Millimeter wave distributed metal-semiconductor-metal photodetectors

Abstract

We propose and analyze a method for distributed photodetection using waveguide-coupled metal-semiconductor-metal (MSM) photodetectors. The electrode configuration is a coplanar strip waveguide capacitively loaded with the interdigitated MSM structure. The slow wave character of this structure allows for matching the velocity of the guided electrical wave to that of the optical waveguide resulting in virtually capacitance-free photodetection. In the context of actual device structures and operating conditions, the bandwidth limitation due to velocity mismatch and the influence of transmission line loss and dispersion on the high-frequency response are calculated and is found to be close to 1 THz. Thus, the detector structure is suitable for fully exploiting the transit-time-limited bandwidth potential of ≥200 GHz which is attainable by using interdigitated electrodes with ≤0.1 μm spacing and width.© 1995 American Institute of Physics.