Breakdown in millimeter-wave power InP HEMTs: a comparison with GaAs PHEMT's

In spite of their outstanding transport characteristics, InP high-electron mobility transistors (HEMTs) deliver lower output power than GaAs pseudomorphic HEMTs (PHEMTs) throughout most of the millimeter-wave regime. However, the superior power-added efficiency of InP HEMTs when compared with GaAs PHEMTs makes this technology attractive for many applications. The reason for the relatively inferior power output of InP HEMTs lies in their comparatively small off-state and on-state breakdown voltages. This paper reviews the state of knowledge regarding the physics of breakdown voltage in InP HEMTs, placing it in contrast with GaAs PHEMTs. It also presents current understanding regarding burnout, a closely related phenomenon. This paper concludes by discussing strategies for improving the breakdown voltage and the power output of InP HEMTs.