Compensation of decreased ion energy by increased hydrogen dilution in plasma deposition of thin film silicon solar cells at low substrate temperatures

In order to deposit thin film silicon solar cells on plastics and papers, the deposition process needs to be adapted for low deposition temperatures. In a very high frequency plasma-enhanced chemical vapor deposition (VHF PECVD) process, both the gas phase and the surface processes are affected by low process temperature. Using an electrostatic ion energy analyzer the effect of deposition temperature on the energies of ions reaching the substrate was measured. The ion energy decreases with decreasing temperature, but this can be compensated by diluting the silane source gas by hydrogen.