The properties of hydrogenated microcrystalline silicon thin films, including structure, optical and electrical properties, are investigated first in order to choose the proper HWCVD deposition parameters for solar cell fabrications in this thesis. Then microcrystalline silicon solar cells are fabricated, and in order to increase the open-circuit voltage of solar cells, heavily doping amorphous silicon are used as n+ and p+ layers. Besides, the fabrication and characteristics of amorphous silicon solar cells are also investigated, and the external quantum efficiency of amorphous and microcrystalline silicon solar cells are compared. Finally, in order to obtain much higher open-circuit voltage and wider light absorption spectra, the micromorph tandem solar cell is fabricated. The open-circuit voltage of the tandem solar cell achieved is 950 mV with wider absorption spectra comparing to single junction a-Si:H solar cell and total efficiency is 2.70%.