Modeling and realization of a high-gain homojunction a-Si:H bulk barrier phototransistor

We report an extensive analysis of amorphous silicon bulk-barrier phototransistors. Starting from a new analytical model for the device, we take into account the peculiarity of the material and, in particular, of the p-doped base, which we find to critically affect device operation. We demonstrate the possibility of obtaining lightly p-doped material suitable for high-gain devices, and we use the equilibrium model of defects in amorphous silicon as a guideline for our work. Finally, measurements on a number of high-gain devices verify our theoretical predictions.