Electron transit time of PIN photodiodes fabricated in two-valley semiconductors

Electron transit time was calculated for a PIN photodiode with the absorption layer realized in two-valley semiconductor (GaAs, InGaAs...). Non-stationary effects and changes of the electric field along the layer result in a dependence of the electron transit time on both the applied voltage and the thickness of the layer. This dependence shows marked maximum and minimum, which could be important when modelling the response times of PIN photodiodes fabricated in these materials.