Growth of Large-Scale, Large-Size, Few-Layered α-MoO3 on SiO2 and Its Photoresponse Mechanism

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• 作者：Yu Wang ; Xiang Du ; Jiming Wang ; Mingze Su ; Xi Wan ; Hui Meng ; Weiguang XieJianbin Xu ; Pengyi Liu
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2017
• 出版时间：February 15, 2017
• 年：2017
• 卷：9
• 期：6
• 页码：5543-5549
• 全文大小：501K
• ISSN：1944-8252

文摘

Layered α-MoO₃ is a multifunctional material that has significant application in optoelectronic devices. In this study, we show the growth of large-scale, large-size, few-layered (FL) α-MoO₃ nanosheet directly on technical substrates (SiO₂ and Si) by physical vapor deposition. We suggest that the growth is self-limiting in the [010] direction because of the re-evaporation and high diffusion capacity of MoO_x species at high temperature. As-prepared FL α-MoO₃ is nonconductive and shows poor response to photoillumination with wavelength of 405 and 630 nm. Its work function is strongly altered by the substrate. Improvement of conductivity and photoresponse is observed after the FL device is annealed in vacuum. Line defects along the [001], [100], and [101] directions belonging to the generation of O_s and O_a vacancy states appear, and the interfacial effect is suppressed. Scanning near-field optical microscope shows that the defects are absorption sites. Kelvin probe force microscope reveals decrease of apparent work function under illumination, which confirms that electrons are excited from defects states. Our findings show that intense studies on defect engineering are required to push forward the application of two-dimensional metal oxides.