Depletion/enhancement mode InAlAs/InGaAs-MOSHEMTs with nm-thin gate insulating layers formed by oxidation of the InAlAs layer

Photoluminescence intensity of an oxidized InAlAs initially decreased in a short period, then recovers by few hours oxidation. That of nitridated InAlAs gradually and monotonously decreases until 8 hours. Nitridation after oxidation of InAlAs does not increase the photoluminescence intensity. We fabricated the recess gate InAlAs/InGaAs-MOSHEMT based on the above experiment in which 5 nm thin oxide layer is formed by ozone process. The transconductance of the MOSHEMT is 200 mS/mm for a gate length of 1.5 /spl mu/m.