Thin film epitaxy and near bulk semiconductor to metal transition in VO2/NiO/YSZ/Si(001) heterostructures

We have grown VO2/NiO epitaxial thin films by pulsed laser deposition where integration with Si(001) substrates was achieved by cubic yttria-stabilized zirconia (YSZ) buffer layer. The most interesting aspect of this work is that a complete relaxation along c-axis of VO2 is achieved in these large misfit systems through the domain matching epitaxy paradigm, which is critical for controlling the semiconductor to metal transition (SMT) characteristics. Regarding x-ray diffraction and cross-sectional transmission electron microscopy results, the epitaxial relationship across the YSZ/Si(001) interface was (001)[100]YSZ‖(001)[100]Si. In the case of YSZ/NiO interface, the epitaxial relationship was $(001)[010]_{{\rm{YSZ}}} \parallel (111)[00\overline 1 ]_{{\rm{NiO}}} $. The epitaxial relationship at the NiO/VO2 interface was determined to be $(010)[001]_{{\rm{VO2}}} \parallel (111)[00\overline 1 ]_{{\rm{NiO}}} $. The SMT characteristics of these fully relaxed films were determined, and a transition temperature of 341 K with amplitude over four orders of magnitude and the hysteresis of 3.4 K hysteresis were obtained, which are close to those of the bulk high quality single crystals.