Oxidation Kinetics of WTe2 Surfaces in Different Environments,ACS Applied Electronic Materials

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Oxidation Kinetics of WTe2 Surfaces in Different Environments
ACS Applied Electronic Materials ( IF 4.3 ) Pub Date : 2020-06-28 , DOI: 10.1021/acsaelm.0c00380
Fei Hou _{1,

2} , Dawei Zhang ₁ , Pankaj Sharma _{1,

2} , Simrjit Singh ₁ , Tom Wu ₁ , Jan Seidel _{1,

2}

Affiliation

Tungsten ditelluride, WTe₂, a layered transition metal dichalcogenide (TMD), displays superior physical and electronic properties and offers a fertile playground to study physics in low-dimensional materials with nontrivial band structures. However, WTe₂ oxidizes in the air, leading to the formation of a surface oxide layer that introduces disorder and deteriorates electronic charge transport. This surface oxide, therefore, suppresses the intrinsic properties of WTe₂ and can lead to the degradation of device performance. In this study, we report the formation of surface oxide and its kinetics in WTe₂ single crystals through a combination of atomic force microscopy (AFM), Raman spectroscopy, and ellipsometry measurements. The measurements reveal nonuniform surface oxide dynamics, which upon saturation after several hours of atmospheric exposure yields a self-limiting approximately 2.5-nm-thick amorphous surface layer. In addition, in a controlled environment involving a continuous flow of nitrogen (N₂), the formation of surface oxide is considerably impeded. These results offer insight into the surface degradation mechanisms of WTe₂, which should be taken into account when striving for the optimal design and performance of WTe₂-based devices.

中文翻译：

不同环境下WTe ₂表面的氧化动力学

碲化钨钨（WTe ₂）是一种层状过渡金属二硫化钨（TMD），具有优异的物理和电子性能，并为研究具有非平凡带结构的低维材料的物理学提供了肥沃的场所。然而，WTe ₂在空气中氧化，导致形成表面氧化层，该表面氧化层引入无序并破坏了电子电荷的传输。因此，该表面氧化物抑制了WTe ₂的固有特性，并可能导致器件性能下降。在这项研究中，我们报告了WTe ₂中表面氧化物的形成及其动力学通过原子力显微镜（AFM），拉曼光谱和椭偏仪测量相结合来形成单晶。这些测量揭示了不均匀的表面氧化物动力学，该动力学在大气暴露几小时后饱和后会产生自限制的约2.5 nm厚的非晶表面层。另外，在涉及氮（N ₂）连续流动的受控环境中，显着阻碍了表面氧化物的形成。这些结果提供了对WTe ₂的表面降解机制的洞察力，在争取基于WTe ₂的设备的最佳设计和性能时应考虑到这一点。

更新日期：2020-07-28

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