Aluminum-doped Zinc Oxide Layer Research Articles

Atomic layer deposition of aluminum-doped zinc oxide onto MoO3 nanorods toward enhanced lithium storage performance

An atomic layer deposition (ALD) of aluminum-doped zinc oxide (AZO) onto MoO3 nanorods (denoted as MoO3@AZO) was developed to enhance the lithium storage performance of MoO3 anode. Thanks to the highly conductive and robust AZO layer, the MoO3@AZO electrode demonstrated high pseudocapacitive contribution (76.2 % at 1.0 mV s−1), enhanced electron/ion transferability, outstanding rate performance (708 mAh g−1 at 2 A g−1) and excellent cycling stability (973 mAh g−1 after 100 cycles at 0.2 A g−1 with a high capacity retention of 92.8 %) when applied as an anode for lithium-ion batteries. Ex-situ transmission electron microscopy analysis revealed that the rod feature of MoO3@AZO was well retained with the protection of the AZO layer even after 100 cycles. Moreover, the ALD-AZO coating may also be commonly used for other metal oxides to enhance their electron conductivity and structural stability.

Enhanced UV Absorption By 2D MoS2 Nanoparticles

MoS2 is one of the promising 2D materials that caught the interest of many research fields[1], [2] due to their size-dependent tunable bandgap and attractive magnetic, optical, and electrical properties[3]. Furthermore, recently there has been a growing interest in utilizing MoS2 for solar cell applications that demonstrated measurable device enhancements[4]–[6]. Hence, there is a great interest in understanding its potential for solar energy harvesting. In this study, we show a simple method to deposit a 2D layer of MoS2 nanoparticles (NPs) on top of Aluminum-doped Zinc oxide (AZO) layer (transparent conductive oxide) and investigate its spectral response and potential for application in optoelectronic systems.A thin film of 80 nm AZO layer was grown on a 4-inch quartz wafer using thermal Atomic Layer Deposition (ALD) with a 1:19 ratio which has shown good electrical and optical qualities for solar cell applications[7]. We deposited the MoS2 by spin-coating it on the AZO/quartz wafers for 40 sec at 1000 rpm. Incremental coating is carried on by dispersing seven layers with 500 μL of MoS2 in each step using a precise pipet to a cumulative dispersion volume of 3500 μL. The prepared samples were characterized using a UV-Vis-NIR spectrometer (Perkin Elmer Lambda) across a wide range of wavelengths (250-1200 nm) by measuring both transmittance and reflectance and calculating absorbance. Furthermore, the base AZO/quartz and quartz background signal were measured before spin-coating as reference.The obtained data shows a high absorbance effect due to MoS2 NPs at low wavelengths (<400 nm), where it peaks around 340 nm with an approximate absorbance of ~6.7%. Upon further examination, we notice that this behavior is not linear across the whole spectrum and instead is a function of (i) wavelength and (ii) MoS2 quantity which could be partially due to the quantum confinement effect of several layers of stacked 3D MoS2 nanoparticles[8]. This phenomenon could open the possibility of utilizing this material for low-wavelength filters or UV sensing applications[9]. Also, it can potentially be utilized for quantum down-conversion[10] of high-energy photons to re-emit photons at lower energies in order to enhance solar cells’ efficiencies and reduce thermal burden; however, further investigation is needed.[1] P. Zhou, C. Chen, X. Wang, B. Hu, and H. San, “2-Dimentional photoconductive MoS2 nanosheets using in surface acoustic wave resonators for ultraviolet light sensing,” Sensors and Actuators A: Physical, vol. 271, pp. 389–397, Mar. 2018, doi: 10.1016/j.sna.2017.12.007.[2] H. Dong et al., “Fluorescent MoS 2 Quantum Dots: Ultrasonic Preparation, Up-Conversion and Down-Conversion Bioimaging, and Photodynamic Therapy,” ACS Appl. Mater. Interfaces, vol. 8, no. 5, pp. 3107–3114, Feb. 2016, doi: 10.1021/acsami.5b10459.[3] K. F. Mak, C. Lee, J. Hone, J. Shan, and T. F. Heinz, “Atomically Thin MoS 2 : A New Direct-Gap Semiconductor,” Phys. Rev. Lett., vol. 105, no. 13, p. 136805, Sep. 2010, doi: 10.1103/PhysRevLett.105.136805.[4] Y. Tsuboi et al., “Enhanced photovoltaic performances of graphene/Si solar cells by insertion of a MoS 2 thin film,” Nanoscale, vol. 7, no. 34, pp. 14476–14482, 2015, doi: 10.1039/C5NR03046C.[5] N. A. Abd Malek et al., “Ultra-thin MoS2 nanosheet for electron transport layer of perovskite solar cells,” Optical Materials, vol. 104, p. 109933, Jun. 2020, doi: 10.1016/j.optmat.2020.109933.[6] Y.-J. Huang, H.-C. Chen, H.-K. Lin, and K.-H. Wei, “Doping ZnO Electron Transport Layers with MoS 2 Nanosheets Enhances the Efficiency of Polymer Solar Cells,” ACS Appl. Mater. Interfaces, vol. 10, no. 23, pp. 20196–20204, Jun. 2018, doi: 10.1021/acsami.8b06413.[7] S. Abdul Hadi, G. Dushaq, and A. Nayfeh, “Effect of atomic layer deposited Al 2 O 3 :ZnO alloys on thin-film silicon photovoltaic devices,” Journal of Applied Physics, vol. 122, no. 24, p. 245103, Dec. 2017, doi: 10.1063/1.4990871.[8] T. Li and G. Galli, “Electronic Properties of MoS 2 Nanoparticles,” J. Phys. Chem. C, vol. 111, no. 44, pp. 16192–16196, Nov. 2007, doi: 10.1021/jp075424v.[9] Z. Lou et al., “High-performance MoS_2/Si heterojunction broadband photodetectors from deep ultraviolet to near infrared,” Opt. Lett., vol. 42, no. 17, p. 3335, Sep. 2017, doi: 10.1364/OL.42.003335.[10] A. P. Sunitha, P. Praveen, M. K. Jayaraj, and K. J. Saji, “Upconversion and downconversion photoluminescence and optical limiting in colloidal MoS2 nanostructures prepared by ultrasonication,” Optical Materials, vol. 85, pp. 61–70, Nov. 2018, doi: 10.1016/j.optmat.2018.08.038.[11] Y. Wu et al., “Monolithic integration of MoS 2 -based visible detectors and GaN-based UV detectors,” Photon. Res., vol. 7, no. 10, p. 1127, Oct. 2019, doi: 10.1364/PRJ.7.001127. Figure 1

