A method of fabricating a solar cell includes: forming a first electrode on a substrate; forming a first impurity-doped semiconductor layer on the first electrode; forming a first intrinsic semiconductor layer of amorphous silicon on the first impurity-doped semiconductor layer; forming a second impurity-doped semiconductor layer over the first impurity-doped semiconductor layer, forming a second electrode over the second impurity-doped semiconductor layer; and irradiating a first microwave to form a second intrinsic semiconductor layer of microcrystalline silicon by crystallizing the first intrinsic semiconductor layer.