Baojun Yan, Shulin Liu, Lei Zhao, Wenjing Wang, Yuzhen Yang, "Influence of band gap grading of intrinsic layer and annealing post on the optical and electrical performance of amorphous silicon germanium thin film solar cells," Proc. SPIE 9284, 7th International Symposium on Advanced Optical Manufacturing and Testing Technologies: Optoelectronics Materials and Devices for Sensing and Imaging, 92840A (2 September 2014);