A Novel Method for Notable Reducing Phase Transition Temperature of VO2 Films for Smart Energy Efficient Windows.

Huan Guan,Qicong He,Dongping Zhang,Yi Liu,Aihua Zhong,Jiahua Qi,Yu Yang,Ping Fan

doi:10.3390/nano10010058

Abstract

Although Vanadium dioxide (VO2) has a potential application value for smart energy efficient windows because of its unique phase transition characteristic, there are still many obstacles that need to be overcome. One challenge is to reduce its high transition temperature (ζc = 68 °C) to near room temperature without causing its phase transition performance degradation. In this paper, a novel method was employed that covered a 3 nm ultra-thin heavy Cr-doped VO2 layer on the pure VO2 films. Compared with the as-grown pure VO2, obviously, phase transition temperature decreasing from 59.5 °C to 48.0 °C was observed. Different from previous doping techniques, almost no phase transition performance weakening occurred. Based on the microstructure and electrical parameters measurement results, the mechanism of ζc reducing was discussed. The upper ultra-thin heavy Cr-doped layer may act as the induced role of phase transition. With temperature increasing, carrier concentration increased from the upper heavy Cr-doped layer to the bottom pure VO2 layer by diffusion, and induced the carrier concentration reach to phase transition critical value from top to bottom gradually. The present method is not only a simpler technique, but also avoids expensive alloy targets.

Highlights

IntroductionVanadium dioxide (VO2) is one of the most interesting smart materials for its reversible metal-insulator transition (MIT) near room temperature (ζc = 68 ◦C) [1], in which optical, electrical, and other physical properties (transmittance, reflectance, emittance, refractive index, electrical resistivity etc.) [2,3] will be sharp changed by external stimuli (applied field or voltage [4], incident light [5], temperature variation [6], mechanical stress [7], pressure [8], etc.) in the transition process
Vanadium dioxide (VO2) is one of the most interesting smart materials for its reversible metal-insulator transition (MIT) near room temperature [1], in which optical, electrical, and other physical properties [2,3] will be sharp changed by external stimuli in the transition process
Pure VO2 films were prepared by reactive pulsed magnetron sputtering, and a 3 nm ultra-thin heavy Cr-doped VO2 layer was employed to cover on the prepared pure VO2 film surface

Summary

Introduction

Vanadium dioxide (VO2) is one of the most interesting smart materials for its reversible metal-insulator transition (MIT) near room temperature (ζc = 68 ◦C) [1], in which optical, electrical, and other physical properties (transmittance, reflectance, emittance, refractive index, electrical resistivity etc.) [2,3] will be sharp changed by external stimuli (applied field or voltage [4], incident light [5], temperature variation [6], mechanical stress [7], pressure [8], etc.) in the transition process. The present method is a simpler technique, and avoidsexpensive alloy targets

Experimental Details

Findings

Result and Discussion

Conclusions