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Formation of HfOxNy nanorod GLAD films growth by rapid thermal oxidation
(2023-01-01)
Phae-ngam, W.
;
Prathumsit, J.
;
Chananonnawathorn, C.
;
Nakajima, H.
;
Lertvanithphol, T.
In this work, the hafnium oxynitride (HfON) nanorod films on p-type silicon (Si) wafer substrate have been fabricated by reactive magnetron sputtering with glancing angle deposition (GLAD) technique, subsequently with a rapid thermal oxidation process at 500–900 °C under low-vacuum state. The crystallinity and morphology were investigated by glazing-incident X-ray diffraction (GIXRD) and field-emission scanning electron microscopy (FE-SEM), respectively. As-deposited films were amorphous nanorod films. The surface-sensitive X-ray photoelectron spectroscopy (XPS) analytical technique revealed that nitrogen atoms are increasingly replaced with oxygen atoms at the surface. The distribution of nitrogen atoms investigated by X-ray absorption spectroscopy (XAS) revealed the substitution of nitrogen with oxygen at the film surface and molecular nitrogen trapped in the film as the annealing temperature was increased.
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Spectroscopic study on amorphous tantalum oxynitride thin films prepared by reactive gas-timing RF magnetron sputtering
(2019-10-30)
Lertvanithphol, T.
;
Rakreungdet, W.
;
Chananonnawathorn, C.
;
Eiamchai, P.
;
Limwichean, S.
The amorphous tantalum oxynitride (TaO<inf>x</inf>N<inf>y</inf>) thin films were prepared on silicon (100) substrates by magnetron sputtering system with different techniques of conventional reactive sputtering and reactive gas-timing (RGT). The films were studied via spectroscopic ellipsometry (SE) measured in the range of 0.75–5.0 eV with 0.025 eV interval at 70° incident angle, and the optical model based on Tauc-Lorentz function was constructed to extract the properties of the films. The SE results indicated that all prepared films were grown homogeneously and show different optical properties upon their deposition conditions and techniques. The optical properties of film prepared by conventional reactive sputtering were close to the tantalum oxide film (TaO). The refractive index and optical band gap (E<inf>g</inf>) of RGT samples changed with the oxygen timing and correlated with the change of oxygen and nitrogen concentration of the films. In addition, the morphologies, crystallinities, atomic concentrations and distributions of nitrogen atoms in the films analyzed by field-emission scanning electron microscopy, glazing-incident X-ray diffraction, X-ray photoelectron spectroscopy and X-ray absorption spectroscopy are also discussed.
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Observations of the initial stages on reactive gas-timing sputtered TaO thin films by dynamic in situ spectroscopic ellipsometery
(2019-06-01)
Chittinan, D.
;
Buranasiri, P.
;
Lertvanithphol, T.
;
Eiamchai, P.
;
Patthanasettakul, V.
Dynamic in-situ spectroscopic ellipsometry (iSE) was employed to investigate the growth mechanism of the tantalum oxide (TaO) film on silicon wafer substrate deposited by reactive gas-timing RF magnetron sputtering compared with conventional reactive sputtering. The effect of reactive gas timing parameter on physical structure and optical property were analyzed by both the continuous and island film growth model with Tauc-Lorentz optical model. The variation of refractive index, film thickness and void volume fraction were obtained from dynamic fits of iSE data indicated that the growth process of the amorphous TaO thin films was divided into two regimes: the nucleation stage and continuous-layer stage. These stages were observed during deposition although the initial film growth stage corresponds to the island film growth model. The study demonstrates that sputtered TaO by the RGT technique at the O<inf>2</inf> on-off gas timing has played a crucial factor in improving the formation of nucleation stage and that the deposited TaO thin films were high deposition rate with high refractive index. The complementary field emission scanning electron microscope (FE-SEM) and transmission electron microscope (TEM) showed a good agreement with the film thickness and morphology obtained from dynamic iSE measurement. The real-time monitoring of iSE offers important evidences to understand the growth mechanism of reactive gas-timing technique.
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Omnidirectional anti-reflection properties of vertically align SiO2 nanorod films prepared by electron beam evaporation with glancing angle deposition
(2018-01-01)
Prachachet, R.
;
Samransuksamer, B.
;
Horprathum, M.
;
Eiamchai, P.
;
Limwichean, S.
Omnidirectional anti-reflection coating nanostructure film have attracted enormous attention for the developments of the optical coating, lenses, light emitting diode, display and photovoltaic. However, fabricated of the omnidirectional antireflection nanostructure film on glass substrate in large area was a challenge topic. In the past two decades, the invention of glancing angle deposition technique as a growth of well-controlled two and three-dimensional morphologies has gained significant attention because of it is simple, fast, cost-effective and high mass production capability. In this present work, the omnidirectional anti-reflection nanostructure coating namely silicon dioxide (SiO<inf>2</inf>) nanorods has been investigated for optimized high transparent layer at all light incident angle. The SiO<inf>2</inf> nanorod films of an optimally low refractive index have been fabricated by electron beam evaporation with the glancing angle deposition technique. The morphological of the prepared sampled were characterized by field-emission scanning electron microscope (FE-SEM) and high-resolution transmission electron microscope (HRTEM). The optical transmission and omnidirectional property of the SiO<inf>2</inf> nanorod films were investigated by UV-Vis-NIR spectrophotometer. The measurement were performed at normal incident angle and a full spectral range of 200 - 2000 nm. The angle dependent transmission measure were investigated by rotating the specimen, with incidence angle defined relative to the surface normal of the prepared samples. The morphological characterization results showed that when the glancing angle deposition technique was applied, the vertically align SiO<inf>2</inf> nanorods with partially isolated columnar structure can be constructed due to the enhanced shadowing and limited addtom diffusion effect. The average transmission of the vertically align SiO<inf>2</inf> nanorods were higher than the glass substrate reference sample over the visible wavelength range at all incident angle due to the transition in the refractive index profile from air to the nanostructure layer that improved the anti-reflection characteristics.
