Impacts on access resistance of InP high electron mobility transistors from wafer processing

In this work, the authors evaluated the access resistance of InP high electron mobility transistors (HEMTs) and their degradation during wafer processing. The transfer resistance, which was rarely separated from other components of the total access resistance of InP HEMTs in the literature, was found to be the dominant component of the access resistance. It was also found that the transfer resistance degraded during wafer processing. The selection of the ohmic metal stack and its impact on both the metal-cap contact resistance and the transfer resistance was also investigated. The observations in their experiments and relevant discussions in the report are expected to be useful in the identification of improvement opportunities in both material growth and wafer fabrication of InP HEMTs.