Performance enhancement using WSix/ITO electrodes in InGaAs/InAlAs MSM photodetectors

A thin (200 Å) 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 µm. This thin layer followed by a thick layer of indium tin oxide (ITO), used as a gate material, demonstrated a responsivity of 0.44 A/W, which corresponds to a 70% improvement compared with the conventional thick metal gate MSM detectors.