Characterization of GaN MOS Structures Using Photoanodically Grown Oxides with Respect to FET Devices

ABSTRACTPhotoanodically grown Ga2O3 layers were characterized with respect to their suitability as gate dielectrics for GaN based MOSFET Device applications. The Ga2O3 layers were produced in a photoelectrochemical cell using aqueous solutions of KOH. IV characterization of MOS structures show insulating behavior of the oxide layers and CV measurements indicate a small density of states at the oxide/GaN interface. Integrating the wet chemical oxide growth in a MOSFET device fabricating process includes tungsten as gate metal together with H2O2 as etching solution for the gate metal. Source/drain areas were made free of oxide by the alkaline developer of a conventional lithographic step and metallization was done by using the liftoff technique. MOS structures show no inversion mode but strong depletion in reverse biasing mode.