Effect of gate length on device performances of AlSb/InAs high electron mobility transistors fabricated using BCl ₃ dry etching

In this paper, we present the development of a mesa isolation process for AlSb/InAs high electron mobility transistors (HEMTs) using inductively coupled plasma (ICP) etching with BCl ₃ gas. Devices with different gate lengths (L _g: 60, 100, and 200 nm) fabricated by this dry etching technique show good DC and RF performances. With an appropriate L _g/gate-channel distance ratio, the 200-nm-gate has very high peak transconductances of 781mS/mm at V _DS = 0:1 V and 2000mS/mm at V _DS = 0:5 V. Moreover, an extrinsic current gain cutoff frequency of 137 GHz and maximum oscillation frequency of 97 GHz were achieved at a drain bias voltage V _DS = 0:3 V, indicating the great potential for such a device operating at high frequency with extremely low DC power consumption.