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Investigation on Structure of Element Semiconductor Material Si and Ge Melt

Author: WuJun
Tutor: LiuCaiChi
School: Hebei University of Technology
Course: Materials Physics and Chemistry
Keywords: High temperature X -ray diffraction Molecular dynamics simulation Melt structure Silicon Germanium
CLC: TN304.1
Type: Master's thesis
Year: 2010
Downloads: 66
Quote: 0
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Abstract


Elemental semiconductor silicon germanium materials, especially silicon material is important in today 's semiconductor industry microelectronic and optoelectronic materials , microstructure study the melt has an important guiding significance to control the crystal growth process , in addition, the liquid structure is cohesion an important branch of the state physics , this study is relatively backward , the research also has important theoretical value . In this paper, the high - temperature X-ray diffraction analysis of the structure of element semiconductor silicon materials near the melting point (1683K-1743K) , in combination with molecular dynamics simulations to supplement this data to draw the structure factor , pair distribution function and diameter relationship to the distribution function varies with temperature , the microscopic structure of the Si melt ; using both molecular dynamics simulations to study the microstructure of the element semiconductor Ge melt . Experimental measurements of the silicon melt is closer to their simulation results , the microstructure parameters are as follows: silicon melt nearest atomic distance 0.245nm first coordination surface coordination number is 6.5, and the the coherent radius of 0.92nm group the cluster average atomic number is 147 , structural parameters not change with the temperature near the melting point . The radial distribution function Gauss decomposition results show that the melt containing a covalent bond, the proportion of about 27 % . The first peak of the structure factor of three peaks fitting results show that the melt containing regular tetrahedron structure . The mean square displacement and velocity autocorrelation function of the calculated results show that the atoms in the melt at the melting temperature of the self-diffusion coefficients for the 6 × 10 - 4cm2 / s , as the temperature is increased further , the self-diffusion coefficient increased slightly . The VP analysis and bond angle distribution analysis showed that the melt ordered atomic clusters form a tetrahedral and simple cubic structure, a small number of atoms to form other complex disordered structure . The germanium melt molecular dynamics simulation results show that the : germanium melt nearest atomic distance of 0.26 nm , the first coordination surface with a median of 5.04, the the coherent radius of 0.82 nM , the average number of atoms of clusters of 103 months . Atoms melting temperature self-diffusion coefficient of 6.5 × 10-4cm2 / s, the structural parameters not change with the temperature near the melting point .

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CLC: > Industrial Technology > Radio electronics, telecommunications technology > Semiconductor technology > General issues > Material > Elemental semiconductors
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