▎ 摘　　要

Graphene has a high intrinsic thermal conductivity and a high electron mobility. The thermal conductivity of graphene can be significantly reduced when different carbon isotopes are mixed, which can enhance the performance of thermoelectric devices. Here we synthesize isotopic C-12/C-13 random mixes and isotope superlattices (SLs) with periods ranging from 46 to 225 nm by chemical vapor deposition. Raman optothermal conductivity measurements of these SL structures show an approximately 50% reduction in thermal conductivity compared to pristine C-12 graphene. This average reduction is similar to the random isotope mix. The reduction of the thermal conductivity in the SL is well described by a model of pristine graphene and an additional quasione-dimensional periodic interfacial thermal resistance of (2.5 +/- 0.5) x 10(-11) m(2) K W-1 for the C-12/C-13 boundary. This is consistent with a large anisotropic thermal conductivity in the SL, where the thermal conductivity depends on the orientation of the C-12/C-13 boundary.