title: Wafer-scale growth of VO2 thin films using a combinatorial approach.
abstract: Transition metal oxides offer functional properties beyond conventional semiconductors. Bridging the gap between the fundamental research frontier in oxide electronics and their realization in commercial devices demands a wafer-scale growth approach for high-quality transition metal oxide thin films. Such a method requires excellent control over the transition metal valence state to avoid performance deterioration, which has been proved challenging. Here we present a scalable growth approach that enables a precise valence state control. By creating an oxygen activity gradient across the wafer, a continuous valence state library is established to directly identify the optimal growth condition. Single-crystalline VO2 thin films have been grown on wafer scale, exhibiting more than four orders of magnitude change in resistivity across the metal-to-insulator transition. It is demonstrated that 'electronic grade' transition metal oxide films can be realized on a large scale using a combinatorial growth approach, which can be extended to other multivalent oxide systems.
authors.affiliation: Department of Materials Science and Engineering and Materials Research Institute, Pennsylvania State University, University Park, Pennsylvania 16802, USA.
authors.forename: Hai-Tian
authors.initials: HT
authors.lastname: Zhang
authors.affiliation: Department of Materials Science and Engineering and Materials Research Institute, Pennsylvania State University, University Park, Pennsylvania 16802, USA.
authors.forename: Lei
authors.initials: L
authors.lastname: Zhang
authors.affiliation: Department of Materials Science and Engineering and Materials Research Institute, Pennsylvania State University, University Park, Pennsylvania 16802, USA.
authors.forename: Debangshu
authors.initials: D
authors.lastname: Mukherjee
authors.affiliation: Department of Physics, Pennsylvania State University, University Park, Pennsylvania 16802, USA.
authors.forename: Yuan-Xia
authors.initials: YX
authors.lastname: Zheng
authors.affiliation: Department of Materials Science and Engineering and Materials Research Institute, Pennsylvania State University, University Park, Pennsylvania 16802, USA.
authors.forename: Ryan C
authors.initials: RC
authors.lastname: Haislmaier
authors.affiliation: Department of Materials Science and Engineering and Materials Research Institute, Pennsylvania State University, University Park, Pennsylvania 16802, USA.
authors.forename: Nasim
authors.initials: N
authors.lastname: Alem
authors.affiliation: Department of Materials Science and Engineering and Materials Research Institute, Pennsylvania State University, University Park, Pennsylvania 16802, USA.
authors.forename: Roman
authors.initials: R
authors.lastname: Engel-Herbert