Fig. 4: Transport characteristics of heterostructures as a function of spacer layer thickness.

Schematic representation of quantum mechanical tunneling of charge carrier across the spacer layer for a 2 nm and b 4 nm thicknesses of LAO (t_LAO). ‘Ψ’ is the electronic wave function. The schematics represent a decrease in the transfer of charge carriers from the dopant layer (TiO_2-x layer) to the VO₂ layer as a function of increasing t_LAO. c Resistance-Temperature plots comparing the MIT characteristics of 7.5 nm VO₂ modulation-doped heterostructures employing t_LAO of 2 nm, 4 nm, and 10 nm with the MIT characteristics of a 7.5 nm VO₂ film with a 2 nm LAO cap layer, but without any dopant layer.