Silicon Avalanche Photodiodes (APDs) are currently proposed as readout devices for the electromagnetic calorimeters to be used in proposed new detectors. In the present paper the photon detection mechanism of APDs is investigated and we discuss possible APD structures that would be suitable for particle physics experiments. Calculations were made with a Single-Particle Monte Carlo simulation technique, written in Fortran. The results agree well with measurements made on commercial APDs. Based on this work, we suggest some changes which improve the performance of APDs as detectors for scintillation light. (C) 2000 Elsevier Science B.V. All rights reserved.