Effect of Plasma Radical Composition in Intrinsic a-Si:H on Performances of Heterojunction Solar Cells

In this paper, intrinsic hydrogenated amorphous silicon films are prepared by plasma enhanced chemical vapor deposition. The plasma spectra obtained by an optical emission spectroscopy at different deposition regions are analyzed. By comparing these spectra, the nonuniform deposition regions that could significantly limit the solar cell performance can be found. Tilting the substrate with a certain angle can adjust the electrode-to-substrate distance at the required regions so that the uniformity can be improved. In the case of our experiment, a substrate tilt angle of 1.5° results in a uniformity of within ±8% and a 156 × 156-mm ² heterojunction solar cell with conversion efficiency of 18.55% that is improved by 11% compared with the cell without substrate tilting.