High-performance near-ultraviolet avalanche photodetectors based on ZnSe

Abstract

This We report on high-responsivity, fast nearultraviolet avalanche photodetectors based on bulk ZnSe employing a metal-semiconductor-metal structure. A very high responsivity of 2.42 A/W and 4.44 A/W at 20 V bias voltage for light with a wavelength of 325 nm was obtained for photodetectors without and with interdigital contacts, which indicates an internal gain. The mechanism of internal gain is attributed to the avalanche effect in ZnSe under high internal electric field. Also a low dark current of ~ 3.4 nA and high detectivity of ~ 1.4 × 1011 cm Hz1/2 W-1 at a voltage of 20 V was achieved for the device with interdigital contacts at room temperature.