Reliability of metamorphic HEMTs on GaAs substrates

Metamorphic HEMT (MHEMT) technology enables the growth of high indiurn content channels on GaAs substrates, giving them the performance of InP HEMTs. MHEMT growth techniques use a graded alloy composition layer structure, permitting channel In contents exceeding 25% without strain. Potential applications include 40 Gb/sec fiber as well as LNAs for LMDS and satellite communication. Many such applications place stringent requirements on reliability with Belcore standards requiring 10⁶ hrs Mean Time to Failure (MTTF) at 125C for power devices. Satellite applications require a LNA projected failure-free service of 15-30 years at 80C, which implies an 80C MTTF of approximately 10⁷ hours. Naturally, one will ask "Is MHEMT technology reliable?" From the results of our ongoing work, we show MHEMT reliability to be similar to InP HEMTs\´ with ∼10⁶ hours MTTF at 125C.