Saksorn Limwichean

Fabrication and Characterization of Antibacterial Ag-TiO2 Thin Films Prepared by DC Magnetron Co-Sputtering Technique

In this study, silver-doped titanium dioxide (Ag-TiO2) thin films were prepared co-sputtering technique in order to promote photo-induced antibacterial applications. The high-purity Ag (99.995%) and Ti (99.995%) were simultaneously co-sputtering on BK7 glass and silicon (100) wafers substrate. The structure, morphology, surface roughness and optical properties were characterized by grazing-incidence X-ray diffraction (GIXRD), field-emission scanning electron microscopy (FE-SEM) and UV-Vis spectrophotometer, respectively. The results showed that the as-deposited Ag-TiO2 thin films had high transparency in the visible range. The antibacterial activity was studied in the presence and in the absence of UV irradiation against Escherichia coli as a model for Gram-negative bacteria. The results indicated that, in comparison to conventional TiO2 films, the Ag-TiO2 thin films exhibited excellent antibacterial properties under the UV illumination.

Tuberculosis determination using SERS and chemometric methods

Nanostructures have been multiplying the advantages of Raman spectroscopy and further amplify the advantages of Raman spectroscopy is a continuous effort focused on the appropriate design of nanostructures. Herein, we designed different shapes of plasmonic nanostructures such as Vertical, Zig Zag, Slant nanorods and Spherical nanoparticles employing the DC magnetron sputtering system as SERS-active substrates for ultrasensitive detection of target molecules. The fabricated plasmonic nanostructures sensitivity and uniformity were exploited by reference dye analyte. These nanostructures were utilized in the label free detection of infectious disease, Tuberculosis (TB). For the first time, TB detection from serum samples using SERS has been demonstrated. Various multivariate statistical methods such as principal component analysis, support vector machine, decision tree and random forest were developed and tested their ability to discriminate the healthy and active TB samples. The results demonstrate the performance of the SERS spectra, chemometric methods and potential of the method in clinical diagnosis.

Effect of Oxygen Flow Rate and Post Annealing on Vanadium Oxide Thin Films Prepared by DC Pulse Magnetron Sputtering

In this work, we investigated V2O5 thin films prepared by a DC pulse reactive magnetron sputtering at ambient conditions. The effects of oxygen flow rates during the film deposition and post annealing in air atmosphere were explored. The V2O5 thin films were sputtered from vanadium target onto silicon wafer and glass slide substrates at room temperature. The as-deposited V2O5 thin films were annealed at 200°C under air atmosphere. The films were then examined for their crystallinity, physical microstructures, and optical transmission. The crystallinity and morphology of the films were investigated by grazing incident x-ray diffraction, atomic force microscopy, and field-emission scanning electron microscopy. The optical transmission was determined by UV-Vis Spectrophotometer. The results showed that the as-deposited films were amorphous, whereas the post annealed films indicated V2O5 phase in all samples. The increase in the oxygen flow rates during the deposition led to the decrease in the deposition rate, film thickness, and film surface roughness. In addition, the oxygen flow can increase the average transmission of the V2O5 thin films. The effects of the annealing treatment of the optical transmission spectra will be discussed.

Applications of surface-enhanced Raman scattering (SERS) substrate

Threats of explosive, toxic and narcotic substances continue growing importance to a number of places around the world. In many recent cases, the treats are coming from unprecedented well-funded, increasing sophisticated and highly mass propaganda of radical or criminal organizations. These are challenging tasks for the defense agencies to implement new technologies and methods to ramp up intelligence gathering and visibility in order to pinpoint and deactivate the threats at multiple levels. Some of the main challenges are to develop faster, more sensitive, less expensive portable systems to facilitate the ultra-low detection of the targeted chemical compounds for anti-terror/criminal purposes. This article is to review the progress of surface-enhanced Raman scattering (SERS) substrate of silver nanorod fabricated by magnetron sputtering technique, developed by our group at NECTEC for defense related applications, which have been published in several previous reports, in order to promote the technique as a major tool for rapid identification of such terror/criminal substances at ultra - sensitive levels. Major highlights are trace detection of several toxic organophosphorous compounds, explosives including TNT and commercial explosives and a narcotic drug based on methamphetamine - at a sensitivity that can compete with, or even better than, conventional methods.

Controllable decoration of Au NPs on zinc oxide nanorods template by magnetron sputtering technique for reusable-SERS active surface enhancement

Surface Enhanced Raman Scattering (SERS) is a new invention developed to expand the Raman signal. The SERS chip has a performance to enhance the Raman signal up to a million times. Nevertheless, the chip has some disadvantages which are high cost and it is disposable device. In this research, the controllable decoration of gold nanoparticles on zinc oxide nanorods template for a reusable SERS chip is investigated. Time periods to decorate gold particles are controlled by using DC magnetron sputtering technique from 15 to 450 s. The zinc oxide nanostructures are grown by hydrothermal. The physical structures of the reusable SERS chip are analyzed by Field Emission Scanning Electron Microscope (FE-SEM). The sizes and thicknesses of the gold particles attached to the ZnO nanorods are measured from FE-SEM images. The efficiency to amplify Raman signal of the reusable SERS chip is tested by dropping methylene blue (MB). UV light is used to activate self-cleaning property of the reusable SERS chip. From the results, sputtering gold nanoparticles for 270 s shows the highest performance to amplify Raman signal of methylene blue, up to 1 × 10−6 M, however; it takes 450 minutes of UV cleaning before reuse again. On the other hand, sputtering gold nanoparticles for 15 s shows the fastest clean surface after UV cleaning, though the chip can amplify the Raman signal up to 1×10−5 M.Surface Enhanced Raman Scattering (SERS) is a new invention developed to expand the Raman signal. The SERS chip has a performance to enhance the Raman signal up to a million times. Nevertheless, the chip has some disadvantages which are high cost and it is disposable device. In this research, the controllable decoration of gold nanoparticles on zinc oxide nanorods template for a reusable SERS chip is investigated. Time periods to decorate gold particles are controlled by using DC magnetron sputtering technique from 15 to 450 s. The zinc oxide nanostructures are grown by hydrothermal. The physical structures of the reusable SERS chip are analyzed by Field Emission Scanning Electron Microscope (FE-SEM). The sizes and thicknesses of the gold particles attached to the ZnO nanorods are measured from FE-SEM images. The efficiency to amplify Raman signal of the reusable SERS chip is tested by dropping methylene blue (MB). UV light is used to activate self-cleaning property of the reusable SERS chip. From the res...

