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Minority Carrier Lifetime in As-Grown Germanium Doped Czochralski Silicon
ZHU Xin,YANG De-Ren,LI Ming,CHEN Tao,WANG Lei,QUE Duan-Lin,

中国物理快报 , 2008,
Abstract: The minority carrier lifetime of as-grown germanium-doped Czochralski (GCZ) silicon wafers doped with germanium concentrations Ge]=1016--1018cm-3 isinvestigated in comparison with conventional CZ silicon samples. It is found that the lifetime distribution along the ingot changes with the variation of Ge]. There is a critical value of Ge] = 1016cm-3 beyond which Ge can obviously influence the lifetime of as-grown ingots. This phenomenon is considered to be associated with the competition or combination between the oxygen related thermal donors (TDs) and electrically active Ge-relatedcomplexes. The related formation mechanisms and distributions are also discussed.
Influence of high pressure annealing on electrical properties of surface layer of neutron irradiated or germanium-doped Czochralski-grown silicon  [PDF]
Wojciech JUNG,Andrzej MISIUK,Charalambos A. LONDOS,Deren YANG
Optica Applicata , 2005,
Abstract: The effect of annealing at 720–920 K under enhanced pressure (up to 1.1 GPa) in argon ambient on electrical properties of the surface layer of the Czochralski-grown silicon (Cz-Si) subjected to neutron irradiation (doses of up to 1×1017 cm–2, E = 5 MeV) or germanium doping (doping level 7×1017 cm–3) was investigated by electrical C-V, I-V and admittance method. The stress-induced decrease in electron concentration was observed in both p- and n-type samples after neutron irradiation and annealing under a pressure of 1.1 GPa at 720 K for 10 hours, while in the germanium doped samples an ascending dependence of the creation of thermal donors and lack of dependence of new donors on hydrostatic pressure was observed. The effects observed can be explained as resulting, among others, from the irradiation-induced defects (generation of thermal acceptors) and pressure stimulated creation of thermal donors in germanium-doped silicon.
TEM and STEM Observations of a Flat Continuous Silicon-Germanium Thin Film Epitaxially Grown on Porous Silicon  [PDF]
Junji Yamanaka, Noritaka Usami, Sevak Amtablian, Alain Fave, Mustapha Lemiti, Chiaya Yamamoto, Kiyokazu Nakagawa
Journal of Materials Science and Chemical Engineering (MSCE) , 2017, DOI: 10.4236/msce.2017.51004
Strain-relaxed SiGe is an attractive material for use as a substrate of strained Si, in which carrier mobility is higher than that of bulk Si. The concept of this study is the use of porous Si as a sponge like substrate so that a SiGe lattice can relax without introducing dislocations. We produced porous Si specimens by electrochemical anodization and annealed them under a H2 atmosphere. Then, SiGe thin films were grown by gas-source molecular beam epitaxy. We observed the microstructure of the specimens using transmission electron microscopy. The result showed that we succeeded in producing a single-crys- tal continuous Si0.73Ge0.27 film with a 10% relaxation ratio and a low dislocation density on porous Si.
UHV/CVD Grown Strain Relaxed SiGe Buffer Layers for Strained Silicon

