Interplay Between γ–Ray Irradiation and 3DEG for Dosimeter Applications

This work investigates the cumulative dose
⁶⁰
Co gamma (
$\gamma$
) – ray irradiation effects on enhancement mode HEMT devices inheriting 3D – Electron and Hole Gases for dosimeter applications. The devices are irradiated through a
⁶⁰
Co source and demonstrate the enhancement in the drain current metrics. To elucidate, the said devices were irradiated through different mechanisms and the Compton effect was investigated through contour plots via TCAD simulations. The degradation of Schottky Gate contact and insulator charging affects the 2D – Hole Gas at the GaN cap and thereby affects the bottleneck at the 3DEG sheet. This significantly affects the OFF – state leakage components of the said device and can therefore be exploited for potential use in sensing and dosimeter applications. The leakage components can be exploited further to improve the linearity of the dosimeter by considering different grading profiles of the AlGaN layer. In this regard, a workflow for optimizing the sensitivity and linearity of the dosimeter through different graded profiles is also presented. Amongst all, gaussian graded profiles have been identified as the best – case scenario considering the sensitivity and exhibiting a linear operation.