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

Abstract

© 2019 Elsevier LtdThe electrical and thermal transport at the interface of hetero-structures plays a critical role in device performance. Here, we successfully grew single-crystalline Sb2Te3 nanoplates (NPs) on graphene by the solvothermal method due to the small lattice mismatch (∼4%) between c-axis aligned rhombohedral Sb2Te3 and bridge sites of graphene. The growth of Sb2Te3 NPs was bound by the graphene grain boundary, and the average size of Sb2Te3NPs 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 Sb2Te3 NP and graphene. However, a limited thermal boundary conductance (KBD, 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 KBD. The electrical and thermal contact was poor (average and minimum KBD: 0.16 and 0.08 MW m−2 K−1) when Sb2Te3 NPs were separately synthesized and drop-deposited on graphene. This demonstrated that the direct growth of Sb2Te3 on graphene was very important, rather than the simple transfer method, to achieve good electrical and thermal contact at the interface of hetero-structures