Learning Forum

[Logeshwaran Venkatesapandian]

We need help with an issue, When we try to find the F3dB Bandwidth of the Ge photodetector we are facing a problem with a plateau region when we have high Optical generation as shown in the graph below. I need to know what is the reason for this plateau region and a solution to solve it. 

[Guilin Sun]

I believe this is physical, as you can see even at small power, there is a kink at higher frequecy. when the power is small, the device works at the linear I-V relation. When the power is large other physics is involved. 

To improve, please check if the material properties are properly set and all the physics are considered.

[Logeshwaran Venkatesapandian]

 

Thank you very much for your response. we figure out that there is an optical power screening effect at a higher optical generation rate. In that case, the Electric field is reduced and the saturation velocity (Vsat) of photo generated carrier is reduced.

So, we want to plot Drift velocity vs Electric field to extract the saturation velocity to check this effect. Can you please tell me how we can do that? As shown in the below referred graph. Thank you.