GaAs metalsemiconductormetal photo-detectors (MSM PDs) with a variety of nano-scale finger spacing and widths were fabricated using nano-imprint lithography (NIL). The NIL process involves molding a MSM with inter-digitized fingers on a silicon substrate. Next, a layer of polymethylmethancrylate (PMMA) was spun on a semi-insulating (SI) GaAs substrate. Before imprinting, both the mold and the PMMA coated substrate were heated up to 175 °C, well above the glass transition temperature of the PMMA (105 °C). The MSM produced with the digitized finger method (NIL) was compared with MSM-PDs fabricated using electron-beam lithography. The MSM-PDs fabricated using NIL do not show observable degradation in the device characteristics if the imprinting pressures are kept at 600 psi or below, although they do degrade at higher pressures. Amongst others, degradation was observed for the MSM PD samples imprinted at 900 psi, where the average dark current was increased and the range of variation in dark currents was widened.
Key words: Nano-imprint, lithography, metal-semiconductor-metal, photo-detector, electron beam lithography
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