Silver Oxide Thin Films Research Articles

A selective NH3 gas sensor based on (Ag2O)1-x(SnO2)x nanocomposites thin films at various operating temperatures

تم استخدام تقنية ترسيب الليزر النبضي (PLD) للتحضير الأغشية الرقيقة (Ag2O)1-x(SnO2)x النانوية المركبة بنسب مختلفة من x=(0, 0.2,0.4) من النسب الوزنية المرسبة على قواعد زجاجية. تم تلدين الأفلام بعد ذلك في الهواء لمدة ساعتين عند 300 درجة مئوية. تم تأكيد تشكيل المركب (Ag2O)1-x(SnO2)x من خلال تحقيق حيود الأشعة السينية(XRD). وفقًا للفحص المجهري الإلكتروني الماسح (FESEM) ، كانت جزيئات (Ag2O)1-x(SnO2)x التي تم إنشاؤها كروية الشكل. تم أستخدم تحليل مطياف تشتت الاشعة السينية (EDX) لتأكيد العناصر الموجودة في الأفلام المركبة.اظهر تحليل القوة الذرية المجهري (AFM) أن الأفلام الناتجة لها حجم حبيبي بين 37.68 -49.57 نانومتر وخشونة متوسط الجذر التربيعي (RMS ) من 4.92 إلى 8.22 نانومتر. تحتوي الأفلام المحضرة على فجوة طاقة مباشرة بين 2.06 و 3.36 الكترون فولت ، وفقاً لبيانات لبيانات المطياف المرئي للأشعة فوق البنفسجية (UV-Vis) . تم اختبار الأفلام لاستشعار NH3 تحت درجات حرارة تشغيل مختلفة. الاختلافات الملحوظة في مقاومة الغشاء الرقيق لاستجابة استشعار الغاز تدل على الموصلية من النوع n او النوع p عند الغازالمختزل ، تزداد مقاومة أفلام (Ag2O)1-x(SnO2)x عندما تكون x=0, 0.2wt ، مما يشير إلى أن الأفلام من النوع p ، ومع ذلك ، فإن الفيلم الرقيق يعرض السلوك العكسي عندما x = 0.4wt ، مما يشير إلى أنه من النوع n بالإضافة إلى ذلك ، أظهرت جميع الأفلام التي تم إنتاجها حساسية لغاز NH3 بتركيز 95 جزء في المليون. يمتلك الغشاء الرقيق Ag2O حساسية بنسبة 50.5٪ عند درجة حرارة تشغيل 200 درجة مئوية مع أوقات استجابة واسترداد تبلغ 22.5 و 39.6 ثانية على التوالي.علاوة على ذلك أظهرت الأغشية الرقيقة المركبة حساسية أكبرمن الأغشية الرقيقة المصنوعة من أوكسيد الفضة النقي.

Characterization of silver oxide thin films with thickness variation prepared by thermal evaporation method

Thermal evaporation technique has been used to produce silver oxide (AgO). The findings demonstrate that the crystal quality of the AgO film was dominated by the thin and sharp peaks at (111) plans. Atomic Force Microscopy (AFM) confirm that the distribution grains size appears nanostructure and homogeneous in all films. RMS decreased from 6.84 nm to 2.17 nm with thicknesses 200 nm. The surface roughness decreased from 7.82 nm to 3.22 nm. The distribution of grains size appears nanostructured and homogeneous in all films, and a slight decrease in average particle size. The surface displayed that the roughness decreased with the increase in thicknesses. The spectrum fluctuation of their optical constants has been calculated using transmittance and absorption data. In the visible region of the wavelength, all films have a high absorption coefficient with a value of 104 (cm-1 ). According to the optical measurements, the films have a band gap between 1.73 and 1.61 eV. The Extinction coefficient and refractive index drop as film thickness rises.

