Microcrystalline silicon thin-film solar cells prepared at low temperature using RF-PECVD

Hydrogenated microcrystalline silicon (μc-Si:H) p-i-n solar cells have been prepared using a conventional RF-plasma-enhanced chemical vapor deposition (PECVD) method at a low process temperature of 140°C. Low temperature deposition is effective to suppress the formation of oxygen-related donors that cause a reduction in open circuit voltage (Voc) by shunt leakage. We demonstrate the improvement of Voc by lowering the deposition temperature down to 140°C with maintaining high short circuit current density (Jsc) and fill factor (FF). An efficiency of 8.9% was obtained using an Aasahi-U substrate. Further optimization of texture of transparent conductive oxide (TCO) substrate has been developed by using ZnO, and the highest efficiency of 9.4% (Voc=0.526 V, Jsc=25.3 mA/cm^-1, FF-0.710) in our study was obtained on ZnO substrate textured by etching process. Limiting factors of solar cell performance are discussed based on the growth mechanism of μc-Si:H