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Anonymous @ 11:28 AM on 31 Mar, 2010
Error clarification
Hello,
I’m getting the following error when I run a simulation:
can’t read “total vstep” : no such variable hile executing
“expr $total_vstep” file “apps/omenwire/r91/rappture/omenwirewr” line 1)
Could you please explain to me what this error means?
I’m applying a minimum gate voltage of -0.6V and maximum of 0V.
Thank you.
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SungGeun Kim @ 11:14 AM on 02 Apr, 2010
Hi, I actually got results, but it seems that simulation had some convergence problem, which means that the convergence criterion is hardly met and the results don’t seem to be right. Let me further assist you if you really need to simulate this structure. My e-mail address is kim568@purdue.edu and please tell me why you are doing this simulation and what the analytical(or qualitative) solution looks like.
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SungGeun Kim @ 01:53 PM on 01 Apr, 2010
Thank you for your question, but I couldn’t duplicate the situation. Could you tell me what other parameter you changed from the default?
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Ahmet Ceyhan @ 02:00 PM on 01 Apr, 2010
Hello, I was trying to simulate the following structure: Circular nanowire with n++ doped source, intrinsic channel and p++ doped drain. Vds=-0.6V, Vgmin=-0.6V Vgmax=-0.1V. The length of the channel is 20nm and the source and drain extensions are 15nm each. Thank you.
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SungGeun Kim @ 02:45 PM on 01 Apr, 2010
Could you specify the doping density for each region? Thanks
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Ahmet Ceyhan @ 10:07 AM on 02 Apr, 2010
The donor doping in source is 10e20 and acceptor doping is 10e6. Donor doping in drain is 10e6 and acceptor doping is 10e20.
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SungGeun Kim @ 02:57 PM on 01 Apr, 2010
The error you’ve got is possibly due to simulation failure or no outputs or convergence failure. The total_vstep is read from the output that includes the bias steps that you have applied. If that variable doesn’t exist, that means the simulation doesn’t have any output for your simulation. I am trying to mimicking the simultion with the parameter what you said on this comment.I will come back to you with the output that simulation gives me.
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Ahmet Ceyhan @ 10:09 AM on 02 Apr, 2010
I did get simulation results before using the same structure only with different voltage values. Is there a problem with the tool when you apply large negative gate voltage values such as -0.6V. I will be waiting for the results that you get. Thank you.
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SungGeun Kim @ 11:21 AM on 02 Apr, 2010
There is no reason that you would have problem when you use large negative gate voltge. What was the gate voltage that you used before?
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SungGeun Kim @ 11:24 AM on 02 Apr, 2010
At this point, let me mention that you may want to use different gate workfunction. I got 1e-21 A at Vg=-0.6V for your structure. This is too small and there is some convergence issue, so you may want to increase the number of maximum poisson iteration from 15 to 30 or higher even though that doesn’t gaurantee convergence.
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Ahmet Ceyhan @ 02:02 PM on 01 Apr, 2010
Sorry I forgot to mention that the channel diamter is 2.5nm and the oxide thickness is 1nm.
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Benjamin P Haley @ 12:16 PM on 01 Apr, 2010
Hi, hanks for reporting this issue. Let us look at the code and get back to you with an answer.
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