Structural, morphological, and optical properties of AgxO thin films deposited via obliquely angle deposition

Abstract This work reports on the optical, structural, and morphological properties of silver oxide thin films obtained by postoxidation of silver deposited previously by the thermal evaporation technique. The samples were deposited on glass substrates using the oblique angle deposition technique for different angles of incidence γ (γ=0°, 20°, 40°, 60°, 75°, and 85°). γ is defined as the angle between the particle flux and the normal to the substrate. The resulting thin films were annealed in the free air at two temperatures (300°C and 400°C). X-ray diffraction (XRD), scanning electron microscopy (SEM), and UV-visible-NIR spectrophotometer were performed to study the crystal structure, as well as the morphological and optical properties (transmittance and reflectance), of the AgxO samples. X-ray diffraction analysis revealed the presence of the AgxO phase for the silver films deposited at a high angle of incidence and for the annealing temperature 300°C. In contrast, the diffractograms of the silver films annealed at 400°C show an amorphous behavior. Optical results indicated that the direct band gap energy increases pursuant to increasing the angle of incidence γ. The absorption coefficients of AgxO thin films were found to be in the range of 103–105 cm−1. Additionally, we determined the birefringence for the layers annealed at 400°C and found that the highest value of birefringence is obtained corresponding to the angle of incidence 60°. Morphological analysis indicated that the porosity increases with the angle of incidence and highlights the amorphous nature of the films, which is attributed to the columnar structure.

Effect of reactive gas flow on structural and optical properties of sputtered silver oxide thin films; Kramers-Kronig method

Effect of reactive gas flow on structural and optical properties of sputtered silver oxide thin films; Kramers-Kronig method

The Antimicrobial Activity of Silver Nanoparticles in Ag/Ag2O Composites Synthesized by Oxygen Plasma Treatment of Silver Thin Films

In this work, Ag/Ag2O composites were synthesized by treating silver thin films manufactured by thermal evaporation method with oxygen plasma afterglow. In order to verify the antibacterial behavior of these composites, inhibition zone tests were realized for Staphylococcus aureus. The results showed that individual silver nanoparticles at concentrations that can be controlled by the stoichiometric ratios of the Ag/Ag2O composites, were the main factor in the inhibition of bacteria. In addition, we found that the degree of degradation of individual silver nanoparticles absorption peaks represented a suitable criterion for determining the bacterial inhibition activity of the prepared silver oxide films. The results also showed that the sample treated at 1000 watts gave the highest rate of bacterial inhibition. This research includes an attempt to correlate the bacterial inhibition activity of silver oxide thin films with the structural and spectroscopic properties of these films.

Effect of temperature on the electrochemical performance of silver oxide thin films supercapacitor

The effect of temperature change on the electrochemical performance of silver oxide thin films supercapacitor in an aqueous electrolyte (saline solution), is presented in this paper. Scanning electron microscopy and energy-dispersive X-ray spectroscopy (EDX) were used to probe the morphology and the elemental constituent of the prepared silver oxide thin films. The stoichiometry along with oxide phases of the films were observed with X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The effect of temperature in the range 35 °C to 75 °C, on the electrochemical performance of the films were evaluated by applying electrochemical impedance spectroscopy (EIS), charge-discharge and cyclic voltammetry (CV). The EIS and CV results indicate improved electrochemical performance as operating temperature increases, with an increase in capacitance and reduction in resistance observed. The enhanced electrochemical capacity of the silver oxide thin films with temperature can be attributed to higher ionic conductivity, reduced resistance and faster ion adsorption/desorption at higher temperatures. • XRD reveal that the primary phase is Ag2O • Nyquist plot confirms enhanced mobility of ions at higher temperature • Redox peaks both on the anodic and cathodic sides, are due to Faradaic reactions

Surface morphology and roughness of silver oxide prepared employing pulsed laser at optimum laser fluence

Abstract This paper concerns on preparing a transparent Silver Oxide (Ag2O) thin film using pulsed laser deposition technique. 1.06 μm 7 nm Nd-yag laser with two different laser flounces (47, 53) J/cm2 was used to prepare silver oxide thin films under vacuum condition. Optical, structural and surface morphology was investigated. At the optimum conditions, the optical band gap of the thin film is found to be 3.55 eV with triangle like structure of the surface morphology with 1.61 nm average surface roughness.

Optoelectronic properties of highly porous silver oxide thin film

In this paper, we report oxidation time effect on highly porous silver oxide nanowires thin films fabricated using ultrasonic spray pyrolysis and oxygen plasma etching method. The NW’s morphological, electrical, and optical properties were investigated under different plasma etching periods and the number of deposition cycles. The increase of plasma etching and oxidation time increases the surface roughness of the Ag NWs until it fused to form a porous thin film of silver oxide. AgNWs based thin films were characterized using X-ray diffraction, scanning electron microscope, transmission electron microscope, X-ray photoemission spectroscopy, and UV–Vis spectroscopy techniques. The obtained results indicate the formation of mixed mesoporous Ag2O and AgO NW thin films. The Ag2O phase of silver oxide appears after 300 s of oxidation under the same conditions, while the optical transparency of the thin film decreases as plasma etching time increases. The sheet resistance of the final film is influenced by the oxidation time and the plasma application periodicity.Graphic abstract

