InP-based HEMT's with Al/sub 0.48/In/sub 0.52/As/sub x/P/sub 1-x/ Schottky layers

We report on the DC and RF performance of InP-based HEMT's with Al/sub 0.48/In/sub 0.52/As/sub x/P/sub 1-x/ Schottky layers and GaInAs/InP composite channels. By replacing the Al/sub 0.48/In/sub 0.52/As Schottky layer with Al/sub 0.48/In/sub 0.52/As/sub x/P/sub 1-x/ we have been able to increase the bandgap of the Schottky layer and achieve record breakdown voltages for 0.15 μm gate-length InP-based HEMT's. The 0.15 μm gate-length HEMT's have gate-to-drain breakdown voltages of over 13 V with current densities of 620 mA/mm and maximum transconductances of 730 mS/mm. On a wafer with a higher sheet charge we have obtained gate-to-drain breakdown voltages of 10.5 V with current densities of over 900 mA/mm. These are the highest breakdown voltages reported for 0.15 μm gate-length InP-based HEMT's with such high current densities. At 10 GHz a 450 μm wide HEMT has demonstrated 350 mW (780 mW/mm) of output power with power-added efficiency of 60% and 12 dB gain.