Polarization and wavelength dependence of metal-semiconductor-metal photodetector response

Abstract

Photocurrent and transmission studies for 543<λ<1523 nm of metal-semiconductor-metal (MSM) photodetectors on semi-insulating GaAs substrates demonstrate a polarization and wavelength dependence of the coupling of light into the metal electrodes. Devices with electrode periods of 400 and 800 nm were investigated and differences as large as 85% in efficiency between orthogonal polarizations were measured for the 400 nm devices. Modeling of the energy transmission through lamellar periodic structures using a Greens function formalism and incorporating dispersion of the substrate dielectric constant produces semiquantitative agreement with the measurements. Suggestions for future MSM photodetector design are discussed.