Highly crystallised, 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 consequences on the microcrystalline (µc) fraction and electrical characteristics of the deposited films. In view of applications on heterojunction solar cells, p/i double layers a re deposited on silicon and on glass. Optical characterisation shows that the µc fraction is much larger on silicon substrate. A 15 nm amorphous buffer layer deposited on silicon is observed to completely recrystallise upon p-type µc-Si deposition, which is attributed to the effect of undetectable crystalline seeds in the amorphous phase.