High breakdown voltage In/sub 0.52/Al/sub 0.48/As/In/sub 0.53/Ga/sub 0.47/As metamorphic HEMT using In/sub x/Ga/sub 1-x/P graded buffer

Metamorphic In/sub 0.52/Al/sub 0.48/As/In/sub 0.53/Ga/sub 0.47/As HEMT grown on GaAs with In/sub x/Ga/sub 1-x/P (x=0.48/spl rarr/1) graded buffer layer is reported. In this design the In/sub 0.53/Ga/sub 0.47/As channel layer was grown on top of the InGaP graded buffer directly without an InAlAs buffer as in the conventional design. The device shows high breakdown voltage: the measured on-state and off-state breakdown voltage are 11 V and 23 V, respectively, at a gate current of 0.1 mA/mm. The impact ionization rate and its dependence on temperature is also measured and analyzed, and the possible mechanism of the high breakdown voltage achieved is discussed. The metamorphic HEMT shows promising performance for its potential in power applications.