Photoluminescence studies of GaN films of different buffer layer and doping concentration

Abstract

Photoluminescence (PL) measurements of GaN films with various buffer thicknesses and Si-doping concentrations have been carried out. PL response of one specific sample was studied for temperature dependence. The results showed that the band gap energy reduction is linearly proportional to the temperature increase with a slope of similar to-4 x 10(-4) eV.K-1 and that the activation energies for donor-bound and acceptor-bound exciton transitions are 15 and 18 meV, respectively. In Si-doped GaN films, the PL data indicated that the reduced gap depends on the third power of carrier concentration as n(1/3). We also obtained a concentration coefficient of 2.34 x 10(-4) eV.cm and a band gap energy of 3.426 eV in the undoped GaN film.