I was trying use Sentaurus to model the capacitance-voltage of a simple 2-electrode MOS device (SiO2(5nm)/Silicon(100 um)) with Ohmic contacts but I have run into some difficulty. I've followed examples in the text pretty closely but I'm finding that in accumulation the capacitance rises, hits a peak, and then falls again very sharply (see attached Image). Generally it never saturates near Cox. It gets worse if I move towards standard (500 um) wafer thicknesses.
I was wondering if anyone has had any experience with the small-signal analysis of MOS structures and could offer some advice.
Please find below the text from my sde and sdevice files.
Hello Kyle,
I have an excel spreadsheet model that I wrote that solves this exact problem - MOS capacitor. It does a numerical solution of the Poisson equation self consistent with standard semiconductor Fermi statistics. It also has optional corrections for quantum confinement in the inversion layer and poly depletion. It generates plots of charge - total, inversion, accumulation, depletion - and the associated voltages supported by each, as well as potential and E field. Capacitance - total and differential - is calculated as well. Happy to send you a copy and walk you through the basics of using it if you would like.
Regards,
John Snyder
Hi John,
Many thanks for your response. I was able to get the code working. I had made a error with the generation of the doping. I would certainly be interested looking at the model you have created. It would probably provide a lot more insight into the numerical fitting of semiconductor devices. Its hard sometimes to get this with a closed system like Sentaurus.
Hi Kyle,
Sorry for the delay getting back to you. The excel file is on my profile and can be downloaded. I've added a 'read me' tab that explains in some detail how the model works. Let me know if you have any trouble.
Regards,
John S
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