1. Engineering Research Center of Electronic Information Materials and Devices, Ministry of Education, Guilin University of Electronic Technology, Guilin 541004, P. R. China
2. Guangxi CNGR New Energy Science & Technology Co., Ltd., Qinzhou 535000, P. R. China
3. Karlsruhe Institute of Technology, Institute for Applied Materials – Applied Materials Physics, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
4. State Key Laboratory of Powder Metallurgy, Central South University, Changsha, Hunan, 410083, China