Calculations within density functional theory on the basis of the local density approximation are carried out to study the properties of intrinsic point defects in aluminum antimonide. Special care is taken to address finite-size effects, band gap error, and symmetry reduction in the defect structures. The correction of the band gap is based on a set of GW calculations. The most important defects are identified to be the aluminum interstitial $Al_{i,Al}^{1+}$, the antimony antisites $Sb_{Al}^0$ and $Sb_{Al}^{1+}$, and the aluminum vacancy $V_{Al}^{3-}$. The intrinsic defect and charge carrier concentrations in the impurity-free material are calculated by self-consistently solving the charge neutrality equation. The impurity-free material is found to be n-type conducting at finite temperatures.
Photoluminescence and thermally stimulated luminescence of synthetic and natural (morion and smoky) $α$-quartz crystals doped with aluminum and alkali ions were studied. The photoluminescence spectrum is characterized with the main blue band around 400 nm (~ 3.1 eV). The corresponding luminescence center is based on a defect containing aluminum and alkali as compensators in natural and synthetic quartz crystals. Photoluminescence can be detected at high temperatures above 700 K. The thermal quenching activation energy is 0.15 eV and the frequency factor is 3 10$^7$ s$^{-1}$. In the samples wit…
Aluminum single crystals are tested using X-Ray Bragg diffraction, which may have applications in microscopy and electronics fabrication industry. Yet, their efficiency for x- ray beam diffraction depends on the accurate crystal orientation, the microstructure and imperfections. Moreover, the final sample that is formed from the as-grown crystal by cutting, grinding, polishing and chemical etching, introduces various surface defects that penetrate deep into the crystal affecting its natural structure. Defect penetration is attributed to the fact that ultra-pure aluminum single crystals are sof…
Modeling the microstructural evolution of metal and alloys, specifically under irradiation, is essential to predict the aging properties of materials. Many models are based on a transition rate matrix describing the jump frequencies of defects and involve a master equation governing the time evolution of a state probability vector. Here, we present non-stochastic numerical techniques to characterize the motion of individual defects migrating over long distances prior to recombining or being absorbed by another defect, resorting to the theory of absorbing Markov chains. These important events a…
Leibniz-Institut für Kristallzüchtung（莱布尼茨晶体生长研究所）
In this work, we study the absorption properties of AlN in the range of 1.5 - 5.5 eV, as well as the meta-stable change in absorption induced by ultraviolet (UV) irradiation (photochromism), and the restoration of the initial state under the action of irradiation of 2 - 4 eV or elevated temperatures. UV irradiation results in a decrease of the absorption coefficient from 110 cm$^{-1}$ to 55 cm$^{-1}$ at 4.7 eV while in the visible range the absorption coefficient increases from values below 5 cm$^{-1}$ to ~35 cm$^{-1}$. Measurements with two linear polarizations, parallel and perpendicular to …
Ion thruster is a revolution technology with potential applications in space mission but the thrusters operation lifetime is limited by the sputtering from thruster components. In this work, molecular dynamic simulations are performed to explore the dependence of deformation characteristics of an aluminum surface on incident angle and kinetic energy under low-energy xenon-ion impact. The fraction of non-12-coordinated atoms is used to quantitatively characterize the microstructural evolution and defect density levels. It is found that defect density level has a linear relation with incident en…
Electropolishing has found wide application as the final surface treatment of metal products in mechanical engineering and instrumentation, medicine and reflective concentrators for PV cells. It was found that electropolishing (EP) not only reduces the surface roughness and changes its appearance, but improves many operational characteristics as well, such as corrosion resistance, endurance, tensile strength, and many others, and also changes the physicochemical properties, for example, reflectivity, electromagnetic permeability and electronic emission of some ferro-magnetic metals. This fact …
Thermodynamic Phase Stability, Structural, Mechanical, Optoelectronic, and Thermoelectric Properties of the III-V Semiconductor AlSb for Energy Conversion Applications
S.U. Umarov Physical-Technical Institute of NAST（纳兹尔科学院苏·乌马尔物理技术研究所）；School of Optoelectronic Engineering & CQUPT-BUL Innovation Institute, Chongqing University of Posts and Telecommunications（重庆邮电大学光电工程学院与CQUPT-BUL创新学院）
Quantum Monte Carlo assessment of embedding for for strongly correlated defects: interplay between mean-field starting point and interactions
University of Illinois at Urbana-Champaign（伊利诺伊大学厄巴纳-香槟分校）；University of California, Santa Barbara（加州大学圣塔芭芭拉分校）；Flatiron Institute（平顿研究所）；Bielefeld University（比勒费尔德大学）；Stony Brook University（石溪大学）
