Very low dark current InGaP/GaAs MSM-photodetectorusing semi-transparent and opaque contacts

Metal-semiconductor-metal (MSM) photodetectors have been fabricated for the first time in the InGaP/GaAs materials system. Extremely low dark currents 86 (±5) pA and 91 (±5) pA were obtained at 5 V bias using opaque and semi-transparent metal (tungsten) contacts, respectively. A front illumination responsivity of 0.37 A/W – 0.65 A/W at 5 V bias is obtained for a 50 µm × 50 µm device with 2 µm finger width and 2 µm finger spacing. The devices, operating at 840 nm, have a 3 dB bandwidth of >9.5 GHz for semi-transparent contacts, and 12 GHz with opaque contacts.