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Stiffness/Residual Vector Error - NaN/Inf findings

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Hi,

I am especially writing this, because there is no specific explanation I found online. I checked the BCs and other variables, but could not find any mistakes.

I am working on a semiconductor device that is basically n-doped homogeneously, has sizes 50um-15nm, and with a drain voltage 1V on the left boundary, source voltage 0V on the right, and a varying gate voltage at its top with a thin insulator gate of. Although I work on a supercomputer with 36gb ram, and making a mesh not much detailed, I gather the error attached as image.

The error does not happen when I sweep the gate voltage from around -13V to 20V, but whenever I start it from around -15V it just happens. The error contains NaN/Inf findings in the solution, not a convergence error or a iteration one I guess, but somehow a calculation error. The simulation works well for -13V to 20V of gate voltage, giving a nice plot, but not for below -13V.

Sometimes it is an undefined value in stiffness vector, sometimes a residual vector error.

I want to plot the ID-VG graph accordingly, but cannot see below -13V. Can't I simulate after some voltage level?

Any comments for a better simulation?

Thanks,

~bera


1 Reply Last Post 06.12.2015, 15:06 GMT-5

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Posted: 9 years ago 06.12.2015, 15:06 GMT-5
Please how can I solve these problems

undefined variable
- Variable comp1.tds2.u
- Geometry: geom1
- Domain: 4
Failed to evaluate operator Jacobian
- Operator: mean
- Geometry: geom1
- Boundaries: 13, 15, 17
Failed to evaluate variable Jacobian
- Variable: comp1.tds2.u
- Boundaries: 13, 15, 17
- Feature: Stationary Solver 2 (sol3/s2)
Please how can I solve these problems undefined variable - Variable comp1.tds2.u - Geometry: geom1 - Domain: 4 Failed to evaluate operator Jacobian - Operator: mean - Geometry: geom1 - Boundaries: 13, 15, 17 Failed to evaluate variable Jacobian - Variable: comp1.tds2.u - Boundaries: 13, 15, 17 - Feature: Stationary Solver 2 (sol3/s2)

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