First Principles Study Of β-Si₃N₄ Materials

Density function theory is suitable for the multi-electron system by considering a single-electron system. The parameters such as binding energy,lattice constants,bulk modules calculated by density function theory of semiconductor and metal materials have shown to be in good agreement with the experimental results. As such, the first principles study of the condensed matter materials based on density function theory is being paid more and more attention. To date, a great deal of arithmetic based on density function theory, including LCAO-TB,OPW,PWP,LAPW and LMTO, etc., has been developed. With the development of the large,high-speed computers in recent years and report of a lot of experimental data, the first principles calculation has played a more and more important role in studying physical properties of materials and designing new types of materials.Silicon Nitride (Si3N4) has been widely applied in such fields as micro- electronics and optoelectronics as a promising ceramic material because of its excellent properties. Much work has been done to prepare silicon nitride by all kinds of CVD (Chemical Vapor Deposition). However, the electrical structure and optical properties of Si3N4 have not been investigated in detail by the first principles theory. On the other hand, to our knowledge, there are very few reports on the study of the C-doped Si3N4 to date.In this thesis, we calculated the electrical and optical properties ofβ- Si3N4 andβ- Si3N4: C by the first principles calculation based on PWP. The main research work is divided into two parts:...