The First Principle Investigation On Structure And Effect Of Property Of β-SiC By N-Doping

Based on the Local Density Function Theory, the multi-electron problem can be converted to resolve the single-electron equation. For semiconductors and metal materials, the parameters such as binding energy, lattice constants, bulk modules which are calculated by density function theory have shown to be in good agreement with the experimental results. So the first principle study of the condensed matter materials has gotten a great achievement and been paid more and more attention. With the development of the large,high-speed computers' application in recent years;the first principle calculation has played a more and more important role in studying physical properties of materials and designing new types of materials.A computational design of the semiconductor materials with specific functional has became an important research field in computational materials science. Owing to the properties of the semiconductor depended on the electronic states and the current carrier distribution at valence band top and conduction band bottom, therefore the band-gap values and the symmetry of the band extremes are the most attention problems in materials design.The properties of nitrogen-dopedβ-SiC have been investigated by firstprin ciples calculations based on density functional theory. It is observed that the band-gap ofβ-SiC transforms from indirect band gap to direct band gap because of nitrogen impurity. It is attributed to the asymmetry reduction caused by defects of nitrogen-dopedβ-SiC that leads to the first brillouin zone narrowed,and brillouin zone folded.The quasi-free electron caused by nitrogen excite the outer-shell electron of Si,which make that conduction band is at the center of Brillouin Zone.And the properties of different doped concentrations have been be calculated. The results show that the width of forbidden band, depth of Fermi energy entering the conduction band, absorption coefficient and dielectric function are changed with the varieties of doping concentration.Excessive concentration still make crystal present the character of direct band structure. Therefore,the best performance materias need proper concentration.