Photoionization study of deep centers in GaN∕AlGaN multiple quantum wells

Transient photocapacitance (TPC) measurements were performed to investigate deep centers in GaN∕AlGaN multiple quantum wells. The influence of the persistent photovoltaic effect was successfully separated during the TPC experiments. The resolution obtained by the TPC measurements is much better than that of steady-state photocapacitance. The spectral dependence of photoionization cross section of deep centers in GaN is quantitatively determined in the energy range from 1.68to3.30eV. The absolute values of photoionization cross sections of these centers are found to be of the order of 10−15–10−14cm2.