The design and fabrication of an InP MESFET with excellent I-V characteristics are reported. A record high transconductance of 110 mS/mm was measured for a 1- mu m gate length direct-Schottky-contact InP MESFET, where the InP surface was not passivated or treated prior to the deposition of the gate contact. Microwave measurements show an f/sub max/ of 11.6 GHz for this typical nominal 1- mu m gate length device. A p-type planar doped layer was inserted between the buried n-type channel and the device surface at 18 nm from the gate metal. This planar layer enhances the Schottky barrier height and device performance. >