Wu Guibin,Ye Zhizhen,Liu Guojun,Zhao Binghui,Cui Jifeng,

半导体学报 , 2005,
Abstract: Multi SiGe/Si layers with increasing Ge content are grown using ultra high vacuum chemical vapor deposition.Relaxation and Ge content are investigated with high resolution X-ray diffraction,SIMS,and AFM.By adopting this structure the Ge contents are remarkably improved,and a thin strain-relaxed SiGe buffer layer with high quality,low dislocation density,and smooth morphology is realized.The density of dislocations is calculated to be 1e6cm-2 through optical microscopy.
Spin dephasing in Silicon Germanium nanowires  [PDF]
Ashish Kumar,Bahniman Ghosh
Physics , 2011, DOI: 10.1063/1.3666022
Abstract: We study spin polarized transport in silicon germanium nanowires using a semiclassical monte carlo approach. Spin depolarization in the channel is caused due to D'yakonov-Perel (DP) relaxation associated with Rashba spin orbit coupling and due to Elliott- Yafet (EY) relaxation. We investigate the dependence of spin dephasing on germanium mole fraction in silicon germanium nanowires. The spin dephasing lengths decrease with an increase in the germanium mole fraction. We also find that the temperature has a strong influence on the dephasing rate and spin relaxation lengths increase with decrease in temperature. The ensemble averaged spin components and the steady state distribution of spin components vary with initial polarization.
Germanium Nanocrystals Embedded in Silicon Dioxide for Floating Gate Memory Devices  [PDF]
A. Bag,R. Aluguri,S.K. Ray
Journal of Nano- and Electronic Physics , 2011,
Abstract: Metal-oxide-semiconductor (MOS) capacitors with tri-layer structure consisting of rf magnetron sputtered grown germanium (Ge) nanocrystals (NCs) and silicon dioxide (SiO2) layers sandwiched between thermally grown tunnel and sputtered grown cap oxide layers of SiO2 were fabricated on p-Si substrates. Plane view transmission electron micrographs revealed the formation of spherically shaped and uniformly distributed Ge NCs. The optical and electronic characteristics of tri-layer structures were studied through photoluminescence (PL) spectroscopy and capacitance-voltage (C-V) measurements, respectively. Frequency dependent electrical properties of the structures have been studied. The optical emission characteristics support the confinement of the carriers in Ge NCs embedded in oxide matrices. An anticlockwise hysteresis in C-V characteristics suggests electron injection and trapping in Ge NCs.
Theory of interstitial oxygen in silicon and germanium  [PDF]
Emilio Artacho,Felix Yndurain
Physics , 1995,
Abstract: The interstitial oxygen centers in silicon and germanium are reconsidered and compared in an analysis based on the first-principles total-energy determination of the potential-energy surface of the centers, and a calculation of their respective low energy excitations and infrared absorption spectra. The total-energy calculations reveal unambiguously that interstitial oxygen is quantum delocalized, the delocalization being essentially different in silicon and in germanium. Oxygen in silicon lies at the bond center site in a highly anharmonic potential well, whereas in germanium it is found to rotate almost freely around the original Ge-Ge bond it breaks. This different delocalization is the origin of the important differences in the low energy excitation spectra: there is a clear decoupling in rotation and vibration excitations in germanium, giving different energy scales (1 cm$^{-1}$ for the rotation, 200 cm$^{-1}$ for the $\nu_2$ mode), whereas both motions are non-trivially mixed in silicon, in a common energy scale of around 30 cm$^{-1}$. The calculation of the vibrational spectra of the defect reveals the existence of vibrational modes (related to the $\nu_1$ mode) never been experimentally observed due to their weak infrared activity. It is found that the combination of these modes with the well established $\nu_3$ asymmetric stretching ones is the origin of the experimentally well characterized modes at frequencies above the $\nu_3$ mode frequency.
Energy landscape of relaxed amorphous silicon  [PDF]
Francis Valiquette,Normand Mousseau
Physics , 2003, DOI: 10.1103/PhysRevB.68.125209
Abstract: We analyze the structure of the energy landscape of a well-relaxed 1000-atom model of amorphous silicon using the activation-relaxation technique (ART nouveau). Generating more than 40,000 events starting from a single minimum, we find that activated mechanisms are local in nature, that they are distributed uniformly throughout the model and that the activation energy is limited by the cost of breaking one bond, independently of the complexity of the mechanism. The overall shape of the activation-energy-barrier distribution is also insensitive to the exact details of the configuration, indicating that well-relaxed configurations see essentially the same environment. These results underscore the localized nature of relaxation in this material.
Germanium crystals on silicon show their light  [PDF]
F. Pezzoli,F. Isa,G. Isella,C. V. Falub,T. Kreiliger,M. Salvalaglio,R. Bergamaschini,E. Grilli,M. Guzzi,H. von Kaenel,Leo Miglio
Physics , 2013,
Abstract: Germanium and silicon-germanium alloys have found entry into Si technology thanks to their compatibility with Si processing and their ability to tailor electronic properties by strain and band-gap engineering. Germanium's potential to extend Si functionalities, as exemplified by lasing action of strained-Ge on Si substrates, has brought the material back to attention. Yet despite these advances, non-radiative transitions, induced by crystal defects originating from the Ge/Si interface, continue to be a serious bottleneck. Here we demonstrate the drastic emission enhancement achieved via control and mitigation over the parasitic activity of defects in micronscale Ge/Si crystals. We unravel how defects affect interband luminescence and minimize their influence by controlling carrier diffusion with band-gap-engineered reflectors. We finally extended this approach designing efficient quantum well emitters. Our results pave the way for the large-scale implementation of advanced electronic and photonic structures unaffected by the ubiquitous presence of defects developed at epitaxial interfaces.

Ji Zhen-guo,Norikata Usami,H Sunamura,Yasuhiro Shiraki,

中国物理 B , 1998,
Abstract: Pure Ge/Si short period superlattice (SPS) samples grown by gas source molecular beam epitaxy (GS-MBE) were studied by photoluminescence and Raman scattering. For SPS samples with Germanium layer thickness (LGe) of 1.5 monolayer (ML), a new band of photoluminescence is observed for silicon layer thickness (LSi) in an intermediate range of 1.9-2.9 nm. In contrast to pure Ge/Si quantum wells, the energy of the new band shows a red-shift with the increase of LSi. Raman scattering results show that when the intensity of the photoluminescence of the new band reaches a maximum, the Raman shift relating the vibration of Si-Si reaches a minimum. It is therefore considered that the new band of the pure Ge/Si SPS is related with some kind of strain relaxation process.
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