Noise and its correlation to deep defects in Mg-doped GaN

We investigate p-type GaN: Mg materials using noise spectroscopy. The epitaxial Mg-doped GaN layers were grown on a sapphire substrate by metalorganic chemical vapour deposition. Significant generation-recombination noise is observed and shown to be linked to metastable DX-like centres. We correlate these centres with metastable defects with optical ionization energies 1.1 eV and 1.9eV, respectively, reported in previous work. The energy barriers for capture into and emission from the fundamental state are quantitatively determined. We propose a model for the configuration coordinate diagram that explains the persistent photoconductivity in GaN: Mg in the light of our results obtained from noise spectroscopy.