Photodiode

摘要

The charge carriers generated photoelectrically outside the space charge zone of a photodiode must firstly diffuse to the edge of the space charge zone before they are extracted there by the electric field and accelerated to the neutral semiconductor region located opposite. Since the rate of diffusion is generally lower than the drifting rate, the dwell time of the charge carriers outside the field region increases and thereby leads to a higher recombination probability. The consequence of this is that the internal quantum efficiency is lowered and the switching times are lengthened. Consequently, in accordance with the invention, means are provided outside the space charge zone which generate a drift field which accelerates the charge carriers towards the space charge zone.