Conductance Frequency Spectroscopy Study of a Low Resistive p-Type GaN Layer Highly Doped with Mg

A low resistive p-type GaN layer highly doped with Mg (1020 cm-3) was studied by conductance frequency spectroscopy. Three peaks were found in the G/f–f curve of the reversed-biased Mg doped p–n junction at temperatures ranging from 300 K to 77 K. The activation energies associated with two peaks are 63 meV and 90 meV, respectively around room temperatures, and decrease with decreasing temperatures. The activation energy of one more peak appearing at low temperatures is 16 meV, the value of which is very shallow compared to the reported value. Analysis using a multi-deep level model is given, and the experimental results are well explained by this analysis. These results suggest that the Mg acceptor in GaN has not a simple hydrogen-like structure, but a complex multi-level structure.