Analysis of non-exponential thermal emission transients in undoped MOCVD-grown GaN

Capacitance deep level transient spectroscopy (DLTS) has been used to characterise undoped GaN epitaxial layers grown by metal-organic chemical vapour deposition (MOCVD) on sapphire substrates. The DLTS measurements were performed by recording full capacitance transients over the 90 to 475 K temperature range. Nonexponential emission transients were observed in the samples studied. Modelling shows that these results can be adequately described by a set of traps with a Gaussian distribution of activation energies.