Epitaxial Growth of Two-dimensional Insulator Monolayer Honeycomb BeO

dc.creatorZhang, Hui
dc.creatorHolbrook, Madison
dc.creatorCheng, Fei
dc.creatorNam, Hyoungdo
dc.creatorLiu, Mengke
dc.creatorPan, Chi-Ruei
dc.creatorWest, Damien
dc.creatorZhang, Shengbai
dc.creatorChou, Mei-Yin
dc.creatorShih, Chih-Kang
dc.description.abstractThe emergence of two-dimensional (2D) materials launched a fascinating frontier of flatland electronics. Most crystalline atomic layer materials are based on layered van der Waals materials with weak interlayer bonding, which naturally leads to thermodynamically stable monolayers. We report the synthesis of a 2D insulator composed of a single atomic sheet of honeycomb structure BeO (h-BeO), although its bulk counterpart has a wurtzite structure. The h-BeO is grown by molecular beam epitaxy (MBE) on Ag(111) thin films that are also epitaxially grown on Si(111) wafers. Using scanning tunneling microscopy and spectroscopy (STM/S), the honeycomb BeO lattice constant is determined to be 2.65 Å with an insulating band gap of 6 eV. Our low-energy electron diffraction measurements indicate that the h-BeO forms a continuous layer with good crystallinity at the millimeter scale. Moiré pattern analysis shows the BeO honeycomb structure maintains long-range phase coherence in atomic registry even across Ag steps. We find that the interaction between the h-BeO layer and the Ag(111) substrate is weak by using STS and complementary density functional theory calculations. We not only demonstrate the feasibility of growing h-BeO monolayers by MBE, but also illustrate that the large-scale growth, weak substrate interactions, and long-range crystallinity make h-BeO an attractive candidate for future technological applications. More significantly, the ability to create a stable single-crystalline atomic sheet without a bulk layered counterpart is an intriguing approach to tailoring 2D electronic materials.
dc.description.departmentCenter for Dynamics and Control of Materials
dc.description.sponsorshipThis research was partially supported by the National Science Foundation through the Center for Dynamics and Control of Materials: an NSF MRSEC under Cooperative Agreement No. DMR- 22 1720595. This research was also supported with grants from the Welch Foundation (F-1672), the US National Science Foundation (DMR-1808751, EFMA-1542747, EFMA-1542798), the US Airforce (FA2386-18-1-4097), and Academia Sinica (AS-TP-106-M07).
dc.relation.ispartofCenter for Dynamics and Control of Materials Publications
dc.subject2D electronic material
dc.subjectscanning tunneling microscopy
dc.subjecthoneycomb BeO structure
dc.subjectepitaxial growth
dc.subjectberyllium oxide
dc.subjectmolecular beam epitaxy
dc.titleEpitaxial Growth of Two-dimensional Insulator Monolayer Honeycomb BeO

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