Theoretical comparison of 0.35 mu m gate length GaAs and GaInAs HEMTs

The authors present a theoretical study of the performance of nearly identical 0.35- mu m-gate-length HEMTs (high electron mobility transistors) made from three different materials systems, GaAs-Al/sub 0.32/Ga/sub 0.68/As, In/sub 0.15/Ga/sub 0.85/As-Al/sub 0.15/Ga/sub 0.85/As, and Ga/sub 0.47/In/sub 0.53/As-Al/sub 0.48/In/sub 0.52/As. The calculations are made using an ensemble Monte Carlo simulation which includes the full details of real space transfer, the transport properties of the two-dimensional electron gas, nonstationary transport, and the two-dimensional electric field profile through the self-consistent solution of the Poisson equation. The performance of the devices, measured in terms of the current-voltage characteristic, transconductance, and cutoff frequency, is compared, allowing the effects of the material parameters on the device performance to be completely isolated and independently ascertained. It is found that the InGaAs-based devices well outperform the GaAs-AlGaAs device, consistent with recent experimental measurements. Of the three devices, the GaInAs-AlInAs structure and delivers the greatest current.<>