The Structural and Optical Properties of Silver Oxide Thin Films Synthesized by Thermal Evaporation of Silver with Subsequent Annealing

In this study, silver oxide thin films were deposited on silicon and glass substrates using thermal evaporation techniques with subsequent annealing in air. The deposited films were annealed in air at different temperatures. The effect of annealing temperature on the structural and optical properties of prepared thin films was investigated. The results showed that, except for the grain size, the annealing temperature has a significant effect on the oxidation rate and the optical properties of silver oxide thin films.

Synthesis and characterization of silver oxide nanoparticles prepared by chemical bath deposition for NH3 gas sensing applications

Nano-silver oxide thin films with high sensitivity for NH3 gas were deposited on glass substrates by the chemical bath deposition technique. The preparations were made under different values of pH and deposition time at 70ᵒ C, using silver nitrate AgNO3 and triethanolamine. XRD analysis showed that all thin films werepolycrystalline with several peaks of silver oxides such as Ag2O, AgO and Ag3O4, with an average crystallite size that ranged between 31.7 nm and 45.8 nm, depending on the deposition parameters. Atomic force microscope (AFM) technique illustrated that the films were homogenous with different surface roughness and thegrain size ranged between 55.69 nm and 86.23 nm. The UV-Vis spectrophotometer showed that the optical direct energy gap ranged between 1.66 eV to 2.12 eV. The silver oxide thin film gives a high sensitivity of 70.12 for NH3 gas at 75°C operating temperature. This study shows that different types of silver oxides can beprepared by the CBD techniques, with the nanostructure to be used in gas sensors and optoelectronic applications.

The Optical Properties of Individual Silver Nanoparticles in Ag/Ag2O Composites Synthesized by Oxygen Plasma Treatment of Silver Thin Films

In this work, we present a more complete description of the optical properties of the silver nanoparticles formed in silver oxide thin films. Ag/Ag2O composites were synthesized by treating silver thin films manufactured by thermal evaporation method with oxygen plasma afterglow. The results showed that exposing silver thin films to oxygen plasma afterglow leads to a monocrystalline structure of silver oxide. Consequently, the relationship between the crystal size and the characteristics of the plasmon optical absorption peaks was studied. A slight degradation of plasmon peaks of the individual silver nanoparticles was observed. We suggested that this degradation might be due to the mutual interaction between the individual silver nanoparticles located near the Ag2O grain shell and the larger silver nanoparticles in neighboring grains. We found that the degree of degradation is related to the Ag2O grain size. On the other hand, the origin of each fluorescence peak in the Raman spectra of the prepared films was determined.

Physicochemical Aspects of the Mechanisms of Rapid Antimicrobial Contact-Killing by Sputtered Silver Oxide Thin Films under Visible Light.

The morphology and band gap of silver oxide thin films have been tuned by radio frequency reactive magnetron sputtering to deposit transparent, visible-light-activated photocatalytic biomaterials with excellent antimicrobial properties. X-ray diffraction, Raman spectroscopy, and X-ray photoelectron spectroscopy using the Ag 3d5/2 and Ag 3d3/2 binding energy peaks have been used to study the chemical composition of the films, and the deposition of two antimicrobial phases of silver oxide, namely, Ag2O and Ag4O4 was confirmed. The optical band gaps of the films were determined by optical spectroscopy and are in the range 2.3 eV (539.6 nm) to 3.2 eV (387.8 nm). Strong transmission of up to 80% was observed in the visible region around 650–750 nm. Silver ion release on the surfaces of the films was monitored using atomic absorption spectroscopy, and sustained silver ion release in both water and saline solution for 24 h was confirmed. Nanocrystallites of sizes between 2.45 and 31.30 nm were observed on the surfaces. The films were challenged with two Gram-positive bacteria (Staphylococcus aureus and Staphylococcus epidermidis) and two Gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa) during antimicrobial activity tests using killing curve analysis with 100% contact killing recorded in 25 and 5 min, respectively. The mechanism of antimicrobial efficacy is suggested to be due to silver ion release, small crystallites, and the ease of ligand replacement in the silver oxide stoichiometry, their exchange and interactions of ligands in the microbe’s biological systems. Our current finding opens the door to furthering the development of visible-light-activated antimicrobial surfaces.

