Ion-implanted high microwave power indium phosphide transistors

Encapsulated rapid thermal annealing (RTA) has been used in the fabrication of indium phosphide (InP) power metal-insulator-semiconductor field-effect transistors (MISFETs) with ion-implanted source, drain, and active channel regions. The MISFETs had a gate length of 1.4 μm. Six to ten gate fingers per device, with individual gate finger widths of 100 or 125 μm, were used to make MISFETs with total gate widths of 0.75, 0.8, or 1 mm. The source and drain contact regions and the channel region of the MISFETs were fabricated using silicon implants in semi-insulating InP at energies from 60 to 360 keV with doses from 1×10¹² to 5.6×10¹⁴ cm^-2. The implants were activated using RTA at 700°C for 30 s in N₂ or H₂ ambients using a silicon nitride encapsulant. The high-power, high-efficiency MISFETs were characterized at 9.7 GHz, and the output microwave power density for the RTA conditions used was as high as 2.4 W/mm. For a 1-W input at 9.7 GHz gains up to 3.7 dB were observed, with an associated power-added efficiency of 29%. The output power density was 70% greater than that reported for GaAs MESFETs