Electric-field control of Li-doping induced phase transition in VO2 film with crystal facet-dependence

The use of electric-field to manipulate the transport properties of correlated oxides is promising for achieving nano-functional electronic devices. As a typical correlated oxide material, vanadium dioxide (VO 2 ) displays a special metal-insulator transition (MIT) at about 340 K. In this work, we select a water-free electrolyte gel, Li + /propylene carbonate, to achieve a non-volatile and reversible Li-doping and phase modulation in nano-VO 2 crystal film under gating voltages. Synchrotron characterizations indicate the originally insulating VO 2 undergoes an effective structure change and an increased V 3 d -O 2 p hybrid t 2 g -orbital occupancy, which is responsible for the metallic state formation as proved by first-principle calculation. The field-driving Li-doping shows pronounced facet dependence, indicating the existence of energetically favored channels for Li-ions diffusion along V-V chains as proved by dynamic stimulation. Our current findings will supply opportunities for the electric-field control of atomic sieve, correlated ionitronics and synaptic transistor.