Interface and Border Traps Study in Si₃N₄/AlN/GaN MIS-HEMTs With In-Situ N₂ or H₂/N₂ Plasma Pretreatment

This work investigated the impact of in-situ N2 or H2/N2 plasma pretreatment on the interface and border trap states between plasma-enhanced atomic layer deposition (PEALD) AlN and GaN in normally-off Si3N4/AlN/GaN MIS-HEMTs. The interface trap density with different time constants and the trap density at different energy levels of the interface traps are characterized by high frequency capacitance-voltage (HFCV) test and conductance method, respectively. The energy level & spatial distribution of the border traps and the border trap density are characterized by quasi-static capacitance C-V (QSCV) test and 1/f noise method, respectively. It is found that in-situ H2/N2 plasma pretreatment more effectively reduces the overall trap density compared to in-situ N2 plasma pretreatment. Moreover, both plasma pretreatment process has a greater suppression effect on the border traps than on the interface traps compared to no plasma pretreatment. And it is more effective at suppressing the shallow interface traps than the deep ones.