Trap-assisted tunneling current of ultrathin InAlN/GaN HEMTs on Si (1 1 1) substrate

In this paper, the reverse gate leakage current mechanism of ultrathin InAlN/GaN high-electron mobility transistors on Si (1 1 1) substrate which treated with and without surface treatment process is systematically investigated. Current-voltage (I-V) measurement in temperature range from 273 K to 473 K and capacitance-voltage (C-V) measurement under 300 K are used to analyze the main leakage mechanism. For the whole reverse bias region (−30 V to 0 V), the best reasonable fitting calculation results correspond to the experimental values is based on trap-assisted tunneling (TAT) current mechanism, which indicates the dominant reverse leakage current of the ultrathin InAlN/GaN HEMTs device is derived from TAT current. N2 plasma surface treatment method is proposed to optimize the interface of the Schottky contact, which is an important way to reduce the reverse leakage current examined by the extracted values of trap energy levels (φt) and thermal activation energy (Ea) as well as XPS results. Further, for high reverse bias condition, electric field saturation across the barrier layer is not sufficient to support the slow rise trend of the TAT current, a modified electric field model was proposed to accurately explain this phenomenon.