Pseudo-capacitance of silver oxide thin film electrodes in ionic liquid for electrochemical energy applications

Abstract The energy storage potential of silver oxide (Ag2O) thin film electrodes, deposited via radio frequency reactive magnetron sputtering, was investigated in an ionic electrolyte (1-Ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide for supercapacitor applications. X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and Fourier Transform infrared spectroscopy (FTIR) tools were used to evaluate the structural and oxide phases present in the sputtered silver oxide thin film electrodes. The growth mode, morphology, surface area, wettability and surface energy of the deposited nano-structure silver oxide thin films were confirmed by scanning electron microscope (SEM) data, the Brunauer-Emmett-Teller (BET) analysis and by goniometer and tensiometer studies. Furthermore, the ion diffusion, the Faradaic redox reactions and the capacitance of the sputtered thin films exposed to 1-Ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ionic electrolyte, were monitored with electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). The SEM micrographs depict that silver oxide thin films exhibit a columnar growth mode. The wettability analysis reveals that Ag2O thin films are hydrophilic, an indication for excellent electrochemical behaviour. Cyclic voltammetry measurements show that Ag2O thin films exhibit a specific capacitance of 650 F/g at higher sputtering power, demonstrating its promising potential as an active electrode for supercapacitor applications.

Effect of the AgO content on the surface morphology and electrical properties of SnO2 thin films prepared by PLD technique

Tin dioxide doped silver oxide thin films with different x content (0, 0.03, 0.05, 0.07) have been prepared by pulse laser deposition technique (PLD) at room temperatures (RT). The effect of doping concentration on the structural and electrical properties of the films were studied. Atomic Force Measurement (AFM) measurements found that the average value of grain size for all films at RT decrease with increasing of AgO content. While an average roughness values increase with increasing x content. The electrical properties of these films were studied with different x content. The D.C conductivity for all films increases with increasing x content. Also, it found that activation energies decrease with increasing of AgO content for all films. Hall measurements confirmed that all the intrinsic films are n-type charge carriers. The variation of carriers concentration increase with increasing x content. Hall mobility decreasing with increasing x content for all films. Also the variation of Drift velocity, carrier life time and free mean path decrease with increasing of x content.

Electrochemical energy storage of silver and silver oxide thin films in an aqueous NaCl electrolyte

We present an investigation into the pseudo-capacitive energy storage potential of silver (Ag) and silver oxide (Ag2O) thin film electrode materials prepared by reactive magnetron sputtering. The growth mode and morphology of the prepared films were investigated using the scanning electron microscope (SEM), which reveals columnar growth structure and microporous sites.The stoichiometry and oxidation states of the silver oxide films were monitored with X-ray diffraction analysis (XRD), X-ray photoelectron spectroscopy (XPS) and Fourier transform infra-red spectroscopy (FTIR). The XRD results reveal the nano-crystalline nature of the silver and silver oxide thin films with peak intensities indexed at (111) planes.Static and dynamic Contact angle measurements were used to probe the penetration of the aqueous NaCl electrolyte into the pores in the prepared silver and silver oxide films, with surface wettability of all (Ag) and (Ag2O) thin films hydrophilic in nature, which is vital for a good electrochemical performance.The Faradaic redox reactions, capacitance and the charge discharge of the films when exposed to the NaCl electrolyte, were monitored with cyclic voltammetry and chronopotentiometry charge-discharge. Results show that Silver and silver oxide possess specific capacitance of 240.52 F/g and 275.50 F/g at 2 mV/s respectively, which is promising for electrochemical energy storage application.

Effect of sputtering pressure on structural and optical properties of silver oxide thin films; Kramers–Kronig method

Silver oxide nano layers were prepared by RF magnetron sputtering on amorphous SiO2 substrates. O2 pressure in chamber was varied from 1 to 4 and 7 mTorr during growth process. The effects of different O2 pressure on structural, morphological and optical properties of the films were investigated by means of X-ray diffraction, scanning electron microscopy, atomic force microscopy and UV–Vis spectroscopy analyses. Optical reflectance measured in the wavelength of 350–950 nm by spectroscopy. Other optical properties and optical band gaps were calculated using Kramers–Kronig relations. The X-ray diffraction measurements showed change in crystalline structure with increasing O2 pressure. Preferred orientation has been changed to another growth orientation at 4 mTorr O2 pressure. The Atomic force microscope images showed increasing in roughness consistently by increasing oxygen pressure. The thickness of the thin films decreases (from 217 to 180 nm) with increasing O2 pressure. Optical results revealed that the highest optical band gap of 3.1 eV and the highest transmittance of ~ 80% were achieved at lower O2 pressure (1 mTorr).

