| Hydrogenated nanocrystalline silicon (nc-Si:H) thin films is a kind of silicon nanostructure materials that nanometer silicon grains are embedded in hydrogenated amorphous silicon (a-Si:H) network. It has excellent photoelectric properties like high electrical conductivity, wide bandgap, high absorption coefficient, photoluminescence etc., which has already attracted lots of attention in academic field. On the one hand, as nc-Si:H thin films material has quantum confinement effect, the film wide bandgap can be adjusted by controlling the size of the grain in the thin film to be applied to absorb light of different wavelengths. On the other hand, the excellent light stability of nc-Si:H thin films material without evident S-W effect might be applied in the large scale industrialization production of thin film solar cells.However, the structural and electrical properties of nc-Si:H thin film strongly depends on process parameters. Therefore, in this paper, we present a systematic discussion on the influence of the process parameters (Rf deposition power, hydrogen dilution ratio, deposition temperature and the doping ratio of phosphorus and boron) on the crystallization characteristics, conductivity and growth rate of intrinsic and doped nc-Si:H thin films prepared by PECVD technique. The results show that:(1) Within the certain range, as the RF power increases, all of the crystallization rate of intrinsic and doped nc-Si:H film, the grain size, deposition rate and electrical conductivity increases. But excessive RF power will make the surface of the thin film bombarded by numerous atoms, which makes the electrical conductivity decreases.(2) Improving the hydrogen dilution ratio is the most effective method of depositing nc-Si:H thin film. As the increase of hydrogen dilution ratio, the thin film changes from amorphous silicon to nanocrystalline silicon gradually. Besides, as there is more hydrogen dilution, the degree of crystallization is higher, but the deposition rate of the thin film decreases significantly. (3) During the certain range, improving the deposition temperature will increase the crystallization degree and electrical conductivity of n-type and intrinsic nc-Si:H thin film but decrease those of p-type nc-Si:H thin film, mainly because of the boron doped nc-Si:H thin film easier by dehydrogenation under high temperature. (4) As the doping rate of phosphorus and boron increases, the crystallization degree of thin film decreases, but deposition rate increases. Within the certain range, as the doping rate of phosphorus is higher, the electrical conductivity of thin film is better; however, as the doping rate of boron is higher, the electrical conductivity of thin film is worse, what is more, when the doping rate of phosphorus and boron is higher than 0.5%, the thin film will become amorphous silicon. At last, choosing the best process parameters, preliminarily exploring the application of nc-Si:H thin film in the pin type solar cells, the best efficiency of 4.97% is achieved in the p-i-n type solar cells.AIC is also one of the common methods of depositing nanocrystalline silicon or SiNWs. This paper uses the methods of PECVD and MSD to depositing Sn catalyzed SiNWs. As the SEM pictures shows, the density and uniformity of Sn-SiNWs deposited by PECVD is much higher than those by MSD. Finally, the growth mechanism of SiNWs is discussed with the experiment data. What should be pointed out is that it is the first time to depositing Sn-SiNWs by MSD, which has the potential application prospects in microelectronic devices such as nanoscale sensors, memory etc. Besides, there need to further research about how to control the SiNWs growth in the same direction effectively. |
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