1. Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Physics and Optoelectronic Engineering, Shenzhen University, 518060 Shenzhen, P. R. China
2. Institute of Materials for Electronics and Magnetism, IMEM-CNR, I-43124 Parma, Italy
3. Physics Department, Taras Shevchenko National University of Kyiv, 01601 Kyiv, Ukraine
4. Center for Advanced Material Diagnostic Technology, College of Engineering Physics, Shenzhen Technology University, 518118 Shenzhen, P. R. China