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Indium tin oxide (ITO) targets possess good performances, thereby used to produce high-quality ITO films in transparent electrodes of various optoelectronic devices. The performance of the target greatly affects the performances of prepared ITO films. However, effect of the overall performance of ITO targets on ITO films performance is still not fully understood. ITO films were prepared with four targets by magnetron sputtering in the similar condition in this study. Effects of crystal structure, resistivity, and oxygen content of the targets on photoelectric performances of ITO films were all evaluated. Results showed the important effect of target properties on obtained film characteristics. ITO films prepared by low resistivity targets are more evenly distributed on the substrate surface. Meanwhile, oxygen content of obtained ITO films decreased as oxygen content of ITO targets used in sputtering process increased. This also significantly improved the photoelectric performances. ITO thin films deposited using targets with low resistivity and low oxygen content exhibited excellent photoelectric performances. In this experiment, the prepared ITO film illustrated the lowest resistivity of 1.75×10−4 Ω·cm and average transmittance of 90.5%. In sum, these findings provided a certain experimental basis for further improving the performances of ITO films.

This paper introduces the recent progress in methodologies and their related applications based on the soft x-ray interference lithography beamline in the Shanghai synchrotron radiation facility. Dual-beam, multibeam interference lithography and Talbot lithography have been adopted as basic methods in the beamline. To improve the experimental performance, a precise real-time vibration evaluation system has been established; and the lithography stability has been greatly improved. In order to meet the demands for higher resolution and practical application, novel experimental methods have been developed, such as high-order diffraction interference exposure, high-aspect-ratio and large-area stitching exposure, and parallel direct writing achromatic Talbot lithography. As of now, a 25 nm half-pitch pattern has been obtained; and a cm2 exposure area has been achieved in practical samples. The above methods have been applied to extreme ultraviolet photoresist evaluation, photonic crystal and surface plasmonic effect research, and so on.

Metasurfaces with complex periodic nanoarrays have attracted a large amount of attention over the past decades due to their pronounced plasmonic and photonic properties. Though various metasurface properties have been theoretically and experimentally investigated, the realization of practical metasurface applications remains a big challenge due to very limited large-area complex nanostructure fabrication. In this paper, we demonstrate a parallel direct writing achromatic Talbot lithography (DW-ATL) technique for large-area arbitrary sub-micron periodic nano-arrays fabrication. By using a laser interferometer, the sparse hole/dot arrays obtained by ATL could be stitched precisely between discrete multiple exposures. Complex sub-micron periodic nanoarrays, such as elliptical discs, rods, L-shaped and Y-shaped periodic nanoarrays, with a sub-hundred nm resolution were fabricated over an area of ~mm2.

Large-scale Au nanodisk arrays on Si substrate are successfully fabricated via x-ray interference lithography and followed by electron-beam vapor deposition. The Au nanodisk arrays exhibit a significant, uniform, and reproducible surface enhancement on Raman scattering signal, which enables the detection of R6G as low as 10(-8) M with an enhancement factor of 10(6). Importantly, the Au nanodisk arrays SERS-active substrates with uniformly high sensitivity also have high reproducibility and stability. The diameters of the nanodisks and the inter-disk distance can be simply optimized to obtain high enhancement in Raman signal by varying exposure time and development time in XIL process. The electric fields of the Au nanodisks with various diameters and inter-disk distance simulated by the finite difference time domain (FDTD) techniques further confirm that the Raman signal enhancement of Au nanodisks is determined by the diameters of nanodisks and the inter-disk distance of nanodisks. The Au/Ag double-layer bimetal nanodisk arrays are also fabricated which show a significant increase in the Raman signal enhancement than that of the Au nanodisk arrays. XIL nanofabrication appears to be a feasible approach to prepare uniform and reproducible SERS-active substrates with high sensitivity for practical SERS applications.