Performance of a near-infrared GaAs metal-semiconductor-metal (MSM) photodetector with islands

A GaAs metal-semiconductor-metal (MSM) photodetector with ultrasmall gold islands deposited on its photosensitive surface is described. The interdigitated detector is fabricated on a semi-insulating substrate in a MESFET-compatible technology. Responsivity as high as 1.8 A/W is obtained at 0.86 mu m and a bias voltage of 8 V. This represents over a sixfold increase with respect to responsivity of a conventional MSM photodetector. The mechanism for dark current is suggested and breakdown characteristics are presented.<
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