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Rational concept for fully designing metal-oxynitride films through reactive gas-timing magnetron sputtering: A case study on zinc oxynitride film
(2025-08-10)
Khemasiri, Narathon
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Chananonnawathorn, Chanunthorn
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Horprathum, Mati
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Pornthreeraphat, Supanit
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Saekow, Bunpot
Amorphous metal-oxynitride films—particularly zinc oxynitride (ZnON)—are emerging as promising materials for next-generation high-speed switching electronics, due to the absence of a potential barrier above the conduction band, unlike metal-doped ZnO. However, conventional reactive magnetron sputtering often face challenges in precisely controlling in an anion ratio, N/(N + O), because of the different reactivities of nitrogen and oxygen gases. In this work, we present a strategy to precisely control both the crystal structure and N/(N + O) ratio in ZnON films using a reactive gas-timing technique. By adjusting the oxygen gas-timing sequence (t<inf>O₂</inf>), we selectively induce different crystalline phases, which are closely related to the nitridation and oxidation of the sputtered Zn atom/cluster. This technique facilitates effective N incorporation into ZnO, enabling a broad range of N/(N + O) ratios from 0.048 to 0.964 and optical band gap variations from 1.49 eV to 3.22 eV. At an optimal t<inf>O₂</inf>, an amorphous phase is formed, attributed to a balanced nitridation and oxidation rate of the sputtered Zn atom/cluster that suppresses crystallization. The resultant amorphous ZnON film exhibits a high carrier mobility of 84.81 cm²/Vs, which is 1.16-fold and 35.89-fold greater than those of the cubic and hexagonal ZnON films, respectively. Our findings highlight the effectiveness of the reactive gas-timing technique as a powerful tool for the rational design of metal-oxynitride films, paving the way for their application in advanced electronic devices.
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ZnO Nanorods Grown on Heterogenous Ag Seed Layers for Single-Cell Fluorescence Bioassays
(2021-07-23)
Muensri, Phitchaya
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Treetong, Alongkot
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Namdee, Katawut
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Kasamechonchung, Panita
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Wutikhun, Tuksadon
Here we demonstrate the controllability of the morphology of hydrothermal ZnO nanorods (ZnO-NRs) grown on heterogenous Ag seed layers. By varying the crystal orientation of silver thin films (Ag), a high density of ZnO-NRs could be obtained. We find that the density of ZnO-NRs strongly relates to the peak intensity ratio between (111) and (200) planes of Ag thin films due to a heteroepitaxy between (0002) ZnO and (111) Ag rather than that of grain boundary nucleation and/or surface nucleation. In addition, the optimized heterostructure of ZnO nanorod/Ag arrays is investigated via a critical concentration for nucleation and used as a fluorescence enhancement substrate (FES). The experimental results have shown that the FES presents an ability to detect a biological sample (PC-3 cell) with a high sensitivity and low detection limit of 1 cell/μL. Our results highlight that understanding an important key to control and design the morphology of heterogeneous hydrothermal ZnO-NR growth is essential to open up the opportunities for fundamental studies and applications in high-performance integrated nanodevices.
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Size-Independent Unipolar and Bipolar Resistive Switching Behaviors in ZnO Nanowires
(2019-06-15)
Srikimkaew, Oradee
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Suebka, Sartanee
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Sriborriboon, Panithan
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Khemasiri, Narathon
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Kasamechonchung, Panita
In this work, we report on the mixed bipolar and unipolar resistive switching behavior in ZnO nanowires observed through conductive atomic force microscopy measurements on an individual nanowire. Both bipolar and unipolar resistive switching in ZnO nanowires are size-independent, suggesting that the switching is due to conductive filaments with dimensions much smaller than the cross-section of the nanowire. During bipolar resistive switching, both the low resistance and the high resistance states exhibit ohmic conduction at low voltage, consistent with the filament-based model. During unipolar switching, the low-resistance state is a mix of defect-free ohmic conduction and defect-dominated space-charge-limited conduction, which may not be observed in larger devices. Defects also influence transport in the high resistance state, which exhibits trap-controlled space-charge-limited conduction. Our results clearly demonstrate the key role of defects on the resistive switching behavior of ZnO-nanowires, an important consideration for optimizing the material for nonvolatile memory applications.
