Abstract:
"The present work deals with the study of interaction plasma-substrate effect on
sputtered a-Si :H films growth mechanism. The experimental part was carried by varying two
parameters : the RF power of electric discharge and substrate nature.
The caracterization by scanning electronic microscopy of samples prepared on glass
substrate at substrate temperature of 200°C, revealed a change of the surface morpholy with
the variation of RF power. Indeed, a polycristallization was detected on sample surface
deposited with higher power 400W. This result was confirmed by transmission electronic
microscopy. The infrared spectroscopy (FTIR) showed a decrease of hydrogen content with
increasing RF power. Besides this, an increase of material densification was detected by UV
visible spectroscopy.
On the other hand, the caractrization by SEM of the deposited films on various
substrates with RF power fixed at 400W and substrate temperature at 200°C, showed a light
surface roughness of the film prepared on single-crystalline silicon sustrate. However, the
surface of film deposited on aluminum subtrate remains amorphous.
In order to explain these results, we proceeded to the study of the plasma by three
approaches : i) by calculating the strength generated by the impact of the plasma particules on
the growing film according to pressure and to RF power, ii) by developping a physical model
which allows to calculate the energy distribution of argon ions reaching the substrate, iii) we
have also proposed a numerical model which allows temperature calculation of growing film
with the deposition time.
This study showed that the temperature of growing film is the most controlling
parameter of a-Si :H films growth mechanism."
