Conduction band discontinuity and carrier multiplication at the MgxZn1−xO/MgyZn1−yO interface

Abstract

Carrier multiplication is one process for improving the performance of deep ultraviolet (DUV) photodetectors. Conduction band discontinuity can make electrons obtain additional kinetic energy by potential energy (equal to ΔE_C) reducing, and then have sufficient energy to impact a lattice generating electron–hole pairs to increase the internal photocurrent. An active layer consisting of four-period graded bandgap MgZnO with a steep Mg_xZn_1−xO/Mg_yZn_1−yO heterointerface, in which an impact ionization process takes place, has been demonstrated. The fabricated photodetector shows a DUV detection capability with a cutoff wavelength at ∼280 nm. The peak responsivity at about 250 nm nonlinearly increases with the applied reverse bias.