Characteristics of a-SiC:H/a-SiGe:H/a-Si:H Thin Film Solar Cells Enhanced by CH₄ Flow Rates Controlling in P-Layer

Abstract

We fabricated a a-SiC:H / a-SiGe:H / a-Si:H thin film solar cell by adjusting CH₄ flow rate in order to absorb long wavelength of solar spectrum without stacked structures such as triple junctions. The a-SiC:H, a-SiGe:H and a-Si:H layers with sheet resistance 7∼8 ohm/sq were deposited on indium tin oxide (ITO) glass by 13.56 MHz radical-assisted plasma-enhanced chemical vapor deposition (RA-PECVD). The working pressure and substrate temperature were 750 mTorr and 250°C, respectively. The a-SiC:H films for p-layer thickness of 300 Å were deposited using 10% CH₄ diluted in H₂. The thickness of a-SiGe:H for i-layer corresponded to 2000 Å. The n-layer was fabricated using 1% PH₃ in diluted H₂. The optical properties of these films were measured by UV-VIS spectrophotometer. The thickness of the film was estimated by FE-SEM were observation. The various values of Jsc, Voc, FF and conversion efficiency were evaluated by the solar simulator.

Keywords:

• a-SiC:H
• a-SiGe:H
• thin-film solar cells
• PECVD
• amorphous silicon

Funding

This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (2012R1A1A2007685), and the Kyungpook National University Research Fund, 2012.