I want to fit the I-V curve of a diode using the diode equation. The I-V curve is presented in the form of ln(I) vs V. But I want to know the dV/d(ln(I)) vs I, in order to extract the barrier height. How do I get the data of dV/d(ln(I))? Thanks in advance.
Hi shijun, u can try using matlab, igor or data software like excel to differentiate the data? I believe there are existing functions to differentiate data sets easily. If u are looking at a specific point of curve to find the gradient, u have to use one of the methods like N-R or midpoint algorithm to find the slope.
Hi. There is no need to calculate the derivative. If you know the analytic form of the function to be fitted, least squares method can be used to find all the parameters in the diode equation. This method is implemented in many plotting programs, like gnuplot, igor, origin, etc. You can also find it in many c++/fortran libraries.
@Hashina, yes, there is a built-in function named "diff" which can be used to have differentiation calculation of data. However, It is a rough approximation and the result is not the one i expect. Similar methods in Excel failed as well.
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