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By Umberto Ravaioli1, Nahil Sobh1
1. University of Illinois at Urbana-Champaign
View Resource (JAR)
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06 May 2012
4.0 out of 5 stars
This is a great tool for visualizing the effect of doping on semiconductor carrier concentration and Fermi level. The side-by-side representation of the band diagram with carrier concentration curve is very effective, and I _really_ value being able to see the equations used,their literature sources, and being able to look at the numerical values generated in real time as I change parameter values. The value of ni at 300K is not the one from Pierret that I usually use. At first I thought this was a problem, but perhaps it is not. The basic behavior is the same for both values, so the students can still gain conceptual insight provided by the graphical representation, and with the slightly different value of ni, students cannot just use the simulation to do their homework calculations of n and p as functions of Na, Nd, and T. Brief instructions for newcomers might be helpful, but the applet is intuitively designed so that forcing users to look at the values and think about what is happening may be useful for developing their understanding. From time to time, I get some inconsistent results with the java applet. The first time I ran the applet, ni at 300K was about 5 orders of magnitude off, and Ef was changing in equal energy steps for all doping concentrations, even for every low Nd = 10. When I went back to more carefully document what was wrong, the applet started behaving correctly. I’d like to see some mention that there is a third freeze-out region of behavior at even lower temperatures that is not represented.
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12 Feb 2008
5.0 out of 5 stars
It is good for the beginners. It will help in building their intuition about what happens to the semiconductor when temp and/doping are (is) varied.