Investigation On Structure Of Element Semiconductor Material Si And Ge Melt

Semiconductor material silicon and germanium is the very important material for micro-electronics and photoelectron in semiconductor industry nowadays, especially the silicon. Furthermore, the study of liquid structure is one important part of the condensed matter physics domain. The research has a very important theoretical value for this branch was standing on a lower position relatively.The high temperature X-ray diffraction instrument was used to analysis the structure of Semiconductor material Si at melting point(1683K-1743K) around, and the Molecular Dynamics simulation was used to complement the data, to figure out it's structure factor,pair correlation function and radial distributing function changes with temperature, and the microstructure of molten Si was discussed. The Molecular Dynamics simulation was also used to investigate the structure of Semiconductor material GeThe result of experiment and simulation indicated that the nearest neighbor distance for molten silicon is 0.245nm,the coordination numbers under first coordination sphere is 6.5,the radius of clusters is 0.92nm,the average atom amount of clusters is 147. The structure parameter changed a little with the increasing of temperature. The Gauss analyze of the RDF indicate that there have covalent bond in the melt, which has the proportion of 27%. The Lorentzian fit was used to fitting the first peak of structure factor, which indicate that there have a"shoulder"at the higher Q side and a beforehand peak at the lower Q side, which have respect with the contribution by second neighbor atoms and the inheritance of crystal structure. The mean square displacement and the velocity auto-correlation function of molten silicon was calculated, which indicated that the atoms already has a good diffusivity ability just at the very beginning of melting point, and this ability became stronger with increasing of temperature. It indicated that there has the tetrahedron and simple cube in the molten system mostly by the Voronoi polyhedron method, include other complex structure.The result of MD simulation for molten germanium indicate that the nearest neighbor distance is 0.26nm,the coordination numbers under first coordination sphere is 5.04,the radius of clusters is 0.82nm,the average atom amount of clusters is 103,the self-diffusion coefficient is 6.5×10-4cm2/s at melting point. The structure parameter changed a little with the increasing of temperature.