TY - GEN
T1 - High quality SnS van der Waals epitaxies on graphene buffer layer
AU - Wang, W.
AU - Leung, K. K.
AU - Fong, W. K.
AU - Wang, S. F.
AU - Hui, Y. Y.
AU - Lau, S. P.
AU - Surya, C.
N1 - Copyright:
Copyright 2013 Elsevier B.V., All rights reserved.
PY - 2012/12/1
Y1 - 2012/12/1
N2 - We report investigation of SnS van der Waals epitaxies (vdWEs) grown by molecular beam epitaxy (MBE) technique. Experimental results demonstrate an indirect bandgap of ∼1 eV and a direct bandgap of ∼1.25 eV. Substantial improvement in the crystallinity for the SnS thin films is accomplished by using graphene as the buffer layer. Using this novel growth technique we observed significant lowering in the rocking curve FWHM of the SnS films. Crystallite size in the range of 2-3 μm is observed which represents a significant improvement over the existing results. The absorption coefficient, α, is found to be of the order of 104 cm-1 which demonstrates sharp cutoff as a function of energy for films grown using graphene buffer layers indicating low concentration of localized states in the bandgap. Hole mobility as high as 81 cm2V-1s-1 is observed for SnS films on graphene/GaAs(100) substrates. The improvements in the physical properties of the films are attributed to the unique layered structure and chemically saturated bonds at the SnS/graphene interface. As a result, the interaction between the SnS thin films and the graphene buffer layer is dominated by a weak vdW force and structural defects at the interface, such as dangling bonds or dislocations, are substantially reduced.
AB - We report investigation of SnS van der Waals epitaxies (vdWEs) grown by molecular beam epitaxy (MBE) technique. Experimental results demonstrate an indirect bandgap of ∼1 eV and a direct bandgap of ∼1.25 eV. Substantial improvement in the crystallinity for the SnS thin films is accomplished by using graphene as the buffer layer. Using this novel growth technique we observed significant lowering in the rocking curve FWHM of the SnS films. Crystallite size in the range of 2-3 μm is observed which represents a significant improvement over the existing results. The absorption coefficient, α, is found to be of the order of 104 cm-1 which demonstrates sharp cutoff as a function of energy for films grown using graphene buffer layers indicating low concentration of localized states in the bandgap. Hole mobility as high as 81 cm2V-1s-1 is observed for SnS films on graphene/GaAs(100) substrates. The improvements in the physical properties of the films are attributed to the unique layered structure and chemically saturated bonds at the SnS/graphene interface. As a result, the interaction between the SnS thin films and the graphene buffer layer is dominated by a weak vdW force and structural defects at the interface, such as dangling bonds or dislocations, are substantially reduced.
KW - Graphene buffer layer
KW - Photovoltaic material
KW - SnS
KW - Van der Waals epitaxy
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U2 - 10.1117/12.930946
DO - 10.1117/12.930946
M3 - Conference contribution
AN - SCOPUS:84872846604
SN - 9780819491879
VL - 8470
T3 - Proceedings of SPIE - The International Society for Optical Engineering
BT - Thin Film Solar Technology IV
T2 - Thin Film Solar Technology IV
Y2 - 12 August 2013 through 13 August 2013
ER -