The passivation mechanism of nitrogen ions on the gate leakage current of HfO2/AlGaN/GaN MOS-HEMTs

In this paper, we systematically study the positive gate leakage current in AlGaN/GaN metal-oxide-semiconductor high electron-mobility transistors (MOS-HEMTs) with HfO 2 dielectric using atomic layer deposition (ALD). We observe that the incorporated nitrogen ions will improve the positive gate leakage current of devices obviously, but do not change the reverse gate leakage current. The passivation mechanism of nitrogen ions in oxygen vacancies in HfO 2 is studied by first-principles calculations. It is shown that the gap states of HfO 2 caused by oxygen vacancies increase the positive gate leakage current of MOS-HEMTs. Nitrogen ions passivate the gap states of HfO 2 and decrease the positive gate leakage current but do not effect the reverse gate leakage current.