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Reusability, Long-Life Storage and Highly Sensitive Zirconium Nitride (ZrN) Surface-Enhanced Raman Spectroscopy (SERS) Substrate Fabricated by Reactive Gas-Timing Rf Magnetron Sputtering
(2023-12-22)
Sucheewa, Nguentra
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Wongwiriyapan, Winadda
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Rattanawarinchai, Prapakorn
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Wuttikhun, Tuksadon
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Sinthiptharakoon, Kittiphat
Transition metal nitrides (TMN) are promising material alternative to replace noble metals in the field of plasmonic applications, especially surface-enhanced Raman spectroscopy (SERS). Here we demonstrate a practical surface enhanced Raman spectroscopy (SERS) substrate using zirconium nitride (ZrN) thin films grown by reactive gas-timing (RGT) rf magnetron sputtering. The tailored properties of ZrN thin film exploited for SERS activity could be achieved to obtain a highly sensitive ZrN thin film SERS substrate with the enhancement factor (EF) of 1.24 × 106 and 4.8 %RSD at 1626 cm-1 toward methylene blue (MB) analyte which are comparable to the optimized Au sputtered thin films (EF=1.18 × 106 and with 5.1%RSD). We find that the spatial plasmonic hotspots on the surface of ZrN SERS substrate controlled by the turn-on timing of Ar:N2 sputtered gas sequence, leading to the discrete conductive surface profile, strongly relates to non-stoichiometric composition and the degree of (200)-oriented texture at the surface of ZrN thin film. Furthermore, ZrN thin film SERS substrates exhibit an excellent recyclability more than 30 cycles with simple cleaning process and a storage time longer than 6 months. The detection and reusability of ZrN SERS substrate on the low concentration of trinitrotoluene (TNT) for homeland security are also performed.
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Preparation and Characterization of Low-emissivity AlN/Ag/AlN Films by Magnetron Co-sputtering Method
(2023-09-01)
Phae-Ngam, Wuttichai
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Kamoldilok, Surachart
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Rattana, Tanattha
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Lertvanithphol, Tossaporn
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Mungchamnankit, Araya
AlN and Ag thin films were deposited independently on the Si(100) wafers and glass slides by sputtering technique at various times to find the optimum deposition times for coating AlN and Ag films layers. The results obtained from glazing-incident X-ray diffraction (GIXRD), field-emission scanning electron microscopy (FE-SEM), and transmittance measurements showed that the optimum deposition time for coating AlN and Ag film layers were 40 min and 15 s corresponding to the film thickness of 46.7 and 19.6 nm, respectively. The optimum deposition times were used for coating AlN and Ag films in the multilayer AlN/Ag/AlN film stack. Then, the multilayer AlN/Ag/AlN film stack was deposited on the glass slide for transmittance measurement and a test glass plate with a size of 10 cm x 10 cm for infrared protection testing. The average solar transmittances in the visible range (λ = 380-780 nm) and in the near infrared range (λ = 780-2,000 nm) were found to be 48.05 and 15.17%, respectively which are comparable with those of a commercial glass.
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Tailoring the structural and optical properties of fabricated TiO2 thin films by O2 duty cycle in reactive gas-timing magnetron sputtering
(2023-08-01)
Chittinan, Donyawan
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Buranasiri, Prathan
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Lertvanithphol, Tossaporn
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Eiamchai, Pitak
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Tantiwanichapan, Khwanchai
Titanium dioxide (TiO<inf>2</inf>) thin films were deposited on silicon (100) and glass substrates via conventional reactive sputtering and reactive gas-timing (RGT) sputtering techniques. The duty cycle of supplied O<inf>2</inf> gas determined its effect on the properties of the TiO<inf>2</inf> films through spectroscopic ellipsometry (SE). With the best triple-layer model for SE fitting, the films' structure and optical properties were analyzed and compared. The high-resolution transmission electron microscope (HR-TEM) showed good agreement with the structure of the SE model, while the grazing-incidence X-ray diffraction (GIXRD) confirmed the crystallinity of the films. The results showed that the duty cycle was a crucial factor in the deposition rate and crystalline phase of the TiO<inf>2</inf> films. The optical reflectance (%R) spectra were measured by a UV-VIS-NIR spectrophotometer, representing anti-reflection properties at a specific wavelength related to the duty cycle. Moreover, the omnidirectional optical transmittance (Omni-T) profiles were also determined. The results showed that the transmittances (%T) of TiO<inf>2</inf> film near those specific wavelengths were enhanced over the bare glass substrate at a wide angle. In addition, photoelectron spectroscopy (PES) was used to confirm the chemical states and atomic compositions.
