Exciton quenching in Pt/GaN Schottky diodes with Ga- and N-face polarity

Abstract

We observed a peculiar dependence of low-temperature electroreflectance spectra of Pt/GaN Schottky diodes with Ga- and N-face polarity on the bias voltage (so-called “rotation” spectra), indicating the quenching of discrete exciton states and the formation of an exciton dead layer (EDL) beneath the gate. Data analysis is carried out using the field-dependent dielectric function of GaN. It yields parameters of excitons for the zero-field limit and the depth of the EDL, as well as the surface band bending and the ionized impurity concentration.