Polarization dependence of the temporal response of metal-semiconductor-metal photodetectors

The effect of grating diffraction on metal-semiconductor-metal photodetector temporal response is shown to be significant, and largest for devices with electrode periods less than the optical wavelength. This is related to a polarization dependence of the initial photogenerated carrier densities and distributions. With subpicosecond illumination, the measured difference in peak temporal signal for orthogonal polarizations was up to three times larger than that of the time-integrated photocurrent, and risetimes differed by as much as 30%. Transmission efficiencies obtained from coupled-wave analysis of metal grating structures on GaAs show excellent agreement with the time-integrated photocurrent measurements.