High-quality hydrogenated intrinsic amorphous silicon oxide layers treated by H2 plasma used as the p/i buffer layers in hydrogenated amorphous silicon solar cells

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• High-quality i-a-SiOx:H film has obtained by H2 plasma treatment.
• Origin of property improvement of the i-a-SiOx:H film is stuied.
• FTIR spectroscopy and initial growth of films have been intensively examined.
• Initial conversion efficiency of a-Si:H solar cells can reach to 11.3%.

The treatment of hydrogenated intrinsic amorphous silicon oxide (i-a-SiOx:H) films by H2 plasma is found through Fourier transform infrared (FTIR) spectroscopy to significantly improve the quality of the layers, which is attributed to variation in the Si–Hn bonding structure and an improvement of bonding order. Meanwhile, scanning electron microscopy (SEM) results indicate that the initial growth of a hydrogenated intrinsic amorphous silicon (i-a-Si:H) layer deposited on a treated i-a-SiOx:H film is also improved, which is beneficial to the performance of solar cells deposited on highly textured front electrodes. By inserting an i-a-SiOx:H film that is optimized in terms of H2 plasma treatment time as a p/i buffer layer in hydrogenated amorphous silicon (a-Si:H) solar cell, a significant increase in fill factor and open-circuit voltage are also observed. In this way, a high initial conversion efficiency of 11.3% can be achieved in a single-junction a-Si:H solar cell with an active layer thickness of 300 nm.