Nanoscale metal-semiconductor-metal photodetectors fabricated on SOI-substrates

Summary form only given. Interdigitated metal-semiconductor-metal (MSM) Schottky diode photodetectors based on silicon-on-insulator substrates (SOI) are attractive due to their high speed achievable at long wavelengths. In this work, MSM-PDs have been fabricated on SOI substrates using electron-beam lithography and lift-off techniques. DC and transient characterization of the SOI-MSM-PDs show low detector dark current, low depletion capacitance, high speed and reasonable photoresponse. Two different photodetectors were investigated: MSM1 with finger width and spacing of 200 nm, an active area of 9.5/spl times/18 /spl mu/m/sup 2/ and a top p-type Si-layer thickness of 0.5 /spl mu/m, and MSM2 with finger width and spacing of 70/400 nm, an active area of 9.5/spl times/29.5 /spl mu/m2 and a top n-type Si-layer thickness of 4 /spl mu/m. In order to achieve the Schottky contact, MSM1 was metallized with Ti-Au (20/30 nm), while MSM2 was metallized with Al (30 nm).