Graphene grain size-dependent synthesis of single-crystalline Sb2Te3 nanoplates and the interfacial thermal transport analysis by Raman thermometry

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The electrical and thermal transport at the interface of hetero-structures plays a critical role in device performance. Here, we successfully grew single-crystalline Sb 2 Te 3 nanoplates (NPs) on graphene by the solvothermal method due to the small lattice mismatch (∼4%) between c-axis aligned rhombohedral Sb 2 Te 3 and bridge sites of graphene. The growth of Sb 2 Te 3 NPs was bound by the graphene grain boundary, and the average size of Sb 2 Te 3 NPs increased from 2.2 to 8.8 μm, with a maximum of 21 μm, as the graphene grain size increased from 2.2 to 9.4 μm. The Ohmic contact was realized between the Sb 2 Te 3 NP and graphene. However, a limited thermal boundary conductance ( K BD , average and maximum:13.45 and 17.69 MW m −2 K − 1 ) was observed by Raman thermometry due to the large acoustic mismatch (Debye temperature difference = 1935 K). Both small lattice and acoustic mismatch was required to achieve high K BD . The electrical and thermal contact was poor (average and minimum K BD : 0.16 and 0.08 MW m −2 K − 1 ) when Sb 2 Te 3 NPs were separately synthesized and drop-deposited on graphene. This demonstrated that the direct growth of Sb 2 Te 3 on graphene was very important, rather than the simple transfer method, to achieve good electrical and thermal contact at the interface of hetero-structures.