Characterization of deep levels in n‐GaN by combined capacitance transient techniques

Deep centers in undoped n‐GaN grown by Hydride Vapor Phase Epitaxy were characterized by Deep Level Transient Spectroscopy (DLTS), revealing four known levels with activation energies in the range 0.17–0.94 eV. Deeper levels in the bandgap were observed by photocapacitance (PHCAP) experiments. A correspondence can be established for the dominant DLTS level observed both by thermal and optical experiments, exploiting the temperature as a key parameter in PHCAP measurements. The Franck–Condon shift dF–C for this level was estimated around 0.33 eV, in close agreement with results obtained by Hacke and coworkers in a more elaborate way. The tentative assignment of most levels is discussed on the basis of literature, pointing out unsettled origins for some of them. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)