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 350mum diameter detection area, theoretically limited capacitance values (0.75pF) and very low depletion voltages (< 1 V) were obtained. For an active layer thickness of 0.7mum, the devices show an external quantum yield of up to 60% and a bandwidth of 0.95 GHz at 10V bias.