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

Hydrogenated microcrystalline silicon ( mu c-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 degreesC. 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 degreesC with maintaining high short circuit current density (Jsc) and fill factor (FF). A 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=0.526V, Jsc=25.3mA/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 mu c-Si:H.