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In this study, we tried to understand the difference in the mechanical properties (elastic modulus, E & hardness, H) values of CIGS compound semiconductors measured using the Berkovich indenter and the sharper cube corner and conical indenter. Adopted continuous stiffness measurement technique to characterize it along with the indentation depth. The depth was up to 1000 nm, and E and H values w ere obtained according to the depth. The projected contact area of the cube edge and the conical indenter was calculated assuming the two indenters had an ideal shape. In the case of the Berkovich indenter, which is the subject of comparison, both calculated values assuming an ideal shape and experimental values were used. Cube-corner and conical tip showed lower load at the same depth of 1000 nm compared to Berkovich indenter. This means that the same depth of indentation was achieved even at a low load, which could affect the value of the mechanical properties of the thin film. The cube-corner tip and the conical tip have a sharp shape with a projected contact area about 6 times smaller than that of the Berkovich tip. It was observed that not only the effect of grain boundaries of the microstructure of the CIGS thin film, but also the effect of reflecting the characteristics of the Mo substrate had a significant effect on the mechanical properties of the CIGS thin film.

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Plasmonic nanostructured metals have many advantages for applications in high-performance surface-enhanced Raman scattering (SERS) spectroscopy. In particular, unique designing nanostructures with bicontinuous ligaments surrounded by cylindrical voids with tunable dense pores from a few to hundreds of nanometers can be utilized for the high-performance SERS-active substrate. Here, a fabrication strategy is reported to prepare hierarchically arranged micro/nanostructures of wrinkled nanoporous gold (WNPG) films, which involves laminating of the dealloyed Au film on the heat-shrinkable shape-memory polymer film and geometrical modulation of the substrate. As a result, the various types of WNPG films are crafted with a remarkable density of cracks in the structured surface area. Specifically, the WNPG films consisting of multilayered overlapping features are explored and used as the SERS-active substrate. This dual porosity coupled with localized surface plasmon resonance estimated by numerical simulation in a suitable model of bicontinuous ligaments is found to be the core mechanism for the enhancement of SERS sensitivity, which quantitatively characterizes the "hot spots" from the surface to interlayers. These suggested characteristic features are fully assessed by applying a series of dye molecules and DNA strands on the prepared SERS substrate, demonstrating the enhanced intensity of the Raman scattering signals on the optimized WNPG surface.

In this study, a Sb2S3–Cu2S composite was synthesized by adding Cu2S, which exhibits a negative Poisson’s ratio in a two-dimensional structure, to improve the mechanical properties of the Sb2S3 compound semiconductor. The sol–gel method was used for the preparation of Sb2S3 precursor solution and after mixing synthesized by heat treatment at 260–280 °C. Cu2S growing in a plate-like structure with the Cu2S powders prepared by performing a sulfurization of Cu using polysulfide, it was spin-coated on gold-coated FTO glass substrates. Finally, the Cu2S powders were chemically combined with Sb2S3 pillars to grow in the form of cudgels with acicular structures attached to the pillar structure. The acicular structure attached to the surface of the Sb2S3 pillar structure was observed to be calcostibite (CuSbS2). The mechanical energy absorption of the bare Sb2S3 pillar and Sb2S3–Cu2S cudgels structures was measured through nanoindentation experiments of flat-top tip with a diameter of 2 μm. It was observed that the external energy absorption (energy dissipation) ability of the Sb2S3–Cu2S cudgels structure was improved by more than five times which was compared to the bare Sb2S3 pillar structure.