Probing the Intrinsic Strain in Suspended Graphene Films Using Electron and Optical Microscopy

Quantifying the intrinsic properties of 2D materials is of paramount importance for advancing their applications. Large-scale production of 2D materials merits the need for approaches that provide direct information about the role of growth substrate on 2D material properties. Transferring the 2D material from its growth substrates can modify the intrinsic properties of the asgrown 2D material. In this study, suspended chemical vapor deposition (CVD) graphene films are prepared directly on their growth substrates in a high-density grid array. The approach facilitates the quantification of intrinsic strain and doping in suspended CVD graphene films. To achieve this, transmission electron microscopy and large-area Raman mapping are employed. Remarkably, the analysis reveals consistent patterns of compressive strain (approximate to-0.2%) both in the diffraction patterns and Raman maps obtained from these suspended graphene films. By conducting investigations directly on the growth substrates, the potential influences introduced during the transfer process are circumvented effectively. Consequently, the methodology offers a robust and reliable means of studying the intrinsic properties of 2D materials in their authentic form, uninfluenced by the transfer-induced alterations that may skew the interpretation of their properties. Characterizing single layer graphene (SLG) films directly on their growth substrates is highly beneficial to study their intrinsic properties. Charge doping and strain are among the prominent properties of interest to assess SLG quality. In this work, the use of selected area electron diffraction and Raman spectroscopy as means to quantify intrinsic strain in chemical vapor deposition grown SLG films is demonstrated.image

Automated summary

Quantifying the intrinsic properties of 2D materials is crucial for their applications. This study demonstrates a method for preparing suspended chemical vapor deposition (CVD) graphene films directly on their growth substrates, allowing for the quantification of intrinsic strain and doping. The results show consistent patterns of compressive strain in the films and highlight the importance of studying materials directly on their growth substrates to avoid transfer-induced alterations.