Electrically Controlled Metal-Insulator Transition and Its Terahertz Applications

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Overview: We propose to investigate dramatic changes in electronic and photonicproperties of new functional devices based on the reversible metal-insulator transition(MIT) of vanadium dioxide. The electrical resistivity of VO2 changes by 4 to 5 orders.Variations in refractive index exceed 15%, giving an index contrast of greater than 3relative to free space. This unique combination of properties motivates the study of itsphase transition mechanisms, control of its properties, and development of terahertz(THz) functional components.Intellectual Merit: We will explore the fundamental physics of VO2 phase transition,particularly when driven electrically in pulsed current mode or in gate electric-field mode,and develop new functional devices for THz switching and modulation applications withthe aim of reconfigurable manipulation. Through the study of phase transitionmechanisms and factors to influence the transition ?speed? we will engineer the materialstructure to achieve abrupt ?digital? switching and controllable percolative phasetransition for ?analog? modulation. The result will provide fundamental understanding ofelectrically controlled metal-insulator transition and promote the application of phasetransition-based materials for electronic and photonic applications.Broader Impact: Study of phase transitions will provide new opportunities to achieveinnovative functional devices. These devices will exhibit unprecedented operationalprinciples for electronic and photonic applications, in addition to fundamental scientificunderstanding. The proposed components will find broad applications in THz technology.The project provides excellent opportunities for interdisciplinary research education andtraining. Outreach efforts will attract new students, especially those fromunderrepresented groups, to science and engineering fields.