The effect of defects and defects in gan semiconuctor:density functional theory (DFT) calculation

In this thesis, we predict the structural end electronic properties of GaN (zinc-blend) semi conductor including vacancy and impurity atoms by first principle density functinal theory (DFT) calculations. The band gap and density of state variation with concentrations of impurity and vacancy in GaN are performed using the CASTEP program package which is DFT code, operating in a plane- wave basis set in the simulations, the generalized gradient appraximation (GGA) is used with the excharge correlation potential by Perdew and Burke and Ernzerhof (PBE). The electron-ion interaction was considered in the ultrasoft pseudopotential. I was found that band gap modifications occur for vacancy, Mg and Ge impurity atoms. In the other hand, the bowing parameters which was determining the variations of band gap and lattice parameter for the Mg and Ge concentrations are estimated.