Fabrication of nanoindentation array-based SERS substrate using Conical and Berkovich indenters

Abstract

This paper reports a study of the effect of indenter geometry on the morphologies of the indentation arrays using a home-made nanoindentation system. Two typical indenters, that is, Conical and Berkovich indenters are chosen to conduct all the indentation process on a pure aluminum block surface. Single-row and multiple-row indentation arrays are machined, and the effect of the spacing value between the adjacent indentations with different indenters are studied in detail. Results show that the overlapping of the indentations and the material filling by the following penetration are the two main factors of the surface topography quality of the obtained structures. The smaller the spacing value is, the larger the indentation deformation is, and the worse the quality of the periodic structure is. In addition, the surface enhanced Raman scattering (SERS) substrates are prepared by the machined indentation arrays, and the SERS spectra is measured using Rhodamine 6G (R6G). The results show that a higher Raman enhancement factor is obtained on the Conical indentation arrays, which is attributed to the higher depth-to-width ratio of the indentation array. Therefore, this work can provide a guidance for the preparation of SERS substrate with suitable indenter geometries and the indentation interval values.