Schottky barrier detectors on 4H-SiC n-type epitaxial layer for alpha particles

Abstract

Schottky barrier detectors have been fabricated on 50μm n-type 4H-SiC epitaxial layers grown on 360μm SiC substrates by depositing ∼10nm nickel contact. Current–voltage (I–V) and capacitance–voltage (C–V) measurements were carried out to investigate the Schottky barrier properties. The detectors were evaluated for alpha particle detection using a 241Am alpha source. An energy resolution of ∼2.7% was obtained with a reverse bias of 100V for 5.48MeV alpha particles. The measured charge collection efficiency (CCE) was seen to vary as a function of bias voltage following a minority carrier diffusion model. Using this model, a diffusion length of∼3.5μm for holes was numerically calculated from the CCE vs. bias voltage plot. Rise-time measurements of digitally recorded charge pulses for the 5.48MeV alpha particles showed a presence of two sets of events having different rise-times at a higher bias of 200V. A biparametric correlation scheme was successfully implemented for the first time to visualize the correlated pulse-height distribution of the events with different rise-times. Using the rise-time measurements and the biparametric plots, the observed variation of energy resolution with applied bias was explained.