Control of Polymorphic Properties of Multivalent Vanadium Oxide Thin Films

• Published in: ACS applied electronic materials Vol. 3; no. 3; pp. 1142 - 1150
• Main Authors: Allabergenov, Bunyod, Yun, Sanghun, Cho, Hui-Sup, Lyu, Hong-Kun, Choi, Byeongdae
• Format: Journal Article
• Language: English
• Published: American Chemical Society 23-03-2021
• Subjects: multivalent vanadium oxides; phase transitions; electro-optical thermochromic thin films; DC magnetron sputtering; slope stiffness
• ISSN: 2637-6113; 2637-6113
• DOI: 10.1021/acsaelm.0c01010

In this study, V x O y thin films were deposited on borosilicate glass substrates using direct current (DC) magnetron sputtering. The optoelectronic thermochromic properties of the resulting multiphase vanadium oxide thin films were investigated. As-deposited (at 280 °C) films were annealed at 350, 450, and 500 °C in an oxygen atmosphere for 30 min in a tube furnace to improve the crystallinity. Structural analysis indicated the formation of a mixed-phase vanadium oxide film consisting of VO2(B), V4O9, and V2O5 phases on the amorphous substrate after annealing above 350 °C. The results showed that the semiconductor-to-metallic phase transition temperature of the vanadium oxide film increased from 48 to 63 °C with increasing annealing temperatures. The sample annealed at 450 °C exhibited the highest variation in the infrared (IR) transmittance (ΔT IR = 28.42%) and the resistivity switch decreased by two orders of magnitude (1.4 × 10–1–2.3 × 10–3 Ω/cm). The thermal treatment temperature affected the width of the thermal hysteresis loop (H LW) and slope stiffness. A narrower H LW of 1.9 °C and a sharp slope stiffness of 8.74 were obtained for the sample annealed at 500 °C. The slope stiffness plays an important role in the fabrication of ultrafast tunable energy-saving smart windows and IR switches.