Resonant-cavity Schottky photodetectors with a grating profiled surface

Modeling of the optical response and quantum efficiency (QE) of a photodetector having a metal clad dielectric microcavity with periodic texturing of the top-metal electrode is examined at an optical communication wavelength (λ=1.3 μm). It is shown that microstructuring the top-metal layer allows coupling to surface plasmons and leads to practically zero top reflectivity near normal incidence. This is significantly lower than that of a planar counterpart structure the top reflectivity of which is in excess of 90%. The calculated efficiency using a Monte Carlo method is compared with that obtained analytically to demonstrate the effect of elastic and inelastic carrier scattering on the overall yield. The variations of both the efficiency and the bandwidth as a function of the active layer thickness suggests that the increase in the QE when increasing the active layer width is much less important compared to the very pronounced decrease in the bandwidth.