Long-wavelength In0.53Ga0.47As metamorphic p-i-n photodiodes on GaAs substrates

Metamorphic In0.53Ga0.47As p-i-n photodiodes on GaAs substrate exhibiting t he lowest dark current ever reported were fabricated and characterized. The ir dark current, DC and RF performances were measured and compared for devi ces of different sizes. Typical dark current for 15-mum-diameter devices wa s 600 pA under 5-V reverse bias, corresponding to a dark current density of 3.40 x 10(-4)A/cm(2). Typical responsivity measured with 1.55-mum optical radiation was 0.55 A/W, corresponding to an external quantum efficiency of 44%. The electrical 3-dB bandwidths of the photodiodes with diameters small er than 20 mum were over 20 GHz.