Large-area low-capacitance InP/InGaAs MSM photodetectors for high-speed operation under front and rear illumination
Large-area long-wavelength metal-semiconductor-metal (MSM) photodetectors fabricated on the Fe-doped InP/InGaAs material system have been characterised under front and rear illumination employing different thicknesses of the photoactive layer. With a 350 µm diameter detection area, theoretically limited capacitance values (0.75 pF) and very low depletion voltages (< 1 V) were obtained. For an active layer thickness of 0.7 µm, the devices show an external quantum yield of up to 60% and a bandwidth of 0.95 GHz at 10 V bias.
