Experimental analysis of the electric field distribution in semi-insulating GaAs detectors via alpha particles

Abstract

Semi-insulating gallium arsenide (SI GaAs) detectors offer a promising alternative to commercially available silicon detectors. They demonstrate superior radiation hardness and provide improved efficiency for gamma and X-ray detection, primarily attributed to their higher density. In this study, we examined 350 μm thick SI GaAs detectors featuring front-side Ti/Pt/Au Schottky contacts with varying contact areas, complemented by back-side Ni/AuGe/Au ohmic contacts spanning the entire area. First, the reverse current-voltage characteristics of the prepared detectors were measured. The dependence of the reverse current and the breakdown voltage on the Schottky contact area was revealed. As the contact area decreases, the reverse current decreases and the breakdown voltage increases. The detection performance of the detectors was evaluated by alpha spectrometry using an 241Am source. After irradiation of the detectors from the Schottky electrode, the measured alpha spectra show an increasing CCE with decreasing Schottky contact area. Finally, the correlation between the applied bias voltage and the extent of the active detector area from the edge of the detector contact was investigated.