最大振荡频率为200 GHz的蓝宝石衬底AlGaN/GaN HEMT

本文报道了fmax为200GHz的基于蓝宝石衬底的AlGaN/GaN 高电子迁移率晶体管（HEMT）。外延材料结构采用了InGaN背势垒层来减小短沟道效应，器件采用了凹栅槽和T型栅结合的工艺，实现了Ka波段AlGaN/GaN HEMT。器件饱和电流达到1.1A/mm，跨导为421mS/mm，截止频率（fT）为30GHz，最大振荡频率（fmax）为105GHz。采用了湿法腐蚀工艺将器件的Si3N4钝化层去除后，器件的Cgs和Cgd减小，器件截止频率提高到50GHz，最大振荡频率提高到200GHz。

AlGaN/GaN HEMT with 200 GHz fmax on sapphire substrate with InGaN back-barrier

A gate-recessed AlGaN/GaN high electron mobility transistor (HEMT) on sapphire substrate having fmax of 200 GHz is reported. The gate-recessed device with a T-shaped gate exhibits a maximum drain current density of 1.1A/mm, and a peak extrinsic transconductance of 421mS/mm with minimum short-channel effects because of an InGaN back-barrier layer. A unity current gain cut off frequency(fT) of 30GHz and a maximum oscillation frequency(fmax) of 105GHz are obtained. After removing SiN by wet etching, the fT of the device increase from 30GHZ to 50GHz and the fmax increases from 105GHz to 200GHz, which result from a lower Cgs and Cgd after removing Si3N4.