Investigation of the RF plasma jet system for deposition of LiCoOx thin films

The RF plasma jet system was investigated as a source for the sputtered deposition of LiCoOx thin films. As preliminary results of experiments, LiCoOx films with hexagonal high temperature structure were deposited. The RF hollow cathode in the shape of the cylindrical nozzle was sintered from powder of LiCoO2. This hollow cathode was reactively sputtered in Ar+O2. Plasma jet parameters were investigated during the sputtering process by a Langmuir probe system in the position of the substrate. The electron energy distribution function (EEDF) deviated from the Maxwellian distribution mainly in the energetic range below 5 eV. For higher energies above this value, the EEDF could be approximated with a Maxwellian fit in the limited interval of energies. Obtained electron concentrations were in the range ne=109–6×1010 cm−3 and were strongly dependent on the magnitude of the applied RF power PRF. Electron temperature Teh describing only the limited energy part of EEDF was calculated from this Maxwellian fit and the dependence of Teh on PRF is discussed. Besides XRD, deposited films were investigated by electron microprobe system, scanning electron microscopy and cyclic voltammetry.