Transparent conductive nanocolumnar AZO film coating by glancing angle deposition technique

In this work, we deposited nanocolumnar aluminum doped zinc oxide (AZO) film by glancing angle deposition (GLAD) to produce transparent conductive oxide (TCO) film with omnidirectional antireflecti...

Omnidirectional antireflection and electrochromic properties of WO3 nanorods prepared by oblique angle deposition

In this study, the electrochromic tungsten oxide (WO3) nanorods were successfully prepared by reactive dc magnetron sputtering with oblique angle deposition (OAD) technique on silicon (100) wafer, glass slide and ITO coated glass substrates. The influence of sputtering power on the WO3 nanorods were investigated by grazing incident X-ray diffractometer, field emission scanning electron microscope and spectrophotometer. The thickness of the WO3 nanorods layer was controlled at 400 nm by adjusting the deposition time in order to optimize the electrochromic property. These WO3 nanorods had an amorphous and high transmittance with omnidirectional antireflection property. In addition, the prepared electrochromic WO3 nanorods sample were also shown high optical contrast which demonstrated considerable potential in the smart window application.In this study, the electrochromic tungsten oxide (WO3) nanorods were successfully prepared by reactive dc magnetron sputtering with oblique angle deposition (OAD) technique on silicon (100) wafer, glass slide and ITO coated glass substrates. The influence of sputtering power on the WO3 nanorods were investigated by grazing incident X-ray diffractometer, field emission scanning electron microscope and spectrophotometer. The thickness of the WO3 nanorods layer was controlled at 400 nm by adjusting the deposition time in order to optimize the electrochromic property. These WO3 nanorods had an amorphous and high transmittance with omnidirectional antireflection property. In addition, the prepared electrochromic WO3 nanorods sample were also shown high optical contrast which demonstrated considerable potential in the smart window application.

Hydrothermal Growth of ZnO Nanorods along the Ultra-Thin ZnO Seed Layer Prepared by Magnetron Sputtering

ZnO nanorods were grown on magnetron sputtered ultra-thin ZnO seed layers through a hydrothermal method. Before ZnO nanorods growth, the ultra-thin ZnO seed layer has been annealed at temperatures ranging from 100 to 400°C in air. The influence of annealing treatment on the crystalline structure of the ultra-thin ZnO seed layers has been investigated by X-ray diffraction (XRD). The size and density of final prepared ZnO nanorods were investigated by field-emission scanning electron microscopy (FE-SEM). It was found that the length and the aspect ratio of the ZnOnanorods can be readily tuned by control of the ZnO ultra-thin seeds layer which results from the annealing treatment process.

Influence of Growth Conditions on Morphology of ZnO Nanorods by Low-Temperature Hydrothermal Method

Zinc oxide (ZnO) nanorods (NRs) promise high potentials in several applications, such as photovoltaic device, thermoelectric device, sensor and solar cell. In this research, the vertical alignment of ZnO NRs was fabricated by hydrothermal method with various precursor concentrations and growth time on different seed layers (ZnO and Au), which deposited on silicon wafer substrate (100). The crystalline structure and morphology of ZnO NRs have been characterized by x-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM) techniques, respectively. The x-ray diffraction pattern shows that the prepared samples have a strong preferred orientation (002) plane. FE-SEM images of the ZnO NRs, it found that the density and aspect ratio were strongly influenced by the seed layer and precursor concentration. In addition, the aspect ratio of ZnO NRs was increased with increasing growth time. This study provides a cost effective method for the fabrication of well aligned ZnO NRs for nano-electronic devices.

Spectroscopic Ellipsometry Analyses on Plasma Treatment of Aluminium Oxide Thin Film

Spectroscopic Ellipsometry (SE) was used to analyse the effect of plasma treatment on aluminium oxide thin films. The aluminium oxide thin films were fabricated by reactive DC magnetron sputtering at different operating pressures. The as-deposited thin films were plasma treated at different ambient Ar and O2 conditions. The prepared samples were investigated for physical microstructures with scanning electron microscopy (SEM) and optical characteristics with ellipsometry. The ellipsometric spectra of the prepared samples were measured in the range of 250 to 1650 nm with the incidence angle of 70 degree. Based on the optical model with the Tauc-Lorentz function, the thickness and the refractive index of the films were determined and discussed. The results showed that the thickness and the refractive index of the aluminium oxide thin films were greatly affected after the plasma treatments. In comparison, the results of those prepared at different operating pressures were also discussed. The SE results were confirmed with those from SEM.