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Are 2D Interfaces Really Flat?



Zhihui Cheng, Huairuo Zhang, Son Le, Hattan Abuzaid, Guoqing Li, Yifei Yu, Albert Davydov, Linyou Cao, Aaron Franklin, Curt A. Richter


Two-dimensional (2D) materials are amenable to external mechanical deformation and thus forming bubbles and wrinkles. However, little is known about the dynamics of 2D interfaces, especially their flatness under different conditions. Here we use cross-sectional transmission electron microscopy (TEM) to investigate various 2D interfaces (2D-2D and 3D-2D) and observe that the dry transfer of hexagonal boron nitride (hBN) can dramatically alter the interface structure. We characterize and compare the flatness of these 2D interfaces down to sub-nanometer accuracy. The Ni-MoS2 interfaces are more uneven and have larger nanogaps compared to other metal-2D interfaces. We then correlate the electrical properties of an example field effect transistor to the interfacial transformation. The improved device performance is likely due to the interface interaction at both the channel and contacts. Overall, our observations reveal the intricacy of 2D interfaces and their significant dependence on the processes used in their fabrication. Our work paves the way for a deeper understanding of these critical interfaces and their role in device performance.
ACS Nano


two-dimensional, nanoelectronics, electrical contacts, transmission electron microscopy (TEM)


Cheng, Z. , Zhang, H. , Le, S. , Abuzaid, H. , Li, G. , Yu, Y. , Davydov, A. , Cao, L. , Franklin, A. and Richter, C. (2022), Are 2D Interfaces Really Flat?, ACS Nano, [online],, (Accessed July 23, 2024)


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Created March 15, 2022, Updated November 29, 2022