Are 2D Interfaces Really Flat?
Are 2D Interfaces Really Flat?
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2D界面真的是平的吗？
DOI：
10.1021/acsnano.1c11493
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发表时间：
2022-03
期刊：
影响因子：
17.1
通讯作者：
Zhihui Cheng;Huairuo Zhang;S. Le;Hattan Abuzaid;Guoqing Li;Linyou Cao;A. Davydov;A. Franklin
中科院分区：
文献类型：
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作者：
Zhihui Cheng;Huairuo Zhang;S. Le;Hattan Abuzaid;Guoqing Li;Linyou Cao;A. Davydov;A. Franklin
二维（2D）货车德瓦尔斯材料在剥离和转移期间经受机械变形并因此形成气泡和褶皱。缺乏界面“平整度”会影响界面性质，例如由金属接触或绝缘层形成的界面性质。因此，了解二维界面的详细性质，特别是在不同条件下的平面度，是非常重要的。在这里，我们使用横截面扫描透射电子显微镜（STEM）研究各种二维界面（2D-2D和3D-2D）的堆叠，原子层沉积（ALD）和金属化的影响下。我们表征和比较hBN-2D和金属-2D界面的平坦度，直到埃分辨率。据观察，六方氮化硼（hBN）的干转移可以显着改变界面结构。当表征3D金属-2D界面时，我们发现Ni-MoS 2界面比其他金属-2D界面更不均匀，并且具有更大的纳米腔。基于二硫化钼的场效应晶体管的电特性与接触区和沟道区中的界面转变相关。在hBN封装后，器件的介电性能提高了40%，这可能是由于通道和接触处的界面相互作用。总的来说，这些观察结果揭示了二维界面的复杂性及其对制造工艺的依赖性。
Two-dimensional (2D) van der Waals materials are subject to mechanical deformation and thus forming bubbles and wrinkles during exfoliation and transfer. A lack of interfacial "flatness" has implications for interface properties, such as those formed by metal contacts or insulating layers. Therefore, an understanding of the detailed properties of 2D interfaces, especially their flatness under different conditions, is of high importance. Here we use cross-sectional scanning transmission electron microscopy (STEM) to investigate various 2D interfaces (2D-2D and 3D-2D) under the effects of stacking, atomic layer deposition (ALD), and metallization. We characterize and compare the flatness of the hBN-2D and metal-2D interfaces down to angstrom resolution. It is observed that the dry transfer of hexagonal boron nitride (hBN) can dramatically alter the interface structure. When characterizing 3D metal-2D interfaces, we find that Ni-MoS2 interfaces are more uneven and have larger nanocavities compared to other metal-2D interfaces. The electrical characteristics of a MoS2-based field-effect transistor are correlated to the interfacial transformation in the contact and channel regions. The device transconductance is improved by 40% after the hBN encapsulation, likely due to the interface interactions at both the channel and contacts. Overall, these observations reveal the intricacy of 2D interfaces and their dependence on the fabrication processes.