different growth stages and surface morphology of the epitaxial 3C-SiC/Si(100) structures were studied. Heterocompositions were grown in vacuum from hydric compounds at a lower temperature. The composition, surface morphology and crystal structure of the 3C-SiC films were tested using X-ray diffraction, second ion mass spectrometry, scanning ion and electron microscopy, photo- and cathode luminescence. It was demonstrated that the fine crystal structure of the 3C-SiC islands was formed by the close-packed nanometer-size grains and precipitated on the underlying solid carbonized Si layer. Luminescence spectral lines of the solid carbonized Si layer, separated island and solid textured 3C-SiC layer were shifted toward the high ultraviolet range. The spectra measured by different methods were compared and the nature of the revealed lines was considered. This article discusses a quantum confinement effect observation in the 3C-SiC nanostructures and a perspective for the use of nanotextured island 3C-SiC layers as a two-dimensional surface quantum superlattice for high-frequency applications. The conductivity anisotropy and current-voltage characteristics of the two-dimensional superlattices with a non-additive electron dispersion law in the presence of a strong electric field were studied theoretically. Main efforts were focused on a search of the mechanisms allowing realization of the high-frequency negative dynamical conductivity for the structures having a positive static differential conductivity.

Surface morphology of {100} faces ofL-arginine phosphate monohydrate single crystals investigated by atomic force microscopy

2005 ◽  
Vol 38 (4) ◽  
pp. 657-660 ◽  
Author(s):  
Y. L. Geng ◽  
D. Xu ◽  
X. Q. Wang ◽  
G. H. Zhang ◽  
G. W. Yu ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Atomic Force Microscopy ◽  
Surface Morphology ◽  
Single Crystals ◽  
Liquid Flow ◽  
Growth Conditions ◽  
Mother Solution ◽  
Two Dimensional ◽  
Force Microscopy ◽  
Atomic Force

Surface morphology of {100} faces of LAP crystals was investigated by atomic force microscopy (AFM). Both the steps and the two-dimensional nuclei elongate along thebdirection, which is determined by the crystal structure. Fluctuations in the growth conditions could result in the formation of protuberances on the step fronts. Tree-like growth belts are initially observed on LAP crystals. It is assumed that the formation is caused by uneven liquid flow of the mother solution.

ФОРМИРОВАНИЕ ПЕРЕХОДНОГО СЛОЯ ALN НА ТЕМПЛЕЙТАХ 3С-SIC/SI(111) МЕТОДОМ АММИАЧНОЙ МОЛЕКУЛЯРНО-ЛУЧЕВОЙ ЭПИТАКСИИ

2020 ◽  
Vol 96 (3s) ◽  
pp. 148-153
Author(s):  
С.Д. Федотов ◽  
А.В. Бабаев ◽  
В.Н. Стаценко ◽  
К.А. Царик ◽  
В.К. Неволин
Keyword(s):  
Crystal Structure ◽  
Growth Rate ◽  
Low Temperature ◽  
Surface Morphology ◽  
Single Crystal ◽  
Root Mean Square Roughness ◽  
Rate Variation ◽  
Mean Square ◽  
Nucleation Layer ◽  
Low Temperature Epitaxy

