Help with DEVICE script in Germanium-on-Silicon Lateral Photodetector example



In the script provided with the example (Germanium-on-Silicon Lateral Photodetector), line 105 is:
anode = getresult(‘Device region’,‘anode’);
however Device region does not have an anode property, to get the results. I haven’t been able to find a way to extract the voltage sweep results. any suggestions where I should look for, I want to plot the dark current vs. voltage.



Hi @alireza. The Device region usually provides the following results, bandstructure, charge, doping, electrostatics, mobility, and recombination. These are also included in the list under the ‘Results’ tab in the edit properties window of the Device region. However, the solver also provides results for all the electrical contacts which is not part of this list as the name and number of electrical contacts vary from one simulation to the other. In the project file of this particular example, there are three electrical contacts, anode, cathode, and body (you can see them in the ‘Electrical contacts’ window at the bottom). These electrical contacts allow you to apply bias voltages and sweep them to get I-V characteristics. If you go into the edit properties window for the ‘anode’ contact, you will see that it is set to sweep from 0 V to -3 V. If you run the simulation without modifying anything (i.e. with the optical generation objects all disabled), the Device region will have results (datasets) named after the contacts (i.e. anode, cathode, and body) after the simulation is run. If you visualize (for example) the dataset ‘anode’, it will show you the current at that contact as a function of the applied voltage.


Hi @aalam. In the vertical Vertical SiGe photodetector example, in the Device file, when I want to run the temperature sweep I get the attached error

I can fix it by choosing the ::model::Charge::simulationTemperature instead of the “device region” and choosing Charge::Cathode.I.
But the result for dark current at -1 volts does not match the reference publication.
In addition for the photocurrent the result anode.I is used which is just cathode.I with different polarity. meaning the photocurrent and dark current are the same, which is wrong.
It is not clear to me what exactly the following results are:
Cathode.I, Cathode.Id, Cathode.In, Cathode.Ip, (same values for anode)
Where can I find more about this? which one presents the photocurrent and which presents the dark current?


Also after running the simulations the results that are generated are different from the results that are presented on the KB.


Hi. This simulation was modified recently and I am guessing some parameter needs updating. You can see that the nature of the curves are very similar and most likely it is missing a normalization factor somewhere. I will take a look at it and get back to you.

One thing to note here is that when you simulate for photocurrent, you will need to turn the optical generation object on. Since you are seeing identical photocurrent and dark current values, I am guessing that you did not enable the “gen” object.

The current values are reported for each contact. The name format is “contactname.I”. Here “I” refers to total current, “In” refers to electron current, “Ip” refers to hole current, and “Id” refers to displacement current (nonzero for transient simulation only).