Morphological and Spectroscopic Characterizations of Monolayer and Few-Layer MoS2 and WSe2 Nanosheets under Oxygen Plasma Treatment with Different Excitation Power: Implications for Modulating Electronic Properties,ACS Applied Nano Materials

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Morphological and Spectroscopic Characterizations of Monolayer and Few-Layer MoS2 and WSe2 Nanosheets under Oxygen Plasma Treatment with Different Excitation Power: Implications for Modulating Electronic Properties
ACS Applied Nano Materials ( IF 5.3 ) Pub Date : 2020-04-09 , DOI: 10.1021/acsanm.0c00406
Chengjie Pei ₁ , Xiya Li ₁ , Huacheng Fan ₁ , Jia Wang ₁ , Hui You ₁ , Peng Yang ₁ , Cong Wei ₁ , Shuang Wang ₁ , Xiaogang Shen ₁ , Hai Li ₁

Affiliation

Modulating the electronic properties of transition metal dichalcogenides (TMDCs) by oxygen plasma treatment has attracted great attention. However, the effect of excitation power on oxidation and etching process in oxygen plasma treatment still lacks systematic investigation. In this work, optical microscopy, Raman and photoluminescence spectroscopy, atomic force microscopy, and X-ray photoelectron spectroscopy (XPS) are used to characterize the oxidation and etching behaviors of atomically thin MoS₂ and WSe₂ nanosheets treated by oxygen plasma with different excitation powers. The oxidation process is in a predominant position from 0 to 20 s, while etching is the dominant behavior from 30 to 120 s for monolayer (1L) to trilayer (3L) MoS₂ and WSe₂ nanosheets under low power plasma. However, etching is the apparent behavior of the MoS₂ surface all through the middle and high power oxygen plasma. Similar etching was also found for WSe₂ except for the first 10 s treatment under middle and high power. Interestingly, the top layer of bilayer (2L) and 3L WSe₂ nanosheets can be oxidized to the WO₃ layer homogeneously with height increased by ∼2 nm after 10 s treatment under optimal excitation power. In addition, thinning of the top layer MoS₂ and WSe₂ took the same time, while more time was taken for WSe₂ to thin the following layer. Our results indicate that 1L and 2L MoS₂ showed better stability than 1L and 2L WSe₂, while the reverse situation was observed for 3L WSe₂ under low power plasma. WSe₂ was more stable than MoS₂ under middle and high power plasma, which could originate from the different protection abilities between WO₃ and MoO₃. Our study might provide useful information for thinning and controlled formation of a surface oxide layer on TMDCs nanosheets, which is of great interest in modulating their electronic properties.

中文翻译：

氧等离子体处理不同激发功率下单层和少层MoS ₂和WSe ₂纳米片的形态学和光谱学表征：对电子性质的调控

通过氧等离子体处理来调节过渡金属二卤化物（TMDC）的电子性能引起了极大的关注。然而，激发功率对氧等离子体处理中的氧化和蚀刻工艺的影响仍然缺乏系统的研究。在这项工作中，使用光学显微镜，拉曼光谱和光致发光光谱，原子力显微镜和X射线光电子能谱（XPS）表征了通过氧等离子体在不同激发条件下处理的原子薄MoS ₂和WSe ₂纳米片的氧化和蚀刻行为。权力。对于单层（1L）到三层（3L）MoS ₂和WSe ，氧化过程的主要位置是0到20 s，而蚀刻是30到120 s的主要行为。在低功率等离子体下_2个纳米片。但是，蚀刻是整个中高功率氧等离子体中MoS ₂表面的明显行为。除了在中功率和高功率下进行的前10 s处理之外，还发现了对WSe _2的类似蚀刻。有趣的是，在最佳激发功率下处理10 s后，双层（2L）和3L WSe ₂纳米片的顶层可以被均匀氧化为WO ₃层，高度增加了约2 nm。此外，减薄顶层的MoS的₂和WSE ₂采取了同样的时间，而更多的时间采取WSE ₂至薄下面层。我们的结果表明1L和2L MoS ₂与1L和2L WSe _2相比，它显示出更好的稳定性，而在低功率等离子体下观察到3L WSe ₂的相反情况。WSe ₂在中高功率等离子体下比MoS ₂稳定，这可能是由于WO ₃和MoO ₃之间的保护能力不同所致。我们的研究可能会为在TMDCs纳米片上减薄和控制表面氧化物层的形成提供有用的信息，这对调节其电子性能非常感兴趣。

更新日期：2020-04-09

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