Korean Institute of Surface Engineering

pISSN : 1225-8024 | eISSN : 3399-8403

공학

한국표면공학회지 (50권3호 141-146)

Nanoscopic Understanding of Phase Transition of Epitaxial VO2 Thin Films

에피택셜 VO2 박막의 상전이에 대한 미시적 이해

김동욱;손아름;
Kim, Dong-Wook;Sohn, Ahrum;

이화여자대학교 물리학과;성균관대학교 신소재공학부;
Department of Physics, Ewha Womans University;School of Advanced Materials Science & Engineering, Sungkyunkwan University;

DOI : 10.5695/JKISE.2017.50.3.141

Abstract

We investigated configuration of metallic and insulating domains in $VO_2$ thin films, while spanning metal-insulator phase transition. Kelvin probe force microscopy, of which spatial resolution is less than 100 nm, enables us to measure local work function (WF) at the sample surface. The WF of $VO_2$ thin films decreased (increased) as increasing (decreasing) the sample temperature, during the phase transition. The higher and lower WF regions corresponded to the insulating and metallic domains, respectively. The metallic fraction, estimated from the WF maps, well explained the temperature-dependent resistivity based on the percolation model. The WF mapping also showed us how the structural defects affected the phase transition behaviors.

Keywords

$VO_2$;Phase transition;Work function;Kelvin probe microscopy;Percolation;Structural defects;