High performance InP-based HEMTs with dry etched gate recess for the fabrication of low-noise microwave oscillators

In this paper, a technology for the fabrication of high performance InP-based HEMTs using dry gate recess etching is reported. The dry etched devices show better uniformity and considerably reduced low-frequency noise compared to conventionally wet etched ones. As an application of the technology, a dielectric resonator oscillator (DRO) operating in the frequency range of 23.2-24.8 GHz was designed and fabricated using dry or wet etched InGaAs-InAlAs-InP HEMTs. An output power of 12 dBm and a phase noise of -107 dBc/Hz at 100 kHz offset from the carrier were measured for DROs with dry etched HEMTs. These values were superior by nearly 10 dB to those obtained with conventionally wet etched devices. The reduction in phase noise is attributed to hydrogen trap passivation during dry gate recess etching with a methane/hydrogen plasma.