The Stability, Electronic Structure And Optical Property Of The New Spinel Nitride γ-GeSi₂N₄

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.Nowadays, based on density function theory, a great deal of arithmetic, including LCAO-TB,OPW,PWP,LAPW and LMTO, etc., have been developed. 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.Because of the excellent properties of IV-nitrides, they are considered to be promising ceramic materials, and to be applied in micro-electronics and photo-electronics field wildly. But many works can't be done on the recent experimental condition and only resort to the first principle research and simulation. But there is seldom first principle research about IV-nitrides, especially binary con-column cation nitrides.In this thesis, we have calculated the stability,electronic structure and optical properties of γ-GeSi₂N₄ based on the density function theory, and have compared with the properties of another three nitridesγ-GeSi₃N₄,γ-Ge₃N₄,γ-SiGe₂N₄. The total energy calculation demonstrates thatγ-GeSi₂N₄ is stable structure butγ-SiGe₂N₄ is unstable structure. We also have calculated the equation of state (EOS), bulk modulus, share modulus and elastic constants and compared them with other calculation. The results further confirmed the conclusion.Based on the study of the electronic structure of four nitrides, we have gotten the band structure,density of state (DOS). For the optical properties, we have calculated the dielectric function and refraction which can be used to describe the micro-electron structure of solid-state and the proceeding of photon transition in the semiconductor. The relation between main features on the optical function curves and band structure can be understood on the base of the Law of Conservation of Energy and the Law of Conservation of Momentum.