MICROSTRUCTURAL PROPERTIES OF NC-Si/SiO2 FILMS IN SITU GROWN BY REACTIVE MAGNETRON CO-SPUTTERING

Nanocrystalline silicon embedded in silicon oxide (nc-Si/SiO2) films have been in situ grown at a low substrate temperature of 300 degrees C by reactive magnetron co-sputtering of Si and SiO2 targets in a mixed Ar/H-2 discharge. The influences of H-2 flow rate (FH) on the microstructural properties of the deposited nc-Si/SiO2 films were investigated. The results of XRD and the deposition rate of nc-Si/SiO2 films show that the introduction of H-2 contributes to the growth of nc-Si grains in silicon oxide matrix. With further increasing FH, the average size of nc-Si grains increases and the deposition rate of nc-Si/SiO2 films decreases gradually. Fourier transform infrared spectra analyses reveal that introduction of hydrogen contributes to the phase separation of nc-Si and SiOx in the deposited films. Moreover, the Si-O4-nSin (n = 0; 1) concentration of the deposited nc-Si/SiO2 films reduces with the increase of FH, while that of Si-O4-nSin (n = 2,3) concentration increases. These results can be explained by that active hydrogen atoms increase the probability of reducing oxygen from precursor in the plasma and prompting oxygen desorption from the growing surface. This low-temperature procedure for preparing nc-Si/SiO2 films opens up the possibility of fabricating the silicon-based thin-film solar cells onto low-cost glass substrates using nc-Si/SiO2 films.