3 Debye screening

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The most obvious difference between the 'exact' and approximate solutions is in the density plots. In the approximate solution the electron and hole densities are assumed to drop instantaneously from the bulk value to zero on entering the depletion region. What is the 'exact' behavior? Select 'exact' from the solution menu.

To get a quantitative picture, copy densities, click on configure in the copied graph and select the YLog toggle. Focus your attention on the log(rho) plot in the n-region, which is the difference between the donor and electron concentrations. Zoom on the left hand portion of the plot to capture the region in which the log(rho) plot is linear. The linearity of this plot for four orders of magnitude in charge density demonstrates the exponential character of the screening for potential variations of magnitude small compared to kT/e. This screening is referred to as Debye screening.