A study of intrinsic amorphous silicon thin film deposited on flexible polymer substrates by magnetron sputtering

• Amorphous silicon thin films were deposited on PET substrate.
• Experimental parameters were systematically investigated.
• Deposition rate on PET increased remarkably with sputtering power.
• Different processing parameters affect the deposition rate of amorphous silicon significantly.
• Absorption coefficient of thin films reduced with wavelength.

Amorphous silicon (a-Si) has gained its popularity in thin film solar cell fabrication for its high absorption coefficient, high applicability on flexible substrates and practical feasibility for low-cost roll-to-roll mass fabrication. Working as the intrinsic layer, the optical-electrical characteristics of amorphous silicon film is crucial to the cell performance. In this work, the amorphous silicon film has been fabricated on PET substrate by magnetron sputtering method. The main optical-electrical characteristics have been systematically investigated under different fabrication conditions (sputtering power, working pressure, working temperature). The results indicate that the deposition rate increases remarkably from 1.88 to 8.74 nm/min with the sputtering power increasing from 60 W to 120 W, while the light transmission rate decreases from 86% to 46% in the visible spectrum range (390 nm to 780 nm). Theoretical calculations have been carried out, showing a decreasing deposition rate under an increasing working pressure. A rising temperature provides a higher deposition rate and lower transmittance in the certain range. The optimized processing parameters in the fabrication of amorphous silicon thin film are obtained for high photoelectric property on flexible substrates.