High-power high-efficiency stable indium phosphide MISFETs

In P MISFETs with gate widths up to 1 mm using SiO2as the gate insulator have been fabricated. At 9.7 GHz the highest power output with 4 dB gain was 4.5 W at 46% power-added efficiency corresponding to a power density of 4.5 W/mm of gate width. The maximum power-added efficiency for the same device and frequency was 50% at 3.8 W and 3.8 dB gain. This power is more than 3.5 times the previously reported maximum for InP FETs at 15% higher power-added efficiency and the power per unit gate width is more than three times that of the best GaAs FET. Power output was stable to within 2% over 167 hours of continuous operation.