Simple model of electron-bombarded CCD gain

In earlier work, a model of the back illuminated CCD was presented and used to predict optical quantum efficiency. In this work we expand on the model and find an analytical solution for the probability of collection of a carrier generated at a given depth. We apply our solution to find the theoretical quantum efficiencies for both electron bombardment and optical illumination and compare them to measurements taken on thinned, backside-enhanced, non- AR coated devices. A single set of parameters is found which shows a reasonable fit to both sets of data. Earlier models of electron-bombarded CCDs have failed to explain the measured nonzero gain at low energies, however our model shows nonzero gain at all energies.