Large Area Atomically Flat Surfaces via Exfoliation of Bulk Bi2Se3 Single Crystals

CL Melamed, BR Ortiz, P Gorai, AD Martinez… - Chemistry of …, 2017 - ACS Publications
Chemistry of Materials, 2017ACS Publications
In this work, we present an exfoliation method that produces cm2-area atomically flat
surfaces from bulk layered single crystals, with broad applications such as for the formation
of lateral heterostructures and for use as substrates for van der Waals epitaxy. Single
crystals of Bi2Se3 were grown using the Bridgman method and examined with X-ray
reciprocal space maps, Auger spectroscopy, low-energy electron diffraction, and X-ray
photoelectron spectroscopy. An indium-bonding exfoliation technique was developed that …
In this work, we present an exfoliation method that produces cm2-area atomically flat surfaces from bulk layered single crystals, with broad applications such as for the formation of lateral heterostructures and for use as substrates for van der Waals epitaxy. Single crystals of Bi2Se3 were grown using the Bridgman method and examined with X-ray reciprocal space maps, Auger spectroscopy, low-energy electron diffraction, and X-ray photoelectron spectroscopy. An indium-bonding exfoliation technique was developed that produces multiple ∼100 μm thick atomically flat, macroscopic (>1 cm2) slabs from each Bi2Se3 source crystal. Two-dimensional X-ray diffraction and reciprocal space maps confirm the high crystalline quality of the exfoliated surfaces. Atomic force microscopy reveals that the exfoliated surfaces have an average root-mean-square (RMS) roughness of ∼0.04 nm across 400 μm2 scans and an average terrace width of 70 μm between step edges. First-principles calculations reveal exfoliation energies of Bi2Se3 and a number of other layered compounds, which demonstrate relevance of our method across the field of 2D materials. While many potential applications exist, excellent lattice matching with the III–V alloy space suggests immediate potential for the use of these exfoliated layered materials as epitaxial substrates for photovoltaic development.
ACS Publications
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