Coherent heteroepitaxy of Bi 2 Se 3 on GaAs (111)B

We report the heteroepitaxy of single crystal thin films of Bi 2 Se 3 on the (111)B surface of GaAs by molecular beam epitaxy. We find that Bi 2 Se 3 grows highly c-axis oriented, with an atomically sharp interface with the GaAs substrate. By optimizing the growth of a very thin GaAs buffer layer before growing the Bi 2 Se 3 , we demonstrate the growth of thin films with atomically flat terraces over hundreds of nanometers. Initial time-resolved Kerr rotation measurements herald opportunities for probing coherent spin dynamics at the interface between a candidate topological insulator and a large class of GaAs-based heterostructures.