Metal-insulator phase transition in Hf-doped VO₂(M) thin films: a study on the structural, electrical, optical and infrared radiation properties

Abstract

In this work, Hf-doped VO2 thin films were fabricated using pulsed laser deposition. We found samples with Hf doping concentrations of 0-3 at.% showed monoclinic VO2(M) phase. When Hf doping concentration increased up to 5-8 at.%, the VO2(M) phase disappeared, and the samples showed a change to VO2(B) structure. Metal-insulator transition (MIT) properties were observed for Hf doping concentration up to 3 at.%. We observed a significant reduction of the phase transition hysteresis width with Hf doping. The temperature-electrical resistance hysteresis curves during MIT show widths of 1.9 °C and 2.7 °C for 1 at.% and 3 at.% Hf-doped VO2 thin films, compared to that of 8.3 °C for pure VO2 thin films. Temperature dependent optical transmittance of Hf doped VO2 thin films also shows similar reduction of phase transition hysteresis width, consistent with the resistance change. Raman spectra revealed significant change in the vibrational intensity of Ag phonon modes that depended also on MIT of thin films and had almost no hysteresis upon Hf doping. Finally, the thermal infrared radiation of Hf-doped VO2(M) thin films was investigated. The hysteretic behavior of the radiation temperature is significantly reduced, making Hf:VO2 a promising candidate for infrared camouflage and thermal radiation control applications.