1. Laboratory for Terahertz Research, Tomsk State University, 634050 Tomsk, Russia
2. Synchrotron Radiation Detector Laboratory, R&D Center “Advanced Electronic Technologies”, Tomsk State University, 634050 Tomsk, Russia
3. Department of Semiconductor Physics, Tomsk State University, 634050 Tomsk, Russia
4. Department of Physics, Chemistry and Theoretical Mechanics, Tomsk State University of Architecture and Building, 634003 Tomsk, Russia
5. School of Physical Science and Engineering, Beijing Jiaotong University, Beijing 100044, China