The impulse rise and fall times of biplanar vacuum photodiodes are experimentally investigated by the use of a single ultrashort laser pulse from a train of mode-locked pulses. It was confirmed that the impulse rise time is a function of the photoelectrons’ transit time from photocathode to anode, and that the impulse fall time is 2.2 times the capacitance of the photodiode and the resistive component of the load.
R. L. Smith and T. Honda, "Impulse Rise and Fall Times of Biplanar Vacuum Photodiodes," Appl. Opt. 12, 1606-1610 (1973)