A thin (200 Angstrom) WSix film is used to improve the light admittance, without sacrificing the Schottky performance, of InAlAs/InGaAs metal-semiconductor-metal (MSM) photodetectors. A 73% transmittance was achieved at a wavelength of 1.55 mu m. This thin layer followed by a thick layer of indium tin oxide (ITO), used as a gate material, demonstrated a responsivity of 0.44A/W, which corresponds to a 70% improvement compared with the conventional thick metal gate MSM detectors.
