Improved measurement method for electron energy distribution functions with high accuracy and reliability

An improved ac superimposed method for measuring the electron energy distribution function (EEDF) with high accuracy is proposed. Although high amplitude of the superimposed ac voltage provides a higher signal-to-noise ratio (SNR), it causes the distortion in the EEDF. To correct the distortion, we used two different EEDFs measured by applying two different amplitudes. The distortion was accurately corrected over the entire electron energy region, and the corrected EEDF had the better SNR. The reliability of the corrected EEDF was proved by comparing the effective electron temperatures obtained from the measured EEDFs, and as a result, the corrected EEDF was very reliable.