High-efficiency GaInAs Microwave MISFET´s

GaInAs metal-insulator-semiconductor FET\´s (MISFET\´s) fabricated with a self-aligned-gate process and 1-µm gate lengths gave power outputs as high as 857 (1.53), 424 (0.76), 415 (0.74), and 114 mW (0.20 W/mm) at 4, 12, 20 and 32.5 GHz, respectively. Power-added efficiencies of 64.3 and 55.0 percent were obtained at 4 and 12 GHz, respectively. At 20 GHz, a power-added efficiency of 32.5 percent was obtained. The value of calculated from measured scattering parameters (S parameters) was ∼ 45 GHz. This high cutoff frequency was validated by the measured performance at 32.5 GHz. We believe this to be the best microwave performance reported for GaInAs power transistors. A self-aligned-gate process, essential for minimizing gate overlap capacitances while maintaining a full-gate structure, that offers the potential for Submicrometer gate-length device fabrication is described.