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Highly efficient terahertz wave modulators by photo-excitation of organics/silicon bilayers

2014; American Institute of Physics; Volume: 105; Issue: 1 Linguagem: Inglês

10.1063/1.4887376

1520-8842

Hyung Keun Yoo, Youngwoon Yoon, Kiejin Lee, Chul Kang, Chul‐Sik Kee, In‐Wook Hwang, Joong Wook Lee,

Semiconductor Quantum Structures and Devices

Using hybrid bilayer systems comprising a molecular organic semiconductor and silicon, we achieve optically controllable active terahertz (THz) modulators that exhibit extremely high modulation efficiencies. A modulation efficiency of 98% is achieved from thermally annealed C60/silicon bilayers, due to the rapid photo-induced electron transfer from the excited states of the silicon onto the C60 layer. Furthermore, we demonstrate the broadband modulation of THz waves. The cut-off condition of the system that is determined by the formation of efficient charge separation by the photo-excitation is highly variable, changing the system from insulating to metallic. The phenomenon enables an extremely high modulation bandwidth and rates of electromagnetic waves of interest. The realization of near-perfect modulation efficiency in THz frequencies opens up the possibilities of utilizing active modulators for THz spectroscopy and communications.