| AVS 66th International Symposium & Exhibition | |
| 2D Materials | Wednesday Sessions |
| Session 2D+EM+MI+MN+NS+QS-WeM |
| Session: | Novel 2D Materials |
| Presenter: | Zhuozhi Ge, University of Wisconsin |
| Authors: | Z. Ge, University of Wisconsin H. Zhang, West Virginia University L. Liu, West Virginia University C. Yan, West Virginia University M. Weinert, University of Wisconsin L.L. Li, West Virginia University |
| Correspondent: | Click to Email |
At the single layer limit, transition metal dichalcogenides (TMDs) can adopt two different structural variants depending on the anionic environment around the metal ions: the anions are arranged in trigonal prismatic fashion in the 1H polymorph, whereas in 1T the arrangement is octahedral. While bulk 1T NbSe2 doesn’t exist in nature, here we show that single layer 1T NbSe2 polymorph can be grown by molecular beam epitaxy on epitaxial graphene/SiC(0001) substrates. A (Ö13xÖ13) Star-of-David charge density waves is observed by in situ scanning tunnelling microscopy, which persists above room temperature. A gap of 0.50 eV is further observed by tunnelling spectroscopy and angle resolved photoemission spectroscopy, indicating that this monolayer 1T phase of NbSe2 is also a Mott insulator, similar to that of bulk 1T TaS2. Our findings indicate that the presence of epitaxial constraints can generate structural configurations that are prohibited in fully-bonded TMD crystals. These findings and their implication on the collective electronic states of single layer 1T-NbSe2 will be discussed at the meeting.