A simplified approach to time-domain modeling of avalanche photodiodes

A simplified algorithm for calculating time response of avalanche photodiodes (APD's) is presented, The algorithm considers the time course of avalanche processes for the general case of position-dependent double-carrier multiplications including the dead space effect, The algorithm is based on a discrete time setting ideally suited for computer modeling and can be applied to any APD structure. It gives a fast and accurate estimation of the time and frequency response of APD's, As an example, the present method is applied to InP-InGaAs separate absorption, grading, charge, and multiplication (SAGCM) APD's, The variation of multiplication gain with bias voltage and 3-dB electrical bandwidth at different multiplication gain obtained using the new algorithm show good agreement with experimental results, The algorithm can be used to study temperature dependence of APD characteristics and can he easily extended to calculate the excess noise factor.