Polyimide passivated semitransparent In0.49Ga0.51P/GasAs MSM photodetector operating at 840 nm wavelength

Abstract

A polyimide passivated semitransparent metal–semiconductor–metal photodetector (MSM–PD) with an In0.49Ga0.51P/GaAs layer structure has been fabricated and characterized. For a 50 μm×50μm device with 2 μm finger width and 2 μm finger spacing, we obtained a dark current density of 7.44 μA/cm2 for a passivated and 11.2 μA/cm2 for an unpassivated device at 10 V bias. The front illumination responsivity at 0.84 μm wavelength is 0.54–0.74 A/W at 10 V bias for both passivated and unpassivated devices. The dark current and responsivity of a passivated photodetector are nearly independent of the bias voltage as compared with those of an unpassivated photodetector. ©1999 John Wiley & Sons, Inc. Microwave Opt Technol Lett 22: 241–243, 1999.