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Philip David Flammer

deep accumulation for small devices carrier density/availability of customizable PADRE

I have a question about the effectiveness of this tool in predicting carrier density for accumulation situations at say (5 V) for thin devices (2-3nm high k oxide) in the high frequency regime. When I look at the carrier concentrations, I can’t get enough points close to the surface (due to the limitation of the grid—1000 points in the semiconductor) to get convergence. Is there a way to increase the number of points possible in the silicon, or is it fair in the model to solve a thick silicon model, and then thin it down setting the edge carrier concentration equal to what it was at that point in the thicker model (to get a smaller grid)?

Also, do you know if PADRE is a free software that I can obtain to run custom simulations, or is it commercial? I haven’t been able to find information on this.

Thank you very much in advance!

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    michael duane

    Have you tried using fewer grid points (like 100) if you are having convergence issues? and/or how thick is your silicon? 1um would be more than enough for the conditions you describe (which you can tell by checking the carrier concentrations and potentials at the last bias point).

    the online help mentions how PADRE came from Bell Labs and that if you are interested in QM effects, you should be using SHRED.


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      Philip David Flammer

      I think I didn\‘t pose the question correctly. It\‘s not that I am concerned with the solution not converging in the sense that it says it isn\‘t converging. I am looking at the 2D electron gas that is created at the interface between the oxide and silicon, and am concerned that I don\‘t have enough points near that surface to truly converge to the correct carrier concentration at that surface.

      I have attempted silicon thicknesses of 1um,500nm, and 100nm to see how this effects the carrier concentration and to increase the point density near the surface.

      I don\‘t think I have to deal with QM effects since the population is so high in that area that i should have enough states filled to approach the classical result?

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      Philip David Flammer

      It appears that someone fixed it so that now it meshes more densely near the oxide boundary. Thanks to whomever did that.

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