Bandwidth simulations of 10 Gb/s avalanche photodiodes

We have described numerical results of a high-bandwidth design of an InGaAs/InP APD without sacrifice in reliability and manufacturability. A thinner multiplication layer reduces avalanche time, and the optimised absorption layer thickness manages the speed trade-off between (i) the high avalanche gain required of a thin absorption layer and (ii) the hole and secondary electron transit times of a thick absorption layer. One-dimensional simulation suggests the possibility of good control of edge breakdown with an optimized design. Substantial further improvement in bandwidth is likely to require alternate design approaches such as a different material (e.g., Si or InAlAs) for the multiplication region and/or an optical waveguide structure.