High frequency performance of Ga free barrier AlInN/GaN HEMT



In this work we present the highest frequency performance reported to date of an AlInN/GaN HEMT with a 2×150 μm configuration. The frequency performance reached was of a measured fT of 107 GHz and an fmax of 89.5 GHz. The device has an IDSS of 1.1 A/mm at a VGS of 0 V, an Imax of 1.3 A/mm at VGS of 1 V, and a gm-peak of 395 mS/mm. The gate length, LG, was 122 nm and a total barrier thickness, tbar, of 10.1 nm. This gives us an LG/tbar ratio of 12.1 with a high ft·LG product of 13 GHz·μm. The thin barrier thickness greatly contributed to the high frequency performance of the device by reducing the short channel effects. The contact resistance of a TLM structure next to the tested device is 0.42 Ω·mm. The epitaxial layer was grown by MOCVD on a 3” SiC substrate. Hall measurements, after passivation, revealed an average material sheet resistance, Rsheet, of 219 Ω/□, a sheet carrier concentration of 2.2×1013cm-2, and a mobility of 1320 cm2/V-s. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)