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

TL;DR

This paper shows that multifractal analysis of surface morphology can predict and enhance the thermal stability of vanadium oxide thin films, leading to more reliable electronic applications.

Contribution

It introduces multifractal detrended fluctuation analysis as a novel predictor of thermal hysteresis in vanadium oxide films, linking surface complexity to electronic stability.

Findings

Peak multifractality correlates with lowest thermal hysteresis.

Optimal deposition at 15 mTorr yields highest morphological complexity.

Multifractality strength inversely relates to thermal hysteresis.

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.