200 GHz distributed InGaAs metal-semiconductor-metal photodetectors for the long-wavelength regime

摘要

Distributed InGaAs metal-semiconductor-metal photodetectors are presented which possess the potential to overcome the bandwidth limitations arising form the RC time constant and high optical power levels in lumpedelement detectors. The devices consist of vertically-coupled waveguide-integrated MSM detectors in conjunction with a coplanar waveguide transmission line. The slow-wave character of this structure alows for velocity-matching between the optical and electrical waveguide. Based on simulatoion calculations of representative device structures and operating conditions, design rules or wide-band operation >= 200 GHz are given. The results indicate that the absorption volume of velocity-matched distributed MSM detectors can exceed that of lumped-element devices by more than an order of magnitude without impairing the bandwith which results in a correspondingly larger optical saturation power. Essential device parameters used in device modeling are obtained from measurements of fabricated test structures.