Amorphous silicon (a-Si:H)/amorphous silicon-germanium (a-SiGe:H) superlattices were deposited by 13.56MHz plasma enhanced chemical vapor deposition (PECVD) method using a mixture of SiH4, GeH(4)and H-2. The superlattice materials consist of alternating layers of a-Si:H and a-SiGe:H. The a-Si:H layers were used as barrier material and a-SiGe:H layers were used as well material. It was found that the optical bandgap was controlled by changing the thickness of the barrier layer of a-Si:H (2-10nm). Based on these results, fabricated the pin-type a-Si:H based solar cells of superlattice structures in different thickness for barrier and well layers. The various values of open-circuit voltage (V-oc), short-circuit current density (J(sc)), and conversion efficiency were measured under 100 mW/cm(2)(AM 1.5) solar simulator irradiation. In the fabricated structure, we achieved a higher conversion efficiency ( = 4.52%) than general a-Si:H solar cell ( = 2.10%) and a-SiGe:H solar cell ( = 3.06%).