Sub-100 nm Gate Length GaAs MESFETs Fabricated By Molecular Beam Epitaxy And Electron Beam Lithography

Ultra-high resolution electron beam lithography (UHREBL) has been used for many years to write nanometer scale patterns in various materials. In 1960, sub-100 nm features were made in thin membranes1. Only recently has UHREBL been applied to fabrication of electronic devices2. Our laboratory is very interested in investigating the device physics of traditional electronic devices with nanometer features and novel devices that depend on the nanometer features for proper operation. Here we describe the fabrication and the device characterization of the former, specifically MESFETs with recessed gates as short as 65 nm. The high frequency performance of MESFETs is improved primarily by reducing the gate length, parasitic source and gate resistances, and the gate capacitance. An optimized short gate length device will reduce the noise figure and increase fmax for microwave amplifiers. In this paper, we also discuss the advantages of using a high Tc superconducting gate electrode for ultra-submicron FETs as a means to reduce the gate resistance.