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A comparative study on omnidirectional anti-reflection SiO2 nanostructure films coating by glancing angle deposition
(2018-01-01)
Prachachet, R.
;
Samransuksamer, B.
;
Horprathum, M.
;
Eiamchai, P.
;
Limwichean, S.
Fabricated omnidirectional anti-reflection nanostructure films as a one of the promising alternative solar cell applications have attracted enormous scientific and industrial research benefits to their broadband, effective over a wide range of incident angles, lithography-free and high-throughput process. Recently, the nanostructure SiO<inf>2</inf> film was the most inclusive study on anti-reflection with omnidirectional and broadband characteristics. In this work, the three-dimensional silicon dioxide (SiO<inf>2</inf>) nanostructured thin film with different morphologies including vertical align, slant, spiral and thin films were fabricated by electron beam evaporation with glancing angle deposition (GLAD) on the glass slide and silicon wafer substrate. The morphological of the prepared samples were characterized by field-emission scanning electron microscope (FE-SEM) and high-resolution transmission electron microscope (HRTEM). The transmission, omnidirectional and birefringence property of the nanostructure SiO<inf>2</inf> films were investigated by UV-Vis-NIR spectrophotometer and variable angle spectroscopic ellipsometer (VASE). The spectrophotometer measurement was performed at normal incident angle and a full spectral range of 200 - 2000 nm. The angle dependent transmission measurements were investigated by rotating the specimen, with incidence angle defined relative to the surface normal of the prepared samples. This study demonstrates that the obtained SiO2 nanostructure film coated on glass slide substrate exhibits a higher transmission was 93% at normal incident angle. In addition, transmission measurement in visible wavelength and wide incident angles -80 to 80 were increased in comparison with the SiO2 thin film and glass slide substrate due to the transition in the refractive index profile from air to the nanostructure layer that improve the antireflection characteristics. The results clearly showed the enhanced omnidirectional and broadband characteristic of the three dimensional SiO2 nanostructure film coating.
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Optical band engineering of metal-oxynitride based on tantalum oxide thin film fabricated via reactive gas-timing RF magnetron sputtering
(2016-11-25)
Khemasiri, N.
;
Jessadaluk, S.
;
Chananonnawathorn, C.
;
Vuttivong, S.
;
Lertvanithphol, T.
In this paper, we demonstrate a novel technique, as called reactive gas-timing (RGT) RF magnetron sputtering, to control and design an optical band engineering of TaON thin films without an external heating substrate temperature and post annealing treatment process. The influence of the oxygen intervals ranged from 5 to 60 s on deposition rate, chemical composition and optical properties of TaON thin films were investigated. The chemical composition was characterized by auger electron spectroscopy (AES). The optical properties were determined by UV–Vis spectrophotometer and spectroscopic ellipsometry. The nitrogen atomic concentration of the TaON thin films deposited by RGT decreased when the oxygen gas-timing intervals increased. In addition, the RGT sputtered TaON films could be demonstrated band gaps engineering from 1.90 to 2.15 eV.
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Tantalum oxide bio-photonics thin film grown by gas-timing innovation technique
(2013-09-18)
Khemasiri, N.
;
Porntheeraphat, S.
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Horprathum, M.
;
Chananonnawathorn, C.
;
Bunjongpru, W.
Tantalum oxide (TaxOy) as high refractive index material has been grown on p-type silicon and quartz substrates by R.F. magnetron sputtering with our innovative technique called "reactive-gas timing". The reactive gas timing technique is an on-off time period sequence between argon (Ar) and oxygen (O2) plasma during sputtering process. The technique of gas-timing plays the effect on the properties of TaxOy thin film. The bombarded Ar-plasma was varied at 2, 5 and 8 sec, while the period of reactive O2-plasma was kept at 5 sec in this experiment. The physical and optical properties were investigated by using X-ray diffraction (XRD), Atomic Force Microscope (AMF), UV-Visible spectrometer and Spectroscopic Ellipsometer, respectively. The XRD spectra and AFM photographs show all films are amorphous phase with smooth feature. Meanwhile the transmittance of sputtered thin film decreases with 10% and the absorption edge shifts to lower energy with the increasing of the argon period from 2 sec to 8 sec. The refractive index as showed by ellipsometry slightly increases from 2.08 to 2.17 at wavelength 550 nm with the increasing of argon period from 2 sec to 8 sec. The increasing of the refractive index might dues to tantalum (Ta) rich which consists in thin films. The Ar-plasma period in the deposited film plays an important role on the properties of the TaxOy thin films especially as optical refractive index material. © 2013 SPIE.

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