Plasma deposition of amorphous free microcrystalline silicon films thinner than 20 nm

Highly crystallized, thin p-type silicon films are deposited by very high frequency plasma-enhanced CVD. Under high H2 dilution conditions, the effect of chamber contamination is shown to have consequencies on the microcrystalline (mc) fraction and electrical characteristics of the deposited films. In view of applications on heterojunction solar cells, p/i double layers are deposited on silicon and on glass. Optical characterisation shows that the mc fraction is much larger on silicon substrate. A 15 nm amorphous buffer layer deposited on silicon is observed to completely recrystallize upon p-type mc-Si deposition, which is attributed to the effect of undetectable crystalline seeds in the amorphous phase.