Self-powered proton detectors based on GaN core–shell p–n microwires

Abstract

Self-powered particle detectors have the potential to offer exceptional flexibility and compactness in applications where size limits and low power consumption are key requisites. Here, we report on the fabrication and characterization of radiation sensors based on GaN core/shell p–n junction microwires working without externally applied bias. With their small size, high resistance to radiation, and high crystalline quality, GaN microwires constitute highly interesting building blocks for radiation-hard devices. Through microfabrication steps, single-wire devices were processed that show a leakage current as low as 1 pA in reverse bias. Irradiation with both UV light and 2 MeV protons results in photo/ionocurrent signals several orders of magnitude above the dark current and response times below 30 ms. The sensor also showed a good resistance to radiation. Although we observed a small increase in the leakage current after a prolonged proton irradiation, the measured transient ionocurrent signal remains stable during irradiation with a total proton fluence of at least 1×1016 protons/cm2.