Nanoscale mapping of temperature and defect evolution inside operating AlGaN/GaN high electron mobility transistors

We used depth-resolved microcathodoluminescence spectroscopy (DRCLS) and Kelvin probe force microscopy (KPFM) to measure and map the temperature distribution and defect generation inside state-of-the-art AlGaN/GaN-based high electron mobility transistors (HEMTs) on a scale of tens of nanometers during device operation. DRCLS measurements of near band edge energies across the HEMT’s source-gate-drain regions reveal monotonic temperature increases across the submicron gate-drain channel, peaking under the drain side of the gate. DRCLS defect emissions mapped laterally and localized depthwise near the two-dimensional electron gas interface increase with device operation under the drain-side gate and correlate with higher KPFM surface potential maps.