High transconductance InAlAs/InGaAs double heterostructure MESFETs with in-situ aluminum oxide gate barrier

By incorporating an in-situ aluminum oxide gate barrier in InAlAs/InGaAs double heterostructure FETs we have reduced the gate leakage current by more than an order of magnitude. The measured transconductance is 130 mS/mm and the device pinches off at -1.5 V. The oxide barrier is prepared by in-situ deposition of 2 nm Al in an MBE system followed by complete oxidation in air or during exposure to an oxygen plasma. The device structure and fabrication process is readily scaled to submicron gate lengths.