Local vibrational modes as a probe of activation process in <i>p</i>-type GaN

Abstract

Raman spectra for a series of Mg-doped GaN films grown by metal organic chemical vapor deposition and annealed in N2 ambiance at different temperatures have been investigated. Some local vibrational modes related to hydrogen were observed, showing drastic changes with the annealing temperature. The spectra show clearly that H impurities incorporated in as-grown films, which passivate Mg acceptors, are released from the Mg–N bonding at above ∼600 °C, and diffuse in the film to form new chemical bondings. We have also observed a local mode related to activated Mg acceptors. This mode is conveniently used as a probe of the activation process of Mg acceptors.