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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.
Feasibility of using thin crystalline silicon films epitaxially grown at 165 °C in solar cells: A computer simulation study  [cached]
Chakraborty S.,Cariou R.,Labrune M.,Roca i Cabarrocas P.
EPJ Photovoltaics , 2013, DOI: 10.1051/epjpv/2013014
Abstract: We have previously reported on the successful deposition of heterojunction solar cells whose thin intrinsic crystalline absorber layer is grown using the standard radio frequency plasma enhanced chemical vapour deposition process at 165 °C on highly doped P-type (100) crystalline silicon substrates. The structure had an N-doped hydrogenated amorphous silicon emitter deposited on top of the intrinsic epitaxial silicon layer. However to form the basis of a solar cell, the epitaxial silicon film must be chiefly responsible for the photo-generated current of the structure and not the underlying crystalline silicon substrate. In this article we use detailed electrical-optical modelling to calculate the minimum thickness of the epitaxial silicon layer for this to happen. We have also investigated by modelling the influence of the a-Si:H/epitaxial-Si and epitaxial-Si/c-Si interface defects, the thickness of the epitaxial silicon layer and its volume defect density on cell performance. Finally by varying the input parameters and considering various light-trapping schemes, we show that it is possible to attain a conversion efficiency in excess of 13% using only a 5 micron thick epitaxial silicon layer.
Silicon Layer Intercalation of Centimeter-Scale, Epitaxially-Grown Monolayer Graphene on Ru(0001)  [PDF]
Jinhai Mao,Li Huang,Yi Pan,Min Gao,Junfeng He,Haitao Zhou,Haiming Guo,Yuan Tian,Qiang Zou,Lizhi Zhang,Haigang Zhang,Yeliang Wang,Shixuan Du,Xingjiang Zhou,A. H. Castro Neto,Hong-Jun Gao
Physics , 2011, DOI: 10.1063/1.3687190
Abstract: We develop a strategy for graphene growth on Ru(0001) followed by silicon-layer intercalation that not only weakens the interaction of graphene with the metal substrate but also retains its superlative properties. This G/Si/Ru architecture, produced by silicon-layer intercalation approach (SIA), was characterized by scanning tunneling microscopy/spectroscopy and angle resolved electron photoemission spectroscopy. These experiments show high structural and electronic qualities of this new composite. The SIA allows for an atomic control of the distance between the graphene and the metal substrate that can be used as a top gate. Our results show potential for the next generation of graphene-based materials with tailored properties.
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.
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.
TEM Characterization of Defects in GaN/InGaN Multi-Quantum Wells Grown on Silicon by MOCVD

Zhu Hu,Li Cuiyun,Mo Chunlan,Jiang Fengyi,Zhang Meng,

半导体学报 , 2008,
Abstract: Transmission electron microscope(TEM)measurements performed on InGaN/GaN multiple-quantum-well(MQW)deposited Silicon substrates have been investigated.By taking high-resolution transmission electron microscopy(HRTEM)imagery,electron diffraction contrast imagery,and electron diffraction image in precincts between the Si substrate and the AlN buffer area,and also taking Two-beam electron diffract contrast imagery around the quantum well area,we have researched the characteristics of dislocation.In addition,we...
Effects of quantum statistics of phonons on the thermal conductivity of silicon and germanium nanoribbons
Yuriy A Kosevich,, Alexander V Savin and Andrés Cantarero
Nanoscale Research Letters , 2013, DOI: 10.1186/1556-276X-8-7
Abstract: We present molecular dynamics simulation of phonon thermal conductivity of semiconductor nanoribbons with an account for phonon quantum statistics. In our semiquantum molecular dynamics simulation, dynamics of the system is described with the use of classical Newtonian equations of motion where the effect of phonon quantum statistics is introduced through random Langevin-like forces with a specific power spectral density (color noise). The color noise describes interaction of the molecular system with the thermostat. The thermal transport of silicon and germanium nanoribbons with atomically smooth (perfect) and rough (porous) edges are studied. We show that the existence of rough (porous) edges and the quantum statistics of phonon change drastically the low-temperature thermal conductivity of the nanoribbon in comparison with that of the perfect nanoribbon with atomically smooth edges and classical phonon dynamics and statistics. The rough-edge phonon scattering and weak anharmonicity of the considered lattice produce a weakly pronounced maximum of thermal conductivity of the nanoribbon at low temperature.
Epitaxial growth of silicon and germanium on (100)-oriented crystalline substrates by RF PECVD at 175 °C  [cached]
Labrune M.,Bril X.,Patriarche G.,Largeau L.
EPJ Photovoltaics , 2012, DOI: 10.1051/epjpv/2012010
Abstract: We report on the epitaxial growth of crystalline Si and Ge thin films by standard radio frequency plasma enhanced chemical vapor deposition at 175 °C on (100)-oriented silicon substrates. We also demonstrate the epitaxial growth of silicon films on epitaxially grown germanium layers so that multilayer samples sustaining epitaxy could be produced. We used spectroscopic ellipsometry, Raman spectroscopy, transmission electron microscopy and X-ray diffraction to characterize the structure of the films (amorphous, crystalline). These techniques were found to provide consistent results and provided information on the crystallinity and constraints in such lattice-mismatched structures. These results open the way to multiple quantum-well structures, which have been so far limited to few techniques such as Molecular Beam Epitaxy or MetalOrganic Chemical Vapor Deposition.
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.
Crystallization of Electrodeposited Germanium Thin Film on Silicon (100)  [PDF]
Mastura Shafinaz Zainal Abidin,Ryo Matsumura,Mohammad Anisuzzaman,Jong-Hyeok Park,Shunpei Muta,Mohamad Rusop Mahmood,Taizoh Sadoh,Abdul Manaf Hashim
Materials , 2013, DOI: 10.3390/ma6115047
Abstract: We report the crystallization of electrodeposited germanium (Ge) thin films on n-silicon (Si) (100) by rapid melting process. The electrodeposition was carried out in germanium (IV) chloride: propylene glycol (GeCl 4:C 3H 8O 2) electrolyte with constant current of 50 mA for 30 min. The measured Raman spectra and electron backscattering diffraction (EBSD) images show that the as-deposited Ge thin film was amorphous. The crystallization of deposited Ge was achieved by rapid thermal annealing (RTA) at 980 °C for 1 s. The EBSD images confirm that the orientations of the annealed Ge are similar to that of the Si substrate. The highly intense peak of Raman spectra at 300 cm ?1 corresponding to Ge-Ge vibration mode was observed, indicating good crystal quality of Ge. An additional sub peak near to 390 cm ?1 corresponding to the Si-Ge vibration mode was also observed, indicating the Ge-Si mixing at Ge/Si interface. Auger electron spectroscopy (AES) reveals that the intermixing depth was around 60 nm. The calculated Si fraction from Raman spectra was found to be in good agreement with the value estimated from Ge-Si equilibrium phase diagram. The proposed technique is expected to be an effective way to crystallize Ge films for various device applications as well as to create strain at the Ge-Si interface for enhancement of mobility.
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