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Simultaneous activation of copper mixed metal oxide catalysts in alcohols for gamma-valerolactone production from methyl levulinate
(2019-06-05)
Tanwongwan, Worapak
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Eiad-ua, Apiluck
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Kraithong, Wasawat
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Viriya-empikul, Nawin
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Suttisintong, Khomson
Catalytic transfer hydrogenation (CTH)of biomass-derivatives to value-added chemicals using metal-based catalysts is a promising process in biorefinery since it does not require high pressure of expensive and flammable hydrogen gas (H<inf>2</inf>). However, an activation of these catalysts using H<inf>2</inf> treatment prior to the CTH process limits this advantage. Here, copper mixed metal oxides are introduced as simultaneously activated catalysts (SACs)in the presence of alcohol for a production of gamma-valerolactone (GVL)from methyl levulinate (ML)without requirement of additional H<inf>2</inf> gas during both catalyst pretreatment and hydrogenation steps. Different alcohols were selected to function as hydrogen sources for both catalyst activation and ML hydrogenation. All copper mixed metal oxides, especially CuNiO showed significant potential as catalysts for ML conversion to GVL at 200 °C within 3 h. While 2-propanol and 2-butanol exhibited effective roles as hydrogen sources for simultaneous reductions of the catalysts to generate metal active sites and provided hydrogen species for hydrogenation of ML to GVL. Hydrogen temperature programmed reduction (H<inf>2</inf>-TPR), alcohol-assisted simultaneous reaction (ASR), in situ X-ray diffraction (in situ XRD)and X-ray photoelectron spectroscopy (XPS)revealed that the complementary cooperation between secondary alcohols and catalysts is the important key for the high GVL production in this work.
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Effects of thermal treatment on hydrophilicity and corrosion resistance of Ti surface
(2019-03-01)
Boonrungsiman, Suwimon
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Prompinit, Panida
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Khemthong, Pongtanawat
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Wutikhun, Tuksadon
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Treethong, Alongkot
Surface treatment of titanium (Ti) surface has been extensively studied to improve its properties for biomedical applications, including hydrophilicity, corrosion resistance, and tissue integration. In this present work, we present the effects of thermal oxidation as surface modification method on metallic titanium (Ti). The Ti foils were oxidized at 300°C, 400°C, 500°C, and 600°C under air atmosphere for 3 hours, which formed oxide layer on Ti surface. The physicochemical properties including surface chemistry, roughness, and thickness of the oxide layer were evaluated in order to investigate how these factors affected surface hydrophilicity, microhardness, and corrosion resistance properties of the Ti surface. The results revealed that surfaces of all oxidized samples were modified by formation of titanium dioxide layer, of which morphology, phase, and thickness were changed according to the oxidized temperatures. Increasing oxidation temperature led to the formation of thicker oxide layer and phase transformation of anatase to rutile. The presence of the oxide layer helped the improvement of corrosion resistance and microhardness. The most improvement in surface roughness was found in the specimens treated at 400°C, which significantly improved surface hydrophilicity. But both surface roughness and hydrophilicity reduced when oxidized at 500°C and 600°C, suggesting that hydrophilicity was dominated by the surface roughness. In addition, this surface treatment did not reduce the biocompatibility of the metallic Ti substrates against murine osteoblasts (MC3T3).
