InGaAs metal-semiconductor-metal photodetectors with a hybrid combination of transparent and opaque electrodes

A metal-semiconductor-metal photodetector (MSMPD) with a hybrid combination of transparent cadmium-tin-oxide and opaque Ti:Au electrodes is proposed and demonstrated. A significant decrease in dark current is obtained by independently engineering the Schottky barrier heights at the anode and cathode. In addition, the use of transparent electrodes enables more light to be coupled into the front-side illuminated MSMPDs thereby increasing the responsivity. For an applied bias of 5 V, these devices exhibited an extremely low dark current density of 21.2 fA/μm2 and a high responsivity of 0.56 A/W to perpendicularly incident 1.31 μm wavelength light.