Barrier height engineering on GaAs THz Schottky diodes by means of high-low doping, InGaAs- and InGaP-layers

Abstract

Barrier height engineering of n-GaAs-based millimeter-wave Schottky diodes using strained InGaAs/GaAs and InGaP/GaAs heterostructures and a high doping surface layer is presented. The Schottky barrier height can be varied between /spl Phi//sub fb/=0.52 eV and /spl Phi//sub fb/=1.0 eV. The use of a pseudomorphic InGaAs layer and/or a thin high doping layer at the surface significantly reduces the Schottky barrier height. This is advantageous for low-drive zero bias mixing applications, A full quantum mechanical numerical calculation is presented to simulate the influence of different high doping layer thicknesses on the diode's dc characteristic. The theoretical results are compared with experimental results, For reverse bias applications (e.g., varactors) a barrier height and breakdown voltage enhancement is realized with a lattice matched InGaP/GaAs heterostructure. The barrier height value is determined by temperature dependent dc-measurements. The epitaxial layered structures are grown by molecular beam epitaxy. The diode devices are fabricated in a fully planar technology using selective oxygen implantation for lateral isolation. The diode's cut-off frequencies are in the THz-range.