Nanomechanical characterisation of single-crystal Bi2Se3 topological insulator

Abstract

Topological insulators (TIs) are recently discovered high-tech materials where their potential use in nanoelectronic devices such as spintronics and quantum computers, due to their unique electronic features, can be a solution to the emerging need for high-bit data processing. Yet their mechanical properties are not well understood for their use in practical applications. With the objective of exploiting the nanomechanical behaviour of TIs, bulk single-crystal Bi2Se3 TI is grown by using the Bridgeman–Stockbarger method and mechanically characterised by the nanoindentation method. The Young's modulus and hardness were extracted from the load-displacement data by using Oliver and Pharr's standard method. Further, fracture toughness of the material was reported for the first time after comprehensive research of indentation crack length (ICL) methods. The grown Bi2Se3 exhibits hardness and Young's modulus as 323 MPa and 6.018 GPa at nanoscale, respectively. Fracture toughness of the TI was evaluated at 0.034 MPa m1/2 and elastic recovery was around 60% after the full unloading process.