Polarization engineering via InAIN/AIGaN heterostructures for demonstration of normally-off AIGaN channel field effect transistors

摘要

Normally-off AIGaN channel heterostructure field effect transistors (HFETs) have been proposed and investigated numerically by taking advantage of the polarization engineering perspective in Ⅲ-nitrides. The utilization of polarization-matched InAlN/AlGaN heterostructures shifted the threshold voltage to approximately 1.1 V for an Alo.3Gao.7N channel HFET. Compared to the AlGaN/GaN HFEF with a low breakdown voltage, the normally-off InAlN/AIGaN HFETs show substantially enhanced breakdown characteristics. Besides, the two-dimensional electron gas (2DEG) mobility in the InAlN/AlGaN HFETs exhibits much less reduction with the increasing temperature than that in the AlGaN/GaN HFET, according to the calculation of electron mobility dominated by alloy disorder scattering and polar optical phonon scattering. As a result, the temperature dependences of the power figures of merit based on the conduction loss consideration in terms of 2DEG mobility variation and Johnson figure of merit show superior potential for polarization-matched InAlN/AlGaN HFETs in high-power and high-frequency electronics applications particularly operating at elevated temperatures. This work provides a useful way for demonstration of normally-off AIGaN channel HFETs and is also helpful for design of future devices, which can be beneficially exploited from polarized Ⅲ-nitride heterostructures.