Sharp Phase Transition by the Enhanced Lattice Stability of Low‐Temperature Phase of Cr‐Doped VO2

• Published in: Bulletin of the Korean Chemical Society Vol. 42; no. 9; pp. 1232 - 1238
• Main Authors: Hong, Seong‐Cheol, Lee, Myeongsoon, Lee, Myung Won, Kim, Don
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley‐VCH Verlag GmbH & Co. KGaA 01-09-2021; 대한화학회
• Subjects: Cr‐doping; Phase transition; Smart window; VO2; 화학
• ISSN: 1229-5949; 0253-2964; 1229-5949
• DOI: 10.1002/bkcs.12353

We have prepared Cr‐doped VO2 film (V1−xCrxO2, 0 ≤ x ≤ 0.15) on a c‐cut sapphire plate (0001). The insulator to metal transition (IMT) behavior of the VO2 was observed by the resistance and transmittance measurements near the phase transition point (Tc ~ 340 K). Whereas the starting point of metal to insulator transition (THE) was nearly constant at 350 K (x ≤ 0.03), the starting point of the insulator to metal transition (THS) was shifted from 308 K (x = 0) to 326 K (x = 0.05), suggesting that the Cr‐doped VO2 lattice is significantly stabilized below Tc of the VO2. The difference between THS and THE and the gap between thermal cycles (hysteresis gap), which reflect the sharpness of the phase transition, were minimal at x = 0.03–0.05 in V1−xCrxO2. This sudden phase transition of Cr‐doped VO2 is expected to be uniquely advantageous for sensitive on–off applications.
In this report, we investigated the phase transition of Cr‐doped VO2 films (V1−xCrxO2, 0 ≤ x ≤ 0.15) deposited on the sapphire. The Cr doping stabilized the insulator VO2 lattice. The starting point of insulator to metal transition temperature moved from 308 K (x = 0) to 320 K (x = 0.05). The narrowest transition gap (sharpest transition) was observed in x = 0.03–0.05.