Characterization of 1.8-MeV proton-irradiated AlGaN/GaN field-effect transistor structures by nanoscale depth-resolved luminescence spectroscopy

We have used depth-resolved cathodoluminescence spectroscopy to examine AlGaN/GaN modulation-doped field-effect transistors that display degraded source-drain current characteristics after 1.8-MeV proton irradiation, along with bulk heterojunction field-effect transistor material after similar proton irradiation. For both cases, we have observed distinct changes in spectral emission features due to decreased internal electric-field strength and new point defects within different layers of the device structure with nanometer-scale depth resolution. These changes can account for the degraded electrical characteristics.