Abstract Monoclinic molybdenum trioxide (β-MoO3) nanostructures (shaped like nanoribbons: NRs) were grown on Si(1 0 0), Si(5 5 1 2) and fluorine-doped tin oxide (FTO) by molecular beam epitaxy (MBE) technique under ultra-high vacuum (UHV) conditions. The dependence of substrate conditions and the effective thickness of MoO3 films on the morphology of nanostructures and their structural aspects were reported. The electron microscopy measurements show that the length and the aspect ratio of nanostructures increased by, 260% without any significant change in the width for a change in effective thickness from 5 nm to 30 nm. NRs are grown along 〈0 1 1〉 for all the effective thickness of MoO3 films. Similarly, when we increased the film thickness from 5 nm to 30 nm, the optical band gap decreased from 3.38 ± 0.01 eV to 3.17 ± 0.01 eV and the local work function increased from 5.397 ± 0.025 eV to 5.757 ± 0.030 eV. Field emission turn-on field decreased from 3.58 V/μm for 10 μA/cm2 to 2.5 V/μm and field enhancement factor increased from 1.1 × 104 to 5.9 × 104 for effective thickness variation of 5–30 nm β-MoO3 structures. The β-MoO3 nanostructures found to be much better than the α-MoO3 nanostructures due to low work function, low turn on field and high field enhancement factor, and are expected to be useful applications.

中文翻译：

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MBE 生长的 β-MoO3 纳米带的光学带隙、局域功函数和场发射特性

摘要 通过分子束外延 (MBE) 在 Si(1 0 0)、Si(5 5 1 2) 和掺氟氧化锡 (FTO) 上生长单斜三氧化钼 (β-MoO3) 纳米结构（形状像纳米带：NRs）超高真空 (UHV) 条件下的技术。报道了基板条件和 MoO3 薄膜的有效厚度对纳米结构形态及其结构方面的依赖性。电子显微镜测量表明，对于有效厚度从 5 nm 到 30 nm 的变化，纳米结构的长度和纵横比增加了 260%，而宽度没有任何显着变化。对于所有有效厚度的 MoO3 薄膜，NRs 都沿 <0 1 1> 生长。同样，当我们将薄膜厚度从 5 nm 增加到 30 nm 时，光学带隙从 3.38 ± 0.01 eV 减小到 3.17 ± 0。01 eV 和局部功函数从 5.397 ± 0.025 eV 增加到 5.757 ± 0.030 eV。对于 5–30 nm β-MoO3 结构的有效厚度变化，场发射开启场从 10 μA/cm2 的 3.58 V/μm 降低到 2.5 V/μm，场增强因子从 1.1 × 104 增加到 5.9 × 104。由于低功函数、低开启场和高场增强因子，β-MoO3 纳米结构被发现比 α-MoO3 纳米结构好得多，并且有望成为有用的应用。