For transient to test the bandwidth, the recombination parameters will not affect too much. But when using the ssac to test the bandwidth, the recombinations count a lot. For some situation, the bandwidth will decrease as the bias voltage increase and the UTC-PD bandwidth will decrease when using the graded doping in the absorption layer, it violate the principle. I want to know how to set the appropriate parameters in the ssac, the parameters in the example of vertical PD are not suitable for my model.