Представлены результаты изучения морфологии поверхности и структуры слоев AlN, сформированных аммиачной МЛЭ на темплейтах 3C-SiC/Si(111) on-axis- и 4° off-axis-разориентации. Опробован технологический режим низкотемпературной эпитаксии зародышевого слоя AlN на поверхности 3C-SiC(111). Среднеквадратичная шероховатость поверхности (5 х 5 мкм) слоев AlN толщиной 150 ± 50 нм составила 2,5-3,5 нм на темплейтах 3C-SiC/Si(111) on-axis и 3,3-3,5 нм на 4° off-axis. Показано уменьшение шероховатости смачивающего слоя AlN при изменении скорости роста. Получены монокристаллические слои AlN(0002) со значениями FWHM (ω-геометрия) 1,4-1,6°. The paper presents the surface morphology and crystal structure of AlN layers formed by ammonia MBE on 3C-SiC/Si(111) on-axis and 4° off-axis disorientation. It offers the technological approach of low-temperature epitaxy of the AlN nucleation layer on the 3C-SiC (111) surface. Root mean square roughness (5 х 5 |xm) of AlN layers with thickness of 150 ± 50 nm was 2,5-3,5 nm onto on-axis templates and 3.3-3.5 nm onto 4° off-axis. It appears that the RMS roughness of the AlN surface is changing with the growth rate variation. Single-crystal AlN(0002) layers with FWHM values (ω-geometry) of 1.4-1.6° have been obtained.

Despeckling of Sar Images Using Shrinkage of Two-Dimensional Discrete Orthonormal S-Transform

2020 ◽  
pp. 2150023
Author(s):  
Priya R. Kamath ◽  
Kedarnath Senapati ◽  
P. Jidesh
Keyword(s):  
High Frequency ◽  
Low Frequency ◽  
Relevant Information ◽  
Detection Algorithm ◽  
Two Dimensional ◽  
Sar Images ◽  
S Transform ◽  
Processing Step ◽  
Frequency Components ◽  
Shock Filter

Speckles are inherent to SAR. They hide and undermine several relevant information contained in the SAR images. In this paper, a despeckling algorithm using the shrinkage of two-dimensional discrete orthonormal S-transform (2D-DOST) coefficients in the transform domain along with shock filter is proposed. Also, an attempt has been made as a post-processing step to preserve the edges and other details while removing the speckle. The proposed strategy involves decomposing the SAR image into low and high-frequency components and processing them separately. A shock filter is used to smooth out the small variations in low-frequency components, and the high-frequency components are treated with a shrinkage of 2D-DOST coefficients. The edges, for enhancement, are detected using a ratio-based edge detection algorithm. The proposed method is tested, verified, and compared with some well-known models on C-band and X-band SAR images. A detailed experimental analysis is illustrated.

scholarly journals Rational Design and Simulation of Two-Dimensional Perovskite Photonic Crystal Absorption Layers Enabling Improved Light Absorption Efficiency for Solar Cells

Energies ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2460
Author(s):  
Jian Zou ◽  
Mengnan Liu ◽  
Shuyu Tan ◽  
Zhijie Bi ◽  
Yong Wan ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Solar Cells ◽  
Photonic Crystal ◽  
Incident Light ◽  
Absorption Efficiency ◽  
Utilization Efficiency ◽  
Photonic Crystal Structure ◽  
Two Dimensional ◽  
Photoelectric Conversion ◽  
Absorption Layer

A two-dimensional perovskite photonic crystal structure of Methylamine lead iodide (CH3NH3PbI3, MAPbI3) is rationally designed as the absorption layer for solar cells. The photonic crystal (PC) structure possesses the distinct “slow light” and band gap effect, leading to the increased absorption efficiency of the absorption layer, and thus the increased photoelectric conversion efficiency of the battery. Simulation results indicate that the best absorption efficiency can be achieved when the scattering element of indium arsenide (InAs) cylinder is arranged in the absorption layer in the form of tetragonal lattice with the height of 0.6 μm, the diameter of 0.24 μm, and the lattice constant of 0.4 μm. In the wide wavelength range of 400–1200 nm, the absorption efficiency can be reached up to 82.5%, which is 70.1% higher than that of the absorption layer without the photonic crystal structure. In addition, the absorption layer with photonic crystal structure has good adaptability to the incident light angle, presenting the stable absorption efficiency of 80% in the wide incident range of 0–80°. The results demonstrate that the absorption layer with photonic crystal structure can realize the wide spectrum, wide angle, and high absorption of incident light, resulting in the increased utilization efficiency of solar energy.

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