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Structural and Optical Characterizations of Polymethyl Methacrylate Films with the Incorporation of Ultrafine SiO2/TiO2 Composites Utilized as Self-Cleaning Surfaces
(2023-08-01)
Songpanit, Maneerat
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Boonyarattanakalin, Kanokthip
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Limwichean, Saksorn
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Lertvanithphol, Tossaporn
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Horprathum, Mati
The structural and optical characterizations of nanocomposite films of polymethyl methacrylate (PMMA) and SiO<inf>2</inf>/TiO<inf>2</inf> composites prepared via the spin-coating technique were investigated using different SiO<inf>2</inf>:TiO<inf>2</inf> ratios. The SiO<inf>2</inf>/TiO<inf>2</inf> nanocomposites were synthesized using the sonochemical process with Si:Ti precursor ratios of 1:0.1, 1:0.5, 1:1, 1:2, 1:4, and 0:1. All characterizations of ultrafine SiO<inf>2</inf>/TiO<inf>2</inf> particles were loaded at 1 wt.% in a PMMA matrix for the fabrication of transparent SiO<inf>2</inf>/TiO<inf>2</inf>/PMMA composite films. The phase structure and morphology of SiO<inf>2</inf>/TiO<inf>2</inf>/PMMA composite films were monitored using X-ray diffraction, optical microscopy, and field-emission scanning electron microscopy. A surface roughness analysis of SiO<inf>2</inf>/TiO<inf>2</inf>/PMMA nanocomposite films was conducted using atomic force microscopy. For optical characterization, transmission properties with different incident angles of SiO<inf>2</inf>/TiO<inf>2</inf>/PMMA composite films were analyzed with UV-vis spectrophotometry. The water contact angles of SiO<inf>2</inf>/TiO<inf>2</inf>/PMMA composite films were analyzed to identify hydrophilic properties on film surfaces. Photocatalytic reactions in SiO<inf>2</inf>TiO<inf>2</inf> composite films under UV irradiation were evaluated using rhodamine B dye degradation. The optimal condition of SiO<inf>2</inf>/TiO<inf>2</inf>/PMMA nanocomposite films was obtained at a 1:1 SiO<inf>2</inf>:TiO<inf>2</inf> ratio in self-cleaning applications, resulting from good particle dispersion and the presence of the TiO<inf>2</inf> phase in the composite.
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Phase evolution in annealed Ni-doped WO3 nanorod films prepared via a glancing angle deposition technique for enhanced photoelectrochemical performance
(2022-05-15)
Wattanawikkam, Chakkaphan
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Bootchanont, Atipong
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Porjai, Porramain
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Jetjamnong, Chanthawut
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Kowong, Rattanachai
Ni-doped WO<inf>3</inf> nanorod films were fabricated via a reactive magnetron cosputtering with a glancing angle deposition technique. The crystal structure and surface morphology were observed using grazing incident X-ray diffraction and field emission Scanning Electron Microscopy, respectively. The chemical compositions and oxidation state of each element were investigated by X-ray photoemission spectroscopy. The local structure and phase evolution were investigated via X-ray absorption spectroscopy. The local structure of Ni atoms in WO<inf>3</inf> nanorod films is characterized as a NiWO<inf>4</inf> nanocluster in the WO<inf>3</inf> matrix, which is supported by calculated spectra. The phase information obtained after annealing demonstrates that short-length order in amorphous transitions to crystallinity. The phase information of the local structures were acquired and discussed as well as the effect on the annealing process. The coupling of amorphous WO<inf>3</inf>, crystalline WO<inf>3</inf>, and amorphous NiWO<inf>4</inf> exhibits high photoelectrochemical activity of the sample annealed at 400 °C, which was observed with a large current density (2.35 μA/cm<sup>2</sup>) at 1.20 V vs. Ag/AgCl under visible light irradiation, which is greater than that of the unmodified WO<inf>3</inf> photoelectrode (1.38 μA/cm<sup>2</sup>).
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Tailoring Properties of Hafnium Nitride Thin Film via Reactive Gas-Timing RF Magnetron Sputtering for Surface Enhanced-Raman Scattering Substrates
(2022-01-01)
Sucheewa, Nguentra
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Wongwiriyapan, Winadda
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Klamchuen, Annop
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Obata, Michiko
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Fujishige, Masatsugu
This study successfully demonstrated the tailoring properties of hafnium nitride (HfN) thin films via reactive gas-timing (RGT) RF magnetron sputtering for surface-enhanced Raman spectroscopy (SERS) substrate applications. The optimal RGT sputtering condition was investigated by varying the duration time of the argon and nitrogen gas sequence. The RGT technique formed thin films with a grain size of approximately 15 nm. Additionally, the atomic ratios of nitrogen and hafnium can be controlled between 0.24 and 0.28, which is greater than the conventional technique, resulting in a high absorbance in the long wavelength region. Moreover, the HfN thin film exhibited a high Raman signal intensity with an EF of 8.5 × 104 to methylene blue molecules and was capable of being reused five times. A superior performance of HfN as a SERS substrate can be attributed to its tailored grain size and chemical composition, which results in an increase in the hot spot effect. These results demonstrate that the RGT technique is a viable method for fabricating HfN thin films with controlled properties at room temperature, which makes them an attractive material for SERS and other plasmonic applications.
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Spectroscopic ellipsometry study on aluminium-doped zinc oxide thin films prepared via DC magnetron sputtering and HiPIMS
(2019-01-01)
Chittinan, Donyawan
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Lertvanithphol, Tossaporn
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Seawsakul, Kittikhun
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Songsiriritthigul, Prayoon
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Poolcharuansin, Phitsanu
Spectroscopic ellipsometry was used to investigate the properties of aluminium-doped zinc oxide (AZO) thin films deposited on silicon (100) substrate via magnetron sputtering system. The different techniques were used to fabricate including conventional DC magnetron sputtering and high-power impulse magnetron sputtering (HiPIMS). The ellipsometric spectra of the prepared samples were performed in the range of 1.75 to 3.5 eV with 0.025 eV intervals at incident angle of 70 degree. Two different optical models based on Cauchy and Tauc-Lorentz functions were used to fit and compared. The results showed that the Tauc-Lorentz based model was better to fit and extract the properties of interest including thin film thickness and refractive index (n). In addition, the fieldemission scanning electron microscopy (FE-SEM) images were used to confirm the results of thickness and ensure the using of Tauc-Lorentz model.

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