Ti-gate metal induced PHEMT degradation in hydrogen

Through accelerated life test in hydrogen, we have found, for the first time, that in addition to Pt metal, Ti metal in a Ti/Pt/Au-gate PHEMT can also induce a significant hydrogen effect by reacting with a small amount of hydrogen gas in the ambient. The hydrogen sensitivity of a PHEMT device caused by Ti gate metal is significantly less than that due to Pt. Since Ti is not a hydrogen catalyst, the resulting hydrogen sensitivity indicates that a catalytic reaction between the gate metal and hydrogen gas is not required to have a detrimental hydrogen effect. The data also show that the degradation evident in the PHEMT devices due to the Ti-H/sub 2/ interaction is similar to that from the Pt-H/sub 2/ interaction. It is clear from this work that attempting to solve the hydrogen degradation problem by eliminating the Pt gate metal in a PHEMT is ineffective.