Surface morphology-modulated electrical conductivity behavior in 2D anisotropic exfoliated nanoribbons

Although mechanical exfoliation allows the preparation of flakes of two-dimensional (2D) layered materials from their bulk counterparts in a cost-efficient and versatile manner, it has been difficult to correlate the surface morphology of the exfoliated flakes with their fundamental electrical characteristics. In this study, we used mechanical exfoliation to prepare 2D layered titanium trisulfide (TiS₃) nanoribbons having thicknesses varying from a few to tens of nanometers. Interestingly, the bulk electrical conductivity of the exfoliated TiS₃ nanoribbons was correlated to their surface roughness, rather than their thickness. Furthermore, at temperatures from 80 K to 280 K, the distinctive behavior of the electrical conductivity in the exfoliated nanoribbons was also significantly dependent on the surface roughness. Measurements of intrinsic field-effect electron mobilities unveiled that the dominant mobility scattering mechanism transitioned from phonon scattering to coulombic and/or surface roughness scattering upon increasing the surface roughness, thereby resulting in distinctive temperature-dependent electrical conductivity behavior. Accordingly, simple measurements of surface morphologies can provide information regarding the fundamental electrical properties of 2D exfoliated layered flakes, potentially leading to greater use of layered materials in semiconductor applications. (paper)