Characteristics of Amorphous Silicon Thin-Film Solar Cells of a-Si:H/a-SiGe:H Superlattices in Different Thickness for Barrier and Well Layers

Amorphous silicon (a-Si:H)/amorphous silicon-germanium (a-SiGe:H) superlattices were deposited by 13.56 MHz plasma enhanced chemical vapor deposition (PECVD) method using a mixture of SiH4, GeH4and H2. 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 (2–10 nm). 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 (Voc), short-circuit current density (Jsc), and conversion efficiency were measured under 100 mW/cm2(AM 1.5) solar simulator irradiation. In the fabricated structure, we achieved a higher conversion efficiency (η = 4.52%) than general a-Si:H solar cell (η = 2.10%) and a-SiGe:H solar cell (η = 3.06%).