[1] Nantong Univ, Sch Microelect, Nantong 226019, Peoples R China
[2] Nantong Univ, Sch Integrated Circuits, Sch Informat Sci & Technol, Nantong 226019, Peoples R China
[3] City Univ Hong Kong, Dept Mat Sci & Engn, Hong Kong 999077, Peoples R China
[4] City Univ Hong Kong, State Key Lab Terahertz & Millimeter Waves, Hong Kong 999077, Peoples R China
[5] Univ Colorado, Dept Phys, Boulder, CO 80309 USA
[6] Univ Colorado, JILA, Boulder, CO 80309 USA
[7] East China Normal Univ, Sch Phys & Elect Sci, Shanghai 200241, Peoples R China