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Piezoelectric-Induced Triboelectric Hybrid Nanogenerators Based on the ZnO Nanowire Layer Decorated on the Au/polydimethylsiloxane-Al Structure for Enhanced Triboelectric Performance
(2018-02-21)
Jirayupat, Chaiyanut
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Wongwiriyapan, Winadda
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Kasamechonchung, Panita
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Wutikhun, Tuksadon
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Tantisantisom, Kittipong
Here, we demonstrate a novel device structure design to enhance the electrical conversion output of a triboelectric device through the piezoelectric effect called as the piezo-induced triboelectric (PIT) device. By utilizing the piezopotential of ZnO nanowires embedded into the polydimethylsiloxane (PDMS) layer attached on the top electrode of the conventional triboelectric device (Au/PDMS-Al), the PIT device exhibits an output power density of 50 μW/cm<sup>2</sup>, which is larger than that of the conventional triboelectric device by up to 100 folds under the external applied force of 8.5 N. We found that the effect of the external piezopotential on the top Au electrode of the triboelectric device not only enhances the electron transfer from the Al electrode to PDMS but also boosts the internal built-in potential of the triboelectric device through an external electric field of the piezoelectric layer. Furthermore, 100 light-emitting diodes (LEDs) could be lighted up via the PIT device, whereas the conventional device could illuminate less than 20 LED bulbs. Thus, our results highlight that the enhancement of the triboelectric output can be achieved by using a PIT device structure, which enables us to develop hybrid nanogenerators for various self-power electronics such as wearable and mobile devices.
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Texture orientation of silver thin films grown via gas-timing radio frequency magnetron sputtering and their SERS activity
(2016-01-01)
Ukahapunyakul, Pongbordin
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Gridsadanurak, Nurak
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Sapcharoenkun, Chaweewan
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Treetong, Alongkot
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Kasamechonchung, Panita
Here we demonstrate a special technique to control a texture orientation of silver (Ag) thin films using gas-timing (GT) rf magnetron sputtering. By utilizing a GT technique, a dense structure and a high ratio of (111)/(200) of Ag films could be obtained without applying additional energy sources. We found that the GT technique not only provides the ability to adjust the number of sputter species from the target, but also generates the self-energy assisted deposition which related to the atomic peening effect. Furthermore, we found that a high (111)/(200) ratio of Ag films strongly affects the SERS activity of the Ag films due to a hot spot effect. Our results highlight that the texture engineering of metal thin films could be accomplished by using a GT technique.
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Crucial role of reactive pulse-gas on a sputtered Zn3N2 thin film formation
(2016-01-01)
Khemasiri, Narathon
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Chananonnawathorn, Chanunthorn
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Klamchuen, Annop
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Jessadaluk, Sukittaya
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Pankiew, Apirak
Herein, we demonstrate a powerful technique, known as reactive gas-timing (RGT) rf magnetron sputtering, to fabricate high quality Zn<inf>3</inf>N<inf>2</inf> thin films at room temperature without applying any additional energy sources. A single phase of Zn<inf>3</inf>N<inf>2</inf> film formation can only be obtained when a reactive pulse-gas of N<inf>2</inf> is utilized. We find that selecting a small atomic mass of sputtered reactive gas coupled with the pulse-gas technique is very crucial to adjust the number of sputtered atoms obtained from the target and enrich the forming energy of the sputtered Zn<inf>3</inf>N<inf>2</inf> films during the deposition process. Our results highlight that the RGT technique is a promising method to fabricate high quality sputtered compound thin films that can be applied in flexible devices. A simplified model of the materials system at the surface region of the de-nitride Zn<inf>3</inf>N<inf>2</inf> during ion bombardment is also presented.
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Morphology-controlled seed-assisted hydrothermal ZnO nanowires via critical concentration for nucleation and their photoluminescence properties
(2015-01-01)
Kasamechonchung, Panita
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Horprathum, Mati
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Boonpavanitchakul, Kanittha
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Supaka, Nuttapun
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Prompinit, Panida
Here we demonstrate the controllability on morphology of hydrothermal ZnO nanowires through the critical concentration for nucleation. When Zn ion concentration is relatively low, the nucleation process preferentially occurs on the (0001) plane, promoting nanowire growth. In contrast, for relatively high Zn ion concentration, the (10-10) plane emerges, suppressing nanowire growth. The occurrence of this nucleation competition on the crystal planes as a function of concentration is caused by differences in the critical nucleation sizes between the (0001) plane and the (1010) plane. Furthermore, we found that the density of ZnO nanowires trend to decrease with increasing the growth time due to the lateral growth effect. Photoluminescence measurement of ZnO nanowires exhibited that the near band emission peak of 380nm decreased with decreasing nanowire diameter while the broad emission peak below band gap appears the opposite trend because of surface to volume ratio effect.

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