X-ray and electron response of 4H-SiC vertical interdigitated Schottky photodiodes

Abstract

We report on the X-ray and electron performance of a low voltage reverse biased 4H-SiC vertical Schottky photodiode, based on the pinch-off surface effect, obtained by means of self-aligned Nickel Silicide (Ni2Si) interdigitated contacts. Although these photodiodes were original designed for UV detection their open Schottky contact is attractive for soft X-ray and low energy electron detection. The open electrode structure of the device allows the incident radiation to reach the active layer with minimal absorption. The photon counting spectroscopy response for soft X-rays is reported and compared to those predicted from a Monte Carlo model for SiC devices. We also show these devices can detect beta particles from 3H and 14C radioisotope sources with a combined energy range 1–156 keV.