InAlGaAs fully quaternary heterostructure doped-channel FETs recessed by CH
F3 + BCl3 reactive ion etching have been fabricated. The etching selectivit
y was optimised by adjusting the flaw rate ratio of this gas mixture. The d
evice demonstrated good DC and microwave characteristics with a uniform dis
tribution of threshold voltages, which illustrated the advantages of the RI
E-recess process.