Origin of persistent photocurrent in GaN/AlGaN multiquantum wells

We performed systematic photocurrent experiments on GaN/AlGaN multiple quantum wells, both spectrally and temporally resolved. We show that a photopersistence effect is present in our samples even at room temperature. A comparison with photoluminescence (PL) results indicates that a yellow band-like feature is observable in photocurrent spectra which is not seen in PL, indicating the existence of defects which give rise to carrier trapping rather than recombination. A suitable interpretation of results is proposed.