Structural, optical, and magnetic properties of Ag, Mn and Ar ions implanted ZnO thin films: effect of implantation dose and stopping energy.

Herein, we systematically studied the effect of various excitation processes on the structural, optical, and magnetic properties of ZnO films implanted with 80 keV Ar, 110 keV Mn, and 190 keV Ag ions. Four different doses of 1 × 10, 1 × 10, 1 × 10, and 2 × 10 ions per cm were used for implantation. It was observed that the structural, optical, and magnetic properties of the implanted samples were dominantly affected at the highest dose of 2 × 10 ions per cm.

Random nanohole arrays and its application to crystalline Si thin foils produced by proton induced exfoliation for solar cells.

We report high efficiency cell processing technologies for the ultra-thin Si solar cells based on crystalline Si thin foils (below a 50 µm thickness) produced by the proton implant exfoliation (PIE) technique. Shallow textures of submicrometer scale is essential for effective light trapping in crystalline Si thin foil based solar cells. In this study, we report the fabrication process of random Si nanohole arrays of ellipsoids by a facile way using low melting point metal nanoparticles of indium which were vacuum-deposited and dewetted spontaneously at room temperature.

Enhanced efficiency of crystalline Si solar cells based on kerfless-thin wafers with nanohole arrays.

Several techniques have been proposed for kerfless wafering of thin Si wafers, which is one of the most essential techniques for reducing Si material loss in conventional wafering methods to lower cell cost. Proton induced exfoliation is one of promising kerfless techniques due to the simplicity of the process of implantation and cleaving. However, for application to high efficiency solar cells, it is necessary to cope with some problems such as implantation damage removal and texturing of (111) oriented wafers.

Silicon nanodisk array design for effective light trapping in ultrathin c-Si.

The use of ultrathin c-Si (crystalline silicon) wafers thinner than 20 μm for solar cells is a very promising approach to realize dramatic reduction in cell cost. However, the ultrathin c-Si requires highly effective light trapping to compensate optical absorption reduction. Conventional texturing in micron scale is hardly applicable to the ultrathin c-Si wafers; thus, nano scale texturing is demanded.

Role of subnano-, nano- and submicron-surface features on osteoblast differentiation of bone marrow mesenchymal stem cells.

Subnano, nano and sub-micron surface features can selectively activate integrin receptors and induce osteoblast differentiation of bone marrow mesenchymal stem cells. Although it is widely accepted that nanoscale titanium surface roughness may promote differentiation of various osteoblast lineages, there has been no clear report on the threshold dimension of surface features and the optimized dimensions of surface features for triggering integrin activation and stem cell differentiation. This study systematically controlled titanium surface features from the sub-nano to sub-micron scales and investigated the corresponding effects on stem cell responses, such as integrin activation, cyclins, key transcriptional genes of osteoblast differentiation and osteoblastic phenotype genes.

Hardness and nitrogen bonding structure of AlxTi1-xN/CrN multilayer hard coating.

AlxTi1-xN/CrN multilayer coatings were fabricated by magnetron sputtering and those hardness variations were studied by observing the crack propagation and measuring the chemical bonding state of nitrides by Ti addition. While AlN/CrN multilayer shown stair-like crack propagation, AlxTi1-xN/CrN multilayer illustrated straight crack propagation. Most interestingly, Ti addition induced more broken nitrogen bonds in the nitride multilayers, leading to the reduction of hardness.

The effects of nitrogen bonding on hardness of AIN/CrN multilayer hard coatings.

AIN/CrN multilayer hard coatings with various bilayer thicknesses were fabricated by a reactive sputtering process. The microstructural and mechanical characterizations of multilayer coatings were investigated through transmission electron microscope (TEM) observations and the hardness measurements by nano indentation. In particular, the variation of chemical bonding states of the bilayer nitrides was elucidated by near edge X-ray absorption fine structure (NEXAFS) spectroscopy.

Analysis on migration and activation of live macrophages on transparent flat and nanostructured titanium.

The immunotoxicity of implanted nanostructured titanium is a paramount issue for vascular, dental and orthopedic applications. However, it has been unclear whether implanted surface nanostructures can inhibit or aggrevate inflammatory responses. Herein, macrophage activation, as evidence of migration, on transparent flat and nanostructured titanium correlated with pro-inflammatory protein synthesis and cytokine release.