Cheng Xiankun, Gao Qiang, Li Kaifeng, Liu Zhongliang, Liu Qinzhuang, Liu Qiangchun, Zhang Yongxing, Li Bing
School of Physics and Electronic Information, Huaibei Normal University, Huaibei 235000, China.
Nanomaterials (Basel). 2019 Jul 24;9(8):1061. doi: 10.3390/nano9081061.
For growing high quality epitaxial VO thin films, the substrate with suitable lattice parameters is very important if considering the lattice matching. In addition, the thermal conductivity between the substrate and epitaxial film should be also considered. Interestingly, the c-plane of hexagonal 6H-SiC with high thermal conductivity has a similar lattice structure to the VO (010), which enables epitaxial growth of high quality VO films on 6H-SiC substrates. In the current study, we deposited VO thin films directly on 6H-SiC (0001) single-crystal substrates by pulsed laser deposition (PLD) and systematically investigated the crystal structures and surface morphologies of the films as the function of growth temperature and film thickness. With optimized conditions, the obtained epitaxial VO film showed pure monoclinic phase structure and excellent phase transition properties. Across the phase transition from monoclinic structure (M1) to tetragonal rutile structure (R), the VO/6H-SiC (0001) film demonstrated a sharp resistance change up to five orders of magnitude and a narrow hysteresis width of only 3.3 °C.
对于生长高质量的外延VO薄膜，如果考虑晶格匹配，具有合适晶格参数的衬底非常重要。此外，还应考虑衬底与外延膜之间的热导率。有趣的是，具有高导热率的六方6H-SiC的c平面具有与VO(010)相似的晶格结构，这使得高质量的VO薄膜能够在6H-SiC衬底上外延生长。在本研究中，我们通过脉冲激光沉积(PLD)直接在6H-SiC(0001)单晶衬底上沉积VO薄膜，并系统地研究了薄膜的晶体结构和表面形貌随生长温度和薄膜厚度的变化。在优化条件下，获得的外延VO薄膜呈现出纯单斜相结构和优异的相变特性。在从单斜结构(M1)到四方金红石结构(R)的相变过程中，VO/6H-SiC(0001)薄膜表现出高达五个数量级的急剧电阻变化和仅3.3℃的窄滞后宽度。
