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INVESTIGATION OF DEFECTS IN Ge-DOPED GaAs CRYSTAL GROWN IN A MAGNETIC FIELD

KANG JUN-YONG,HUANG QI-SHENG,

中国物理 B , 1995,
Abstract: Ge-doped GaAs single crystals have been grown by liquid-encapsulated Czochralski method in absence and presence of a magnetic field of 4000Gauss. By means of high op-tical efficiency photoluminescence, spectra of the grown crystals at room temperature were obtained, which consist of two emission bands A and B at 1.39-1.42eV and 0.97-1.05eV, respectively. Comparing the photoluminescence mappings with microphotographs of etched wafers, Hall effect results and electron probe microanalyses of the n- and p-type crystals with different Ge concentrations, we considered that the emission bands A and B originate from Ge-related acceptor and donor complexes, respectively. The complexes were formed during crystal growth, mainly due to temperature fluctuations in molten Ge-doped GaAs. The concentrations and homogeneities of the defects can be improved by the application of a magnetic field during crystal growth to suppress the temperature fluctuation.
UV-Photoinduced Defects In Ge-Doped Optical Fibers  [PDF]
F. Messina,M. Cannas,K. Medjahdi,A. Boukenter,Y. Ouerdane
Physics , 2005,
Abstract: We investigated the effect of continuous-wave (cw) UV laser radiation on single-mode Ge-doped H2- loaded optical fibers. An innovative technique was developed to measure the optical absorption (OA) induced in the samples by irradiation, and to study its dependence from laser fluence. The combined use of the electron spin resonance (ESR) technique allowed the structural identification of several radiation-induced point defects, among which the Ge(1) (GeO4 -) is found to be responsible of induced OA in the investigated spectral region.
Ge-vacancy complexes in Ge-doped czochralski silicon crystal
微锗掺杂直拉单晶硅中的锗-空位复合体

Wu Tai-Quan,
吴太权

物理学报 , 2012,
Abstract: The first-principls theory is used to study the interaction between the Ge atom and the vacancies in Ge-doped czochralski silicon. The CASTEP calculation shows the stable structural model of Ge atom and one vacancy, two vacancies and three vacancies through the distance between the Ge atom and vacancy (or the vacancy centers) and the size of the area (or volume). The calculation shows that the Ge atom introduced into the GCZ Si crystal tends to accumulate with the vacancy and then seeds for the Ge-vacancy complexes.
Flame Hydrolysis Deposition of Germanium Doped Silicaon Silicon Substrate
Si基片上掺Ge SiO_2的火焰水解法制备

Gao Dingshan,Li Jianguang,Wang Hongjie,An Junming,Li Jian,Xia Junlei,Hu Xiongwei,
郜定山
,李建光,王红杰,安俊明,李健,夏君磊,胡雄伟

