Secondary electron energy spectra emitted from radio frequency biased plasma electrodes

The ion-induced secondary electron energy spectra from a radio frequency biased (13.56 MHz) electrically insulating (Al2O3) plasma electrode surface immersed in a separately powered inductively coupled plasma are studied both experimentally and theoretically. Radio frequency (rf) electrode bias voltages of 140 and 285 V (peak to ground) are employed and the complete electron energy spectra emitted from the electrode and accelerated by the rf sheath are measured 14 cm from the rf biased electrode using a differentially pumped retarding potential analyzer. A collisionless radio frequency Child–Langmuir sheath model is used to explain the experimentally measured electron energy spectra.