Energy-bant calculation of AlxGa1-xN alloys

ENERGY-BANT CALCULATION OF AlxGa1-xN ALLOYS(M.Sc. Thesis)Ayten KAYAGAZI UNIVERSITYINSTITUTE OF SCIENCE AND TECHNOLOGYFebruary 2007ABSTRACTThe variation, related to Al concentration of the physical properties of zinc-blendeAlxGa1-xN were performed using CASTEP programme within the framework of densityfunction theory (DFT). The exchange-corelation energy of the electrons is described inthe GGA-PBE function with ultrasoft pseudopotential. The calculations show that, theconvenient cut-off energy is 330 eV for GaN and 280 eV for AlN. For 2x2x1 supercellAlxGa1-xN, the calculations were performed with 350 eV cut-off energy and produced theenergy-band gaps and the density of states (DOS) for each concentrations of Al. We notethat the bowing parameter which was determining the variation, related to Alconcentration of the energy-band gap is 0,1 for the direct band-gap and -0,04 for theindirect band-gap. The values of the bowing parameter which were performed withCASTEP are agreeable with the other calculation values.Science Code : 202.1.147Key Words : DFT, AlxGa1-xN, energy gapPage Number : 52: Prof. Dr. Bülent KUTLUAdviser