Study of Ga/sub x/In/sub 1×x/P layers grown on InP for HFET application

Abstract

The crystalline quality of tensile strained Gao.25ho.75P layers grown on InP substrates was investigated. Samples were grown by metal-organic molecular beam epitaxy. Little or no relaxation was found in Gao.25Ino.75P layers which were up 500A thick. Thicker layers exhibited anisotropic strain relaxation, and the main relaxation direction was [ li0 1. Using strain compensation we were able to reduce relaxation in 650A thick layers. HFET devices with a tensile 200A thick Ga0.25ho.75P barrier, a composite channel, and modulated channel doping were fabricated. The HFETs with 1 micron long gates exhibited a transconductance higher than 150 mS/mm for a wide range of gate voltages, and a breakdown voltage of 9V.