Design optimisation of AlGaN/GaN metal insulator semiconductor high electron mobility transistor with high‐K/low‐K compound gate dielectric layer for millimeter‐wave application

Abstract

A novel high DC and radio-frequency (RF) characteristics AlGaN/GaN metal insulator semiconductor high electron mobility transistor (MIS-HEMT) with a high-K/low-K compound gate dielectric layer (CGD) is proposed. Owing to the different dielectric constants, the discontinuity of the electric field at the high-K/low-K interface can modulate the distribution of the electric field along the channel under gate. Hence, enhancement of DC and RF characteristics can be achieved. The optimised results of the AlGaN/GaN MIS-HEMT with CGD structure revealed that the DC transconductance gm and the maximum saturation current Ids increased about 10.5 and 6.9% compared with the traditional AlGaN/GaN MIS-HEMT with single high-K gate dielectric layer (SGD), respectively. Also, the cutoff frequency ft and the maximum oscillation frequency f max of 74.2 GHz and 129.2 GHz are obtained and improved about 18.5 and 14.7% compared with the device with SGD structure.