半导体学报 , 2004,
Abstract: Germanium doped silica (GeO 2-SiO 2) soot is deposited on single crystal silicon substrate by flame hydrolysis deposition.Then this soot is consolidated to form glass in a high-temperature furnace.The surface morphologies of the samples are viewed by optic microscope,and the influence of different consolidating processes on the morphologies of the samples is studied.X-ray photoelectron spectroscopy is used to determine the elemental composition of the samples.The refractive indexes and thicknesses of the samples are measured by prism coupling method.All results show that the GeO 2-SiO 2 glass fabricated by appropriate process has smooth surface and tunable refractive index and thickness.This GeO 2-SiO 2 glass can be used as the core layer of silica-on-silicon waveguide components.
Capacitance-transient spectroscopy on irradiation-induced defects in Ge
Arne Nylandsted Larsen,Abdelmadjid Mesli
Optica Applicata , 2006,
Abstract: Recent studies of room-temperature irradiation-induced defects in Ge using space-charge capacitance-transient spectroscopy are reviewed. From these measurements only two defect complexes have been unambiguously identified until now: the E-center (the group-V impurity-vacancy pair) and the A-center (the interstitial oxygen-vacancy pair). However, contrary to silicon where each of these centers introduces only one energy level, in germanium the E-center has three energy levels corresponding to four charge states (=, –, 0, +), and the A-center has two levels corresponding to three charge states (=, –, 0). Another feature specific to each material is the anneal temperature. Both centers disappear below 150°C in germanium, whereas in silicon the E-center anneals out at ~150°C, depending on the charge state, and the A-center is stable up to 350°C.
Extended point defects in crystalline materials: Ge and Si  [PDF]
Nick E. B. Cowern,Sergei Simdyankin,Chihak Ahn,Nick S. Bennett,Jonathan P. Goss,Jean-Michel Hartmann,Ardechir Pakfar,Silke Hamm,Jér?me Valentin,Enrico Napolitani,Davide De Salvador,Elena Bruno,Salvatore Mirabella
Physics , 2012, DOI: 10.1103/PhysRevLett.110.155501
Abstract: B diffusion measurements are used to probe the basic nature of self-interstitial 'point' defects in Ge. We find two distinct self-interstitial forms - a simple one with low entropy and a complex one with entropy ~30 k at the migration saddle point. The latter dominates diffusion at high temperature. We propose that its structure is similar to that of an amorphous pocket - we name it a 'morph'. Computational modelling suggests that morphs exist in both self-interstitial and vacancy-like forms, and are crucial for diffusion and defect dynamics in Ge, Si and probably many other crystalline solids.
Defects of Ge quantum dot arrays on the Si(001) surface  [PDF]
V. A. Yuryev,L. V. Arapkina
Physics , 2009, DOI: 10.1016/j.physb.2009.08.118
Abstract: Defects of Ge quantum dot arrays may affect the electrophysical, photoelectrical or optical properties of Ge/Si heterostructures as well as the functionality of devices produced on their basis. The defects of Ge quantum dot arrays formed at moderate temperatures on the Si(001) surface have been investigated by the ultra high vacuum scanning tunnelling microscope integrated with the molecular beam epitaxy chamber. A preliminary classification of the defects has been carried out. Morphological peculiarities of the defects have been studied. The surface densities of defects of different types have been determined.
Vacancy complexes with oversized impurities in Si and Ge  [PDF]
H. Hoehler,N. Atodiresei,K. Schroeder,R. Zeller,P. H. Dederichs
Physics , 2004, DOI: 10.1103/PhysRevB.71.035212
Abstract: In this paper we examine the electronic and geometrical structure of impurity-vacancy complexes in Si and Ge. Already Watkins suggested that in Si the pairing of Sn with the vacancy produces a complex with the Sn-atom at the bond center and the vacancy split into two half vacancies on the neighboring sites. Within the framework of density-functional theory we use two complementary ab initio methods, the pseudopotential plane wave (PPW) method and the all-electron Kohn-Korringa-Rostoker (KKR) method, to investigate the structure of vacancy complexes with 11 different sp-impurities. For the case of Sn in Si, we confirm the split configuration and obtain good agreement with EPR data of Watkins. In general we find that all impurities of the 5sp and 6sp series in Si and Ge prefer the split-vacancy configuration, with an energy gain of 0.5 to 1 eV compared to the substitutional complex. On the other hand, impurities of the 3sp and 4sp series form a (slightly distorted) substitutional complex. Al impurities show an exception from this rule, forming a split complex in Si and a strongly distorted substitutional complex in Ge. We find a strong correlation of these data with the size of the isolated impurities, being defined via the lattice relaxations of the nearest neighbors.
Electronic and Magnetic Properties of Mn doped Ge Nanowires  [PDF]
J. T. Arantes,Ant?nio J. R. da Silva,A. Fazzio
Physics , 2006,
Abstract: Using {\it ab initio} total energy density-functional theory calculations, we investigate the electronic, structural and magnetic properties of Manganese doped Germanium nanowires. The nanowires have been constructed along the [110] direction and the dangling bonds on the surface have been saturated by hydrogen atoms. We observed that the Mn has lower formation energy at the center of the wire when compared to regions close to the surface. The Mn-Mn coupling has lower energy for a high-spin configuration except when they are first nearest neighbors. These results show that Ge:Mn nanowires are potential candidates for ferromagnetic quasi-one dimentional systems.
Impurity-vacancy complexes and ferromagnetism in doped sesquioxides  [PDF]
Paola Alippi,Maura Cesaria,Vincenzo Fiorentini
Physics , 2013, DOI: 10.1103/PhysRevB.89.134423
Abstract: Based on hybrid density-functional calculations, we propose that ferromagnetism in the prototypical bixbyite sesquioxide In$_2$O$_3$ doped with Cr is due to Cr-oxygen vacancy complexes, while isolated Cr cannot support carrier-mediated magnetic coupling. Our proposal is consistent with experimental facts such as the onset of ferromagnetism in O-lean conditions only, the low or vanishing net moment in unintentionally doped material, and its increase upon intentional doping.
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