Responsivity enhancement of InGaAs based MSM photodetectors using 2DEG layer sequence and semitransparent electrodes

The optoelectronic behaviour of InGaAs based metal-semiconductor-metal photodetectors with semitransparent electrodes is investigated. The devices with 50 x 50 mu m(2) area and interdigitated electrodes with 2 mu m finger-spacing and finger-width exhibit a dark current density less than 10pA/mu m(2), a breakdown voltage of 45V and a saturation capacitance of 30fF. A DC responsivity of 0.61 A/W and a-3dB bandwidth of 8.5GHz were achieved. The electric potential distribution is modified by a 2DEG inserted in the layer structure leading, to improved bandwidth.