在蓝宝石衬底上研制了具有高电流增益截止频率(fT)的InAlN/GaN异质结场效应晶体管 (HFETs).基于MOCVD外延n+-GaN欧姆接触工艺实现了器件尺寸的缩小, 有效源漏间距(Lsd)缩小至600 nm.此外, 采用自对准工艺制备了50 nm直栅.由于器件尺寸的缩小, Vgs= 1 V下器件最大饱和电流(Ids)达到2.11 A/mm, 峰值跨导达到609 mS/mm.根据小信号测试结果, 外推得到器件的fT和最大振荡频率(fmax)分别为220 GHz和48 GHz.据我们所知, 该fT值是目前国内InAlN/GaN HFETs器件报道的最高结果.

Scaled InAlN/GaN heterostructure field-effect transistors (HFETs) with high unity current gain cut-off frequency (fT) on sapphire substrate were fabricated and characterized. In this device, scaled source-to-drain distance (Lsd) of 600 nm was realized by metal organic chemical vapor deposition (MOCVD) based on regrow nonalloyed n+-GaN Ohmic contacts. Moreover, a 50 nm rectangular gate was fabricated by self-aligned-gate technology. A high drain saturation current density (Ids) of 2.11 A/mm @ Vgs= 1 V and a peak extrinsic transconductance (gm) of 609 mS/mm were achieved in the InAlN/GaN HFETs. In addition, from the small-signal RF measurements, the values of fT and maximum oscillation frequency (fmax) for the device with 50-nm rectangular gate were extrapolated to be 220 GHz and 48 GHz. To our best knowledge, the value of fT is the best reported one for InAlN/GaN HFETs in China.