Bulk GaN alpha-particle detector with large depletion region and improved energy resolution

Abstract

An alpha-particle detector was fabricated using a freestanding n-type bulk GaN wafer with a Au/Ni/GaN sandwich Schottky structure. Current–voltage measurements at room temperature revealed a Schottky contact with a leakage current of 7.53±0.3nA at a reverse bias of 200V. The detector had a large depletion depth that can capture much of the energy from 5.486MeV alpha particles emitted from a 241Am source. The resolution of its alpha-particle energy spectrum was improved to 2.2±0.2% at 5.486MeV under a bias of 550V. This superior resolution was attributed to the shortening of the carrier transit time and the large energy deposition within the large depletion depth, i.e., 27µm at −550V, which all resulted in a more complete charge collection. A model developed using the ATLAS simulation framework from Silvaco Inc. was employed to study the charge collection process. The simulation results were found to agree closely with the experimental results. This detector will be beneficial for research at neutron scattering facilities, the International Thermonuclear Experimental Reactor, and the Large Hadron Collider, among other institutions, where the Si-based charged particle detectors could be quickly degraded in an intense radiation field.