I used Device to simulate the dark current of the vertical Ge-PD for 2V reverse bias voltage and for various length of the PD.
The simulated results are far from my measurement results (simulation results were much smaller than the measurement results for the length longer than 10um). I modified the bandgap parameter of the Ge and it improved the results. However, I still have noticeable differences for long length PDs.
I also try to use the interface material model, but I noticed that by adding the Si-Al interface and Si-Ge interface the dark current degrades while I expected the dark current increases.(the degradation of the dark current with Si-Ge interface is noticeable). Is there any specific setting for the interface models?
Further, when I add the Si-Al interface and consider the electrical surface recombination velocity for majority carriers also, the simulation stop due to the errors:
" Initialization failed to converge electrostatic potential update. Error: there was an unknown parallel error. the error code is 9002," what do these errors mean?
I have noticed that the simulated slope of the variation of the dark current for various PD’s area is smaller than the slope of the measurement results. I would appreciate if you suggest what parameter I should change to solve that issue. more precisely, I want that the dark current increases faster with increasing the PD’s area.