Performance of semi-insulating metal-semiconductor-metal GaN prototype devices as ionizing radiation detector

Abstract

We describe the fabrication and characterization of semi-insulating GaN devices for the detection of ionizing radiation with applications in high radiation environment. We present the DC characterization and the signal response of such devices from Am-241 α-source. The detector prototypes show up to 80% charge collection efficiency with bias voltages as low as -40V. Wide band gap semiconductors like synthetic diamond, GaN, SiC have gained immense importance in the field of charged particle detection due to their low intrinsic noise and high radiation tolerance. The ability of suppressing the thermal noise generated by intrinsic carriers, makes the fabrication of these devices simpler when compared to the multi-step lithography required for doping of traditional silicon-based solid-state detectors. We have made interdigitated metal-semiconductor-metal(MSM) device on a 3μm in thick GaN epitaxial layer grown on sapphire substrate by MOCVD technique. We employed Ni/Pt/Au metal stack for Schottky contact with finger width of 4μm, spacing of 8μm and finger length of 120μm. Details of the experimental set-up for fabrication and characterization will be presented.