AlGaAs/InGaAs Pseudomorphic Doped Channel Field Effect Transistor with A P-AlAs Buffer Layer Grown by Metalorganic Chemical Vapor Deposition

Abstract

An AlAs buffer layer was successfully utilized in a 0.25-µm-gate pseudomorphic doped channel field effect transistor for the first time by growing a high quality p-AlAs layer by metalorganic chemical vapor deposition that attenuated the commonly observed roughness-induced degradation. Compared with a device containing a thick GaAs buffer layer alone, the RF gm/gDS ratio and fmax in this device were increased by 42% to 39 and by 19% to 160 GHz, respectively, at the expense of a slight decrease in gm and fT. As a result of the reduced leakage conduction through the buffer layer at high temperatures, the fabricated doped channel FET with the p-AlAs buffer layer was completely pinched off and it exhibited excellent DC current–voltage characteristics even at elevated temperatures up to 200°C.