Evaluation of deep levels in GaN grown by RF-MBE on GaN template by capacitance DLTS

摘要

The dependence of deep levels in GaN epitaxial layer grown by molecular beam epitaxy on the V/III ratio was studied by capacitance deep level transient spectroscopy (DLTS). Four peaks corresponding to the electron traps were observed in the unintentionally n-doped GaN films grown at various growth conditions. The deep level concentrations of T1 (0.31 eV) and T4 (0.21 eV) traps increased with decrease of rnthe V/III ratio. This suggests that Tl and T4 traps are related to the N-vacaneies. Those of T2 (0.84 eV) and T3 (L,13 eV) traps did not show obvious dependence on the V/III ratio, but the concentration of the T2 and T3 traps - increased with increase of the residual carrier concentration. T2 and T3 traps might have some correlation with the residual donor. species.