Vapor鈥揝olid Growth of High Optical Quality MoS2 Monolayers with Near-Unity Valley Polarization

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• 作者：Sanfeng Wu ; Chunming Huang ; Grant Aivazian ; Jason S. Ross ; David H. Cobden ; Xiaodong Xu
• 刊名：ACS Nano
• 出版年：2013
• 出版时间：March 26, 2013
• 年：2013
• 卷：7
• 期：3
• 页码：2768-2772
• 全文大小：389K
• 年卷期：v.7,no.3(March 26, 2013)
• ISSN：1936-086X

文摘

Monolayers of transition metal dichalcogenides (TMDCs) are atomically thin direct-gap semiconductors with potential applications in nanoelectronics, optoelectronics, and electrochemical sensing. Recent theoretical and experimental efforts suggest that they are ideal systems for exploiting the valley degrees of freedom of Bloch electrons. For example, Dirac valley polarization has been demonstrated in mechanically exfoliated monolayer MoS₂ samples by polarization-resolved photoluminescence, although polarization has rarely been seen at room temperature. Here we report a new method for synthesizing high optical quality monolayer MoS₂ single crystals up to 25 渭m in size on a variety of standard insulating substrates (SiO₂, sapphire, and glass) using a catalyst-free vapor鈥搒olid growth mechanism. The technique is simple and reliable, and the optical quality of the crystals is extremely high, as demonstrated by the fact that the valley polarization approaches unity at 30 K and persists at 35% even at room temperature, suggesting a virtual absence of defects. This will allow greatly improved optoelectronic TMDC monolayer devices to be fabricated and studied routinely.

Keywords:

molybdenum disulfide; monolayer; vapor鈭抯olid growth; photoluminescence; valley polarization; valleytronics