Investigations of Doping of Sn with Ag2O as a Thin Film on Glass Plate for Morphological Studies

The Sn-doped silver oxide (Ag2O) thin film deposited on well-cleaned microscopic glass plates by Jet Nebulizer Technique was reported in this work. The coated thin film was annealed at 200 and 400 °C temperatures, respectively. The XRD investigation on the thin film at three different temperatures have been carried out and their results showed that, the maximum peak intensity of (200) plane was observed at 400 °C than rest of the two samples. In addition to that, it was also found that, the annealing process has certainly improved the crystallization of the film particularly at 400 °C. The SEM and TEM results confirmed that the particle size in the range of 30–50 nm. The peaks corresponding to the Ag and O in EDAX spectrum ensure the film is purely made up of nano-Ag2O and the presence of Sn was also confirmed by its respective peak. Additionally, vibrational analysis and Raman spectroscopy was carried out in this work to confirm the modes of vibration of the NPs. Sensitivity analyses was carried out to test the sensing capacity of the powder.

Controlled oxidation state of silver oxide thin films deposited by an integrated anode layer ion source ion beam sputter module

Abstract An integrated ion beam sputter deposition module utilizing an anode layer ion source has been designed and fabricated. Silver oxide is deposited utilizing this ion beam sputter module. Experimental results show that Ag is fully oxidized only with oxygen partial flow rate equal to and higher than 0.8. With an anode voltage of 700 V, silver oxide with (1 1 1) preferred orientation was obtained. Increasing anode voltage to 1500 V results in (2 0 0) orientated silver oxide thin films. Two band gaps can be identified that increase from 1.0/2.6 eV to 2.0/2.8 eV as anode voltage increases from 700 to 1500 V, respectively. As anode voltage increases, XPS analysis shows that Ag 3d5/2 core level peak position shifts from 367.3 to 367.7 eV. This confirms that increased kinetic energy of sputtered atoms results in partial reduction of AgO to Ag2O. Fully oxidized silver oxide samples are likely to be p-type while the resistivity is in the range of 0.7–2.0 × 104 Ω·cm.

Relative SHG measurements of metal thin films: Gold, silver, aluminum, cobalt, chromium, germanium, nickel, antimony, titanium, titanium nitride, tungsten, zinc, silicon and indium tin oxide

We have experimentally measured the surface second-harmonic generation (SHG) of sputtered gold, silver, aluminum, zinc, tungsten, copper, titanium, cobalt, nickel, chromium, germanium, antimony, titanium nitride, silicon and indium tin oxide thin films. The second-harmonic response was measured in reflection using a 150fs p-polarized laser pulse at 1561nm. We present a clear comparison of the SHG intensity of these films relative to each other. Our measured relative intensities compare favorably with the relative intensities of metals with published data. We also report for the first time to our knowledge the surface SHG intensity of tungsten and antimony relative to that of well known metallic thin films such as gold and silver.

Analysis of temporal evolution of quantum dot surface chemistry by surface-enhanced Raman scattering.

Temporal evolution of surface chemistry during oxidation of silicon quantum dot (Si-QD) surfaces were probed using surface-enhanced Raman scattering (SERS). A monolayer of hydrogen and chlorine terminated plasma-synthesized Si-QDs were spin-coated on silver oxide thin films. A clearly enhanced signal of surface modes, including Si-Clx and Si-Hx modes were observed from as-synthesized Si-QDs as a result of the plasmonic enhancement of the Raman signal at Si-QD/silver oxide interface. Upon oxidation, a gradual decrease of Si-Clx and Si-Hx modes, and an emergence of Si-Ox and Si-O-Hx modes have been observed. In addition, first, second and third transverse optical modes of Si-QDs were also observed in the SERS spectra, revealing information on the crystalline morphology of Si-QDs. An absence of any of the abovementioned spectral features, but only the first transverse optical mode of Si-QDs from thick Si-QD films validated that the spectral features observed from Si-QDs on silver oxide thin films are originated from the SERS effect. These results indicate that real-time SERS is a powerful diagnostic tool and a novel approach to probe the dynamic surface/interface chemistry of quantum dots, especially when they involve in oxidative, catalytic, and electrochemical surface/interface reactions.