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Epitaxial co-deposition growth of CaGe2 films by molecular beam epitaxy for large area germanane

  • Igor V. Pinchuk (a1), Patrick M. Odenthal (a2), Adam S. Ahmed (a3), Walid Amamou (a4), Joshua E. Goldberger (a5) and Roland K. Kawakami (a6)...

Two-dimensional crystals are an important class of materials for novel physics, chemistry, and engineering. Germanane (GeH), the germanium-based analogue of graphane (CH), is of particular interest due to its direct band gap and spin–orbit coupling. Here, we report the successful co-deposition growth of CaGe2 films on Ge(111) substrates by molecular beam epitaxy and their subsequent conversion to germanane by immersion in hydrochloric acid. We find that the growth of CaGe2 occurs within an adsorption-limited growth regime, which ensures stoichiometry of the film. We utilize in situ reflection high energy electron diffraction (RHEED) to explore the growth temperature window and find the best RHEED patterns at 750 °C. Finally, the CaGe2 films are immersed in hydrochloric acid to convert the films to germanane. Auger electron spectroscopy of the resulting film indicates the removal of Ca, and RHEED patterns indicate a single-crystal film with an in-plane orientation dictated by the underlying Ge(111) substrate. X-ray diffraction and Raman spectroscopy indicate that the resulting films are indeed germanane. Ex situ atomic force microscopy shows that the grain size of the germanane is on the order of a few micrometers, being primarily limited by terraces induced by the miscut of the Ge substrate. Thus, optimization of the substrate could lead to the long-term goal of large area germanane films.

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Y. Zhang , Y-W. Tan , H.L. Stormer , and P. Kim : Experimental observation of the quantum Hall effect and Berry's phase in graphene. Nature 438, 201204 (2005).

A.K. Geim and K.S. Novoselov : The rise of graphene. Nat. Mater. 6, 183191 (2007).

E. Bianco , S. Butler , S. Jiang , O. Restrepo , W. Windl , and J.E. Goldberger : Stability and exfoliation of germanane: A germanium graphane analogue. ACS Nano 7, 44144421 (2013).

M. Konig , S. Wiedmann , C. Brune , A. Roth , H. Buhmann , L.W. Molenkamp , X-L. Qi , and S-C. Zhang : Quantum spin hall insulator state in HgTe quantum Wells. Science 318, 766770 (2007).

G. Vogg , C. Miesner , M.S. Brandt , M. Stutzmann , and G. Abstreiter : Epitaxial alloy films of Zintl-phase Ca(Si1-xGex)2. J. Cryst. Growth 223, 573576 (2001).

J.F. Morar and M. Wittmer : Metallic CaSi2 epitaxial films on Si(111). Phys. Rev. B 37, 26182621 (1988).

G. Vogg , M.S. Brandt , and M. Stutzmann : Polygermyne—A prototype system for layered germanium polymers. Adv. Mater. 12, 12781281 (2000).

J.J. Harris , B.A. Joyce , and P.J. Dobson : Oscillations in the surface structure of Sn-doped GaAs during growth by MBE. Surf. Sci. Lett. 103, L90L96 (1981).

J.H. Neave , B.A. Joyce , P.J. Dobson , and N. Norton : Dynamics of film growth of GaAs by MBE from RHEED observations. Appl. Phys. A 31, 18 (1983).

G. Zhang , H. Qin , J. Teng , J. Guo , Q. Guo , X. Dai , Z. Fang , and K. Wu : Quintuple-layer epitaxy of thin films of topological insulator Bi2Se3. Appl. Phys. Lett. 95, 053114 (2009).

A. Palenzona , P. Manfrinetti , and M.L. Fornasini : The phase diagram of the Ca-Ge system. J. Alloys Compd. 345, 144147 (2002).

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Journal of Materials Research
  • ISSN: 0884-2914
  • EISSN: 2044-5326
  • URL: /core/journals/journal-of-materials-research
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