Performance of a quarter-micrometer-gate ballistic electron HEMT

The electrical properties of a quarter-micrometer-gate HEMT have been studied by simulation and experiment. An I
DS
of 11 mA/50 µm, a g
m
of 500 mS/mm, and an f
T
of 110 GHz have been predicted by two-dimensional Monte Carlo simulation for certain conditions. The reasons underlying the high performance are discussed in terms of the electron dynamics in the device. A record room-temperature propagation delay time of 9.2 ps/gate at a power dissipation of 4.2 mW/ gate with the maximum transconductance of 400 mS/mm was obtained experimentally for a 0.28-µm-gate HEMT. Only a negligible short-channel effect was observed for reducing the gate length from 1.4 to 0.28 µm.