High-efficiency GaAs microwave power MESFETs with an n+n-n doping formed by buried-shallow-implant (BSI)

GaAs power FETs have been fabricated with an n⁺n^-n doping profile formed by a new buried-shallow-implant (BSI) process. This technique, which buries a thin precisely controlled active layer below the less critical capping layers, has produced high-efficiency devices with gate-drain breakdown voltages 30% higher than similarly processed all-implanted controls. Power-added efficiencies of 42% at 12 GHz, 46% at 10 GHz, and 52% at 8.5 GHz were measured from an initial test sample at an output power level of 200 mW. MMIC feedback amplifiers fabricated on the same wafer have also shown high-efficiency performance.