Taha Mohammad, Walia Sumeet, Ahmed Taimur, Headland Daniel, Withayachumnankul Withawat, Sriram Sharath, Bhaskaran Madhu
Functional Materials and Microsystems Research Group and Micro Nano Research Facility, RMIT University, Melbourne, Victoria, 3001, Australia.
School of Electrical and Electronic Engineering, The University of Adelaide, South Australia, 5005, Australia.
Sci Rep. 2017 Dec 20;7(1):17899. doi: 10.1038/s41598-017-17937-3.
Vanadium has 11 oxide phases, with the binary VO presenting stimuli-dependent phase transitions that manifest as switchable electronic and optical features. An elevated temperature induces an insulator-to-metal transition (IMT) as the crystal reorients from a monoclinic state (insulator) to a tetragonal arrangement (metallic). This transition is accompanied by a simultaneous change in optical properties making VO a versatile optoelectronic material. However, its deployment in scalable devices suffers because of the requirement of specialised substrates to retain the functionality of the material. Sensitivity to oxygen concentration and larger-scale VO synthesis have also been standing issues in VO fabrication. Here, we address these major challenges in harnessing the functionality in VO by demonstrating an approach that enables crystalline, switchable VO on any substrate. Glass, silicon, and quartz are used as model platforms to show the effectiveness of the process. Temperature-dependent electrical and optical characterisation is used demonstrating three to four orders of magnitude in resistive switching, >60% chromic discrimination at infrared wavelengths, and terahertz property extraction. This capability will significantly broaden the horizon of applications that have been envisioned but remained unrealised due to the lack of ability to realise VO on any substrate, thereby exploiting its untapped potential.
钒有11种氧化物相，二元VO呈现出依赖于刺激的相变，表现为可切换的电子和光学特性。温度升高会引发绝缘体到金属的转变（IMT），此时晶体从单斜晶态（绝缘体）重新取向为四方排列（金属态）。这种转变伴随着光学性质的同时变化，使VO成为一种多功能的光电子材料。然而，由于需要特殊的衬底来保持材料的功能，其在可扩展器件中的应用受到了限制。对氧浓度的敏感性以及更大规模的VO合成也是VO制造中一直存在的问题。在此，我们通过展示一种在任何衬底上实现结晶、可切换VO的方法，解决了利用VO功能方面的这些主要挑战。玻璃、硅和石英被用作模型平台来展示该工艺的有效性。通过对温度依赖的电学和光学表征，展示了电阻切换中三到四个数量级的变化、红外波长下>60%的色度辨别以及太赫兹特性提取。这种能力将显著拓宽由于缺乏在任何衬底上实现VO的能力而一直设想但未实现的应用范围，从而挖掘其未开发的潜力。
