Frist Principles Study For Electronic Structure And Dynamic Properties Of Wurtzite BN,AlN,GaN And InN

In the last few years, the group Ⅲ-nitrides semiconductor compounds GaN, AlN, BN and InN have attracted considerable attention, the distinguishing feature with respect to other conventional Ⅲ-Ⅴ group semiconductor (such as GaAs, AlAs, InAs), for nitrogen to form rather short bonds with B, Al, Ga or In. Consequently, BN, AlN, GaN and InN have a considerable hardness, high melting pint, high thermal conductivity and direct energy gap which span a substantial range from the visible to the ultraviolet region of the spectrum. As a result, They attracted increased attention on scientific researsh and technological applications. Ⅲ-N compounds have been widely used for electronic devices for high power, high-frequency operation, light emitting diodes, laser diode and optical detector. In this present paper, based on the density-function theory and density function perturbation theory, we report the calculation of structure, energy band and density of states with first-principles. Furthermore, we have calculated the dynamics properties of AlN, GaN, BN, InN with two different exchange-correlation functional in wurtzite structure and obtained relative suitable exchange-correlation energy for each compound.The results showed that AIN, GaN and InN belong to direct band gap semiconductor while BN falls into indirect one. And we also obtained the contribution of different electronic states of the different atoms and energy band for each material. From the phonon dispersion curves of different exchange-correlation, we found that exchange-correlation energy in the materials could affect the phonon frequency, the impact of InN, BN is greater than GaN and AIN, especially for InN,the differences of the largest optical modes up to100cm-1. Compared with other theoretical and experimental values, we found that the frequencies calculated with GGA are lower than the results with LDA, especially for InN. For AIN and GaN, LDA is more suitable, but for BN and InN, it is GGA. The calculation of relative splitting indicated AIN had the highest value, So the scale of phonon dispersion is obvious. Furthermore, AIN is more anisotropic than BN, GaN and InN.