Van der Waals Epitaxial Growth of Two-Dimensional Single-Crystalline GaSe Domains on Graphene

Xufan Li, Leonardo Basile, Bing Huang, Cheng Ma, Jaekwang Lee, Ivan V. Vlassiouk, Alexander A. Puretzky, Ming Wei Lin, Mina Yoon, Miaofang Chi, Juan C. Idrobo, Christopher M. Rouleau, Bobby G. Sumpter, David B. Geohegan, Kai Xiao

Research output: Contribution to journalArticlepeer-review

107 Scopus citations

Abstract

Two-dimensional (2D) van der Waals (vdW) heterostructures are a family of artificially structured materials that promise tunable optoelectronic properties for devices with enhanced functionalities. Compared to transferring, direct epitaxy of vdW heterostructures is ideal for clean interlayer interfaces and scalable device fabrication. Here we report the synthesis and preferred orientations of 2D GaSe atomic layers on graphene (Gr) by vdW epitaxy. GaSe crystals are found to nucleate predominantly on random wrinkles or grain boundaries of graphene, share a preferred lattice orientation with underlying graphene, and grow into large (tens of micrometers) irregularly shaped, single-crystalline domains. The domains are found to propagate with triangular edges that merge into the large single crystals during growth. Electron diffraction reveals that approximately 50% of the GaSe domains are oriented with a 10.5 ± 0.3°interlayer rotation with respect to the underlying graphene. Theoretical investigations of interlayer energetics reveal that a 10.9°interlayer rotation is the most energetically preferred vdW heterostructure. In addition, strong charge transfer in these GaSe/Gr vdW heterostructures is predicted, which agrees with the observed enhancement in the Raman E21g band of monolayer GaSe and highly quenched photoluminescence compared to GaSe/SiO2. Despite the very large lattice mismatch of GaSe/Gr through vdW epitaxy, the predominant orientation control and convergent formation of large single-crystal flakes demonstrated here is promising for the scalable synthesis of large-area vdW heterostructures for the development of new optical and optoelectronic devices. (Figure Presented).

Original languageEnglish
Pages (from-to)8078-8088
Number of pages11
JournalACS Nano
Volume9
Issue number8
DOIs
StatePublished - Aug 25 2015

Bibliographical note

Publisher Copyright:
© 2015 American Chemical Society 2015.

Keywords

  • GaSe
  • chemical vapor deposition
  • graphene
  • heterostructures
  • van der Waals epitaxy

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