Harnessing Multifractality to Enhance Thermal Stability in Mixed-Phase Vanadium Oxide Thin Films

Abstract

Vanadium oxide thin films exhibit temperature-driven electronic transitions desirable for sensing and microelectronic applications, yet their performance is often limited by thermal hysteresis. This study demonstrates that electronic stability is governed not simply by roughness or crystallinity but by a unique combination of surface morphological complexity and thermal hysteresis, revealed across films deposited with varying working pressure using Direct Current/Radio Frequency magnetron sputtering. Specifically, the film grown at 15 mTorr shows a distinct convergence of highest morphological vertical complexity and lowest thermal hysteresis, exhibiting nearly reversible transport with activation energies ranging from 0.26 to 0.28 eV and negative temperature coefficients of resistance between -0.0337 and -0.035 K-1. While conventional roughness metrics and mono-fractal parameters do not capture this behavior, multifractal detrended fluctuation analysis uncovers a pronounced peak in multifractality strength, which correlates inversely with thermal hysteresis. This highlights multifractality strength as a predictive descriptor of electronic stability, identifying a multiscale structural signature that enhances stress accommodation during thermal cycling. These results define an optimal deposition window and provide a morphology-guided pathway for developing thermally robust mixed-phase vanadium oxide films.