A systematic review, covering fabrication of nanoscale patterns by laser interference lithography (LIL) and their applications for optical devices is provided. LIL is a patterning method. It is a simple, quick process over a large area without using a mask. LIL is a powerful technique for the definition of large-area, nanometer-scale, periodically patterned structures. Patterns are recorded in a light-sensitive medium that responds nonlinearly to the intensity distribution associated with the interference of two or more coherent beams of light. The photoresist patterns produced with LIL are the platform for further fabrication of nanostructures and growth of functional materials used as the building blocks for devices. Demonstration of optical and photonic devices by LIL is reviewed such as directed nanophotonics and surface plasmon resonance (SPR) or large area membrane reflectors and anti-reflectors. Perspective on future directions for LIL and emerging applications in other fields are presented.

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Carbon nanotubes (CNT) are extremely sensitive to environmental gases. However, detection of mixture gas is still a challenge. Here, we report that 10 ppm of carbon monoxide (CO) and ammonia (NH3) can be electrically detected using a carboxylic acid-functionalized single-walled carbon nanotubes (C-SWCNT). CO and NH3 gases were mixed carefully with the same concentrations of 10 ppm. Our sensor showed faster response to the CO gas than the NH3 gas. The sensing properties and effect of carboxylic acid group were demonstrated, and C-SWCNT sensors with good repeatability and fast responses over a range of concentrations may be used as a simple and effective detection method of CO and NH3 mixture gas.

Nanoscale patterns are fabricated by laser interference lithography (LIL) using Lloyd's mirror interferometer. LIL provides a patterning technology with simple, quick process over a large area without the usage of a mask. Effects of various key parameters for LIL, with 257 nm wavelength laser, are investigated, such as the exposure dosage, the half angle of two incident beams at the intersection, and the power of the light source for generating one or two dimensional (line and dot) nanoscale structures. The uniform dot patterns over an area of 20 mm x 20 mm with the half pitch sizes of around 190, 250, and 370 nm are achieved and by increasing the beam power up to 0.600 mW/cm2, the exposure process time was reduced down to 12/12 sec for the positive photoresist DHK-BF424 (DongJin) over a bare silicon substrate. In addition, bottom anti-reflective coating (DUV-30J, Brewer Science) is applied to confirm improvements for line structures. The advantages and limitations of LIL are highlighted for generating nanoscale patterns.

3482www.MaterialsViews.com wileyonlinelibrary.com gate bias stress during most of the driving time and transparent devices are exposed to ambient light unavoidably. The stability resulting from electrical stress under light illumination is important since it can deteriorate the switching performances of a-IGZO-based TFTs. It was found that the positive bias illumination stress is insignifi cant compared to the negative bias illumination stress (NBIS). [ 7 ] NBIS has been explained by photo-induced carriers and the state transition, [7][8][9][10] but the exact mechanism is under debate. In addition, previous reports to improve the stability from NBIS are still insuffi cient from a device viewpoint.Herein we report a more practical use of a-IGZO-based TFTs by adopting plasmonic fi lters (PFs). Metal structures at the submicron scale demonstrate a unique optical response known as a surface plasmon (SP). A metallic fi lm with two dimensional nanohole arrays shows high transmission at the SP resonance frequency and the optical response related to this resonance phenomenon can be easily designed by the material and geometrical factors. This structural coloring technology using thin metal fi lms is superior in fi ltering performance compared to the conventional dye-based color fi lter that experiences degradation by heat and light due to the low chemical stability of the organic-dye material. In addition, thin and quasi-planar structures are advantageous in that they can be easily integrated with other devices. Therefore, PFs have recently been highlighted for use in industrial imaging applications such as CMOS image sensors and displays. [ 11,12 ] With this point of view, we suggest a novel AOS device that has possible applications in transparent electronics, by integrating a-IGZO-TFTs and PFs. A study on NBIS of the suggested a-IGZO-TFTs combined with PFs was performed. Unlike previous work with white or a monochromatic light source, the photosensitivity of a-IGZO-TFTs was investigated with the selectively controlled spectral range of the illumination by the PFs. The suggested TFTs showed extremely improved stability even under a NBIS environment. In addition, compared to the prior AOS TFTs which were equipped with equipped with metal shielding layer to block the light, [ 13 ] our suggestion provides not only the spectral selectivity from the light source but also reduces in the loss of transparency. We expect that the photosensitivity subdivided into spectral ranges will provide a practical guideline for designing structures or a fabrication process of transparent devices and enlarge the usage of AOS TFTs.Optical Characteristics of Plasmonic Filters : One of a prominent optical phenomena of nanohole arrays compared to that of micron scaled structures is extraordinary optical transmission [+] These authors contributed equally to this work. Photo-Insensitive Amorphous Oxide Thin-Film Transistor Integrated with a Plasmonic Filter for Transparent ElectronicsRecently, research interests in amorphous oxide semiconducto...