The Reliability of Measurements on Electron Energy Distribution Function in Silane rf Glow Discharges

AbstractElectron energy distribution function (EEDF) is directly proportional to the second derivative of the probeI-Vcharacteristics. Because of an amplifying effect of unavoidable noises in the experimental probeI-Vcurves on the derivation process, the experimentalI-Vcurves should be smoothed before performing the numerical derivation. This article investigates the effect of adjustable factors used in the smoothing process on the deduced second derivative of theI-Vcurves, and an optimum group of the adjustable factors is selected to make the rms deviation of the smoothedI-Vcurves from the measured ones less than 1 %. A simple differentiation circuit is designed and used to measure the EEDF parameter straightforwardly. It is the first time, so far as we know, to measure the EEDF parameters simultaneously by means of both numerical and circuit derivative methods under the same discharge conditions and on the same discharge equipment. The deviation between two groups of mean electron energy (E) and electron density (ne) obtained by the above different methods is within about 7 %. This apparently improves the reliability of the measurements on the EEDF parameters.