So the current through a diode as a function of applied voltage is:(adsbygoogle = window.adsbygoogle || []).push({});

I = I_{0}[ exp( V q / K_{B}T) - 1 ]

where V is the voltage (independent variable), q is the charge of the electron (constant), T is temperature (constant over each trial), I_{0}is some parameter that's measured to be really tiny (I don't know why it exists, but I'm sure semiconductor theory can explain it), and K_{B}is Boltzmann's constant.

The circuit I built was just a diode and a resister in series. A voltage sweep from 0 - 10V was applied. The voltage is measure before and after the resister, and V_{applied{/SUB] - Vdrop over the resister is V across the diode. I is determined by Ohm's law applied to the voltage drop across the resister. So I fit the above equation to an I vs. V graph, and tried it with a bunch of temperatures and got several roughly equal values for KB, and did a weighted average over them. The problem is, it's almost exactly double the real value of KB. My lab report has already been marked and handed back, and the mark was pretty good; the TA made a note saying: "This KB is exactly what you should've gotten with this experimental setup." I totally don't understand what that means though. What might've gone wrong with my measurement technique? Or is this "mistake" actually intrinsic to the diode? The note certainly implied that the data analysis is all correct.}

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# Measuring the Boltmann constant by the IV curve of a diode

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