Single-Chamber Process for Deposition of Thin-Film Silicon Solar Cells without Plasma Treatment

25th European Photovoltaic Solar Energy Conference and Exhibition / 5th World Conference on Photovoltaic Energy Conversion, 6-10 September 2010, Valencia, Spain; 2978-2982
For the deposition of a-Si:H solar cells, a single-chamber process was developed. A singlechamber fabrication of a-Si:H solar cells in an inline 40 × 40 cm2 deposition system with an initial efficiency of = 10.3 % is achieved. To avoid boron cross-contamination, usually a critical issue for single-chamber processes, reactor treatments prior to the i-layer deposition are required. Three types of treatments are compared for their effectivity and required treatment time, namely a CO2-plasma, a reactor evacuation and a cell deposition without plasma stop. The deposition without plasma-stop did not lead to state-of-the-art solar cell performances. A strong boron cross-contamination leads to losses in conversion efficiency, especially in the short wavelength range. The two other types of treatments led to the deposition of high-quality solar cells. The required treatment time was 15 min and 27 min for chamber evacuation and CO2-plasma treatment, respectively. For the “process chamber evacuation” with the substrate remaining in the recipient (in-situ), subsequent to the deposition of the p-layer the chamber is evacuated to 9×10-7 mbar prior to the deposition of the i-layer. For the device designs applied in this work, the influence on the boron cross-contamination is not significantly different.