An analytical small-signal model for submicrometer n+-i-n+ traveling-wave photodetectors

A fully analytical small-signal model for investigating the frequency response of submicrometer n⁺-i-n⁺ traveling-wave photodetectors is derived. In order to properly account for nonstationary nonlocal phenomena characterizing submicrometer devices, the simple diffusive description of the carrier drift flux in a local driving field discussed by Torrese et al. in 2002 has been replaced by the hydrodynamic approach. The influence of the bias voltage on the transit time, as well as the bandwidth limitation due to the electrical wave reflections at both input and output ends of the detector are discussed.