In order to prevent microroughness generation on the Si wafer surface in buffered hydrogen fluoride (BHF), the addition of a surfactant to BHF was investigated. It was found that mieroroughness generation on the Si wafer surface in BHF was prevented by adding the several 10 ppm surfactant. Also, the dissolution of Si into BHF from the Si wafer surface was suppressed by adding the surfactant. Microroughness generation was suppressed by lowering the N[-I4F concentration in BHF and the dissolution oi Si depended on the OH concentration rather than on the HF concentration in BHE For a wide range of HF and NH4F concentrations in BHF, the hydrocarbon anionic surfactant is effective for the prevention of microroughness generation. The prevention of microroughness generation is explained by the adsorption of the surfactant molecules on the Si wafer surface in accordance with the Langmuir type adsorption equation.

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Due to its high sensitivity to changes in the environmental dielectric constant, localized surface plasmon resonance (LSPR) is utilized for various sensing materials. However, because of this high sensitivity, it is difficult to detect a specific substance among mixed materials. Here, we enhanced the size selectivity using a metal nanostructure. By preparing a cup-like metal nanostructure that is the same size as a virus, this cup-like structure may be able to capture a virus, and thus the LSPR characteristics would change. This phenomenon would not occur for larger materials, such as animal cells, i.e., this cup-like structure may have selectivity for material size. In this paper, we fabricated metal nanocups out of two-dimensional colloidal crystals by exploiting the difference of interfacial energy at a dielectric/metal interface. The size selectivity and plasmon characteristics of the fabricated metal nanocups were investigated with model viruses, i.e., virus-like polystyrene (PSt) nanoparticles with almost the same dielectric constant and size as a virus. As a result, the transmission spectra show a 20-nm red shift in the visible light range before and after adsorption of the model virus. Field emission scanning electron microscopy (FE-SEM), optical microscopy, UV–vis spectrometry and contact angle measurement results are also discussed.

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Titanium oxide (anatase) particles were prepared using selective Ba leaching from BaTiO3. The anatase powder was flaky. Its photocatalytic activity for the decomposition of gaseous 2-propanol (IPA) was improved by grafting tungsten-based Keggin-type heteropolyacids (PW12: ([PW12O40] 3-). PW12-grafted anatase powder immobilized onto Pyrex glass plates with amorphous TiO2 exhibited better retention of the UV induced hydrophilicity than the pure anatase. Results suggest that the electron scavenger property of PW12 plays an important role in the overall photocatalytic performance of the material.