Micro-Raman spectroscopy investigation of deformation transfer at the interface between Bi2Se3 nanoflakes and a flexible substrate

Abstract

The experimental investigation of the mechanical behavior at the interface between a few-layer Bi₂Se₃ nanoflake and flexible substrate is of great significance for the structural design and performance development of electronic devices based on topological insulator nanostructure. A quantitative micro-Raman study of the interfacial deformation transfer behavior was performed in this work. Combined with micro-Raman spectroscopy and in-situ loading, the Raman shift-strain coefficients of A_1g phonon modes for Bi₂Se₃ nanoflakes with different longitudinal and transverse dimensions on the flexible substrate were calibrated, and the longitudinal dimensions were determined using a rapid and reliable optical identification method developed based on the optical contrast difference. In addition, an interfacial bonding phenomenological model was proposed to analyze the process of interfacial re-bonding after debonding with increasing strain and the interfacial bonding enhancement after cyclic loading. The influences of transverse dimension and thickness of Bi₂Se₃ nanoflakes on the interfacial bonding and deformation transfer were quantified by calibrating Raman shift-strain coefficients for multiple samples and were further attributed to the edge effect of the interfacial shear force and decline of interfacial deformation transfer with the layers, respectively.