0.1-/spl mu/m InAlP/InAlAs/InGaAs/InP HEMTs with improved breakdown voltages

InAlP/InAlAs/InGaAs/InP HEMTs that offer improved breakdown voltages and reduced gate leak currents are investigated. The InAlP-layer has a larger etching selectivity compared to InAlAs and InGaAs, which is very effective in Vth control. Moreover, it has a larger Eg and Schottky barrier values than InAlAs and InP. These characteristics are suitable for the HEMT's etch stop layer. A fabricated 0.1-/spl mu/m HEMT exhibits 8.1 V breakdown voltage and 1-nA/10-/spl mu/m gate leak current without any performance tradeoff. These results are enough to expand the application area of InP-based HEMTs.