Metal-semiconductor-metal (MSM) photodetectors fabricated on MOCVD grown Hg1-xCdxTe

The fabrication of the first metal-semiconductor-metal photodetectors on Hg_1-xCd_xTe is reported using MOCVD grown layers on GaAs substrates. An epitaxial CdTe overlayer has been incorporated in the device structure for the enhancement of Schottky barrier characteristics. The interdigitated devices (2.3 mu m electrode width, 3.3 mu m spacing) exhibited a breakdown voltage of -60 V and responsivities of more than 1.0 A/W at a wavelength of 1.3 mu m and bias voltage of 40 V. Over the range of bias voltage examined, the dark leakage current of the detectors was dependent on the choice of contact metal, with minimum values of 10 nA at <1 V for Pt/CdTd/Hg_1-xCd_xTe.