GHz response of metamorphic InAlAs metal-semiconductor-metal photodetector on GaAs substrate

We fabricated metal-semiconductor metal (MSM) photodetectors on the metamorphic InAlAs layer grown on a GaAs substrate. The devices were measured at a wavelength in the 0.8 mu m regime. The receiving area is 30 x 30 mu m(2) and the electrode spacings are 2, 1, and 0.4 mu m. At the electrode spacing of 1 mu m, a dark current of 125 nA was obtained at a bias voltage of -15 V. At a wavelength of 830 nm, a responsivity of 0.13 A/W was obtained at a bias voltage of -15 V. At a wavelength of 850 nm, the maximum bandwidth of 9 GHz was obtained at a bias voltage of -15 V. (C) 2014 The Japan Society of Applied Physics