Gate length scaling study of InAlAs/InGaAs/InAsP composite channel HEMTs

The dependence of direct current and microwave performance of InGaAs/InAsP composite channel HEMTs on gate length is presented experimentally. Composite channel HEMTs with gate length from 1.13 μm to 0.15 μm were fabricated. Device characterization results showed the extrinsic transconductance increased from 498 mS/mm for 1.13 μm devices to 889 mS/mm for 0.15 μm gate devices, while the unity current gain cutoff frequency increased from 24 GHz to 190 GHz. A simple delay time analysis is employed to extract the effective carrier velocity (veff) of the composite channel. The veff is determined to be 1.9 × 107 cm/s. To our knowledge, this is the first systematic study on gate length scaling effect of composite channel HEMTs.