Investigation of the degradations in power GaN-on-Si MIS-HEMTs subjected to cumulative gamma-ray irradiation

Abstract

In this work, GaN-on-Si power Metal-Insulator-Semiconductor High Electron Mobility Transistors(MIS-HEMTs) are irradiated through different regimes of cumulative gamma-ray irradiation, namely 1, 2, 3, 4, and 5 kGy for the first sample; 1, 3, and 5 kGy for the second sample; 1, 5, and 10 kGy for the third sample; and 1, 10, and 20 kGy for the fourth sample. After each irradiation dose, drain current (ID), threshold voltage (I-g), and gate leakage current (Is) are electrically characterized in all the samples. An improvement in I-D with a shift in V-Th is observed in all the samples, which saturates after a higher irradiation dose. X-ray photoelectron spectroscopy (XPS) analysis confirms creation of nitrogen vacancies that act as donor and improves the I-D. No significant change in I-g is observed except for an increase in noise in gate leakage current. Scanning electron microscopy (SEM) shows the Al-based metallization pad degrades due to formation of small cavities. Finally, energy dispersive X-ray (EDX) analysis confirms the formation of Al native oxides due to gamma-ray irradiation.