| AVS 61st International Symposium & Exhibition | |
| 2D Materials Focus Topic | Wednesday Sessions |
| Session 2D+EM+NS+SS+TF-WeM |
| Session: | Novel 2D Materials |
| Presenter: | Andrew Mannix, Northwestern University |
| Authors: | A.J. Mannix, Northwestern University B.T. Kiraly, Northwestern University B.L. Fisher, Argonne National Laboratory M.C. Hersam, Northwestern University N.P. Guisinger, Argonne National Laboratory |
| Correspondent: | Click to Email |
Bulk silicon has played a dominant role in the growth of microelectronics over the past 50 years. Considering the immense interest in two-dimensional (2D) materials (e.g., graphene, MoS2, phosphorene, etc.), the growth of Si in the 2D limit is of high relevance to the evolution of electronic materials. Utilizing atomic-scale, ultra-high vacuum (UHV) scanning tunneling microscopy (STM), we have investigated the 2D limits of Si growth on Ag(111). In agreement with previous reports of sp2-bonded silicene,1,2 we observe the evolution of ordered 2D phases, which we attribute to apparent Ag-Si surface alloys. At sufficiently high Si coverage, we observe the precipitation of crystalline, sp3-bonded Si(111) domains. These domains are capped with a √3 honeycomb phase that is indistinguishable from the √3 honeycomb-chained-trimer (HCT) reconstruction of Ag on Si(111).3,4,5 Additional evidence suggests that silicon intermixing with the Ag(111) substrate is followed by the precipitation of crystalline, sp3-bonded silicon nanosheets. These conclusions are supported by ex-situ atomic force microscopy (AFM), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). Even at the 2D limit, scanning tunneling spectroscopy shows that the sp3-bonded silicon nanosheets exhibit semiconducting electronic characteristics.
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