SMALL SIGNAL AND DC CHARACTERISTICS OF ULTRA-THIN GaN/AlN/GaN HFETs

This paper presents high performance device results using an ultra-thin AlN/GaN structure on sapphire substrate with a 100-nm T-gate. Excellent dc and RF characteristics are reported, including an extrinsic transconductance of 500 mS/mm and an extrinsic ft/fmax(U) ratio of 78/111-GHz which is among the highest reported for AlN/GaN HFETs. Low gate leakage results are also presented despite the small barrier thickness and absence of a gate dielectric. Modeling of the small signal parameters is also discussed to gain an understanding of the limiting and contributing performance factors.