Two-dimensional silver film for all-inorganic transparent photovoltaics

A transparent conductor with aluminum-doped zinc oxide (AZO)/Ag/Cu structure was developed and applied for extracting power from transparent photovoltaics. The Cu layer serves as seed layer for the two-dimensional growth of an Ag film. The AZO layer is used to enhance the optoelectrical properties of Cu/Ag. The AZO/Ag/Cu film exhibits a high visible transmittance of 83.1% and a sheet resistance of 18 Ω/□. Importantly, the proposed Cu/Ag/AZO transparent conductor enables the development of transparent and flexible NiO/ZnO-based photovoltaics with a power conversion efficiency of 1.14%. These results shows that the present system may be a promising platform for cost-effective and high-performance flexible optoelectronics.

Photothermoelectric AZO/SiO2/NiO Device

AbstractTransparent‐conductive‐oxide (TCO) materials and transparent devices combining photovoltage and thermoelectric effects are still scarce. Hence, a new transparent‐conductive‐oxide/insulating/transparent‐semiconductor‐oxide (TCO‐I‐TSO) structure combining such effects is developed. It is made of aluminum‐doped zinc oxide (AZO)/SiO2/NiO thin films sequentially deposited on glass substrates. AZO exhibits thermo and photovoltage in response to gradient temperature and absorption of UV photons, while NIR photons absorption in the NiO layer. Photovoltage appears in the plane between the AZO and NiO layer when the whole sample is irradiated with near infrared light, and it also depends on the thickness of the SiO2 layer. This photovoltage is continuously monitored on samples placed in a glass window facing south. Throughout the day, the photovoltage varies from 0 to 300 µV proportionally to the light intensity.

Excitation of Epsilon‐Near‐Zero Mode in Optical Fiber

AbstractExperimental excitation of a highly confined epsilon‐near‐zero (ENZ) mode in a side‐polished optical fiber coated with a deep subwavelength thick layer of aluminum‐doped zinc oxide (AZO) is reported. The uniform AZO layer on the fiber is fabricated by atomic layer deposition technique and optimized to exhibit close‐to‐zero permittivity at the near‐infrared wavelength. Highly polarization‐ and wavelength‐dependent transmission with strong resonance strength up to 25 dB is observed in a 30‐nm ENZ‐coated fiber that is 17 mm long. Different from the excitation of the ENZ mode in a planar conducting oxide thin film, the hybrid ENZ mode can be excited via direct phase matching between the fundamental mode of the fiber and the ENZ mode supported by the AZO thin film. The hybrid ENZ mode in the fiber exhibits a relatively long propagation/light–matter interaction length which is a few orders of magnitude longer than those on the planar ENZ substrates. It is further shown that the hybrid resonance in the ENZ fiber can be actively tuned through the refractive index of surrounding medium and the large ENZ's nonlinearity. These ENZ‐optical fibers serve as emerging in‐fiber optical devices, such as advanced in‐fiber ultrafast optical switches/modulators, mode‐locked fiber lasers, and in‐fiber optical gas/biomolecule sensors.

Front SiON/TCO Stacks Development for Double-Side Poly-Si/SiOX Passivated Contacts Solar Cells

This article reports on the use of a front-side SiON/transparent conductive oxide (TCO) bilayer in double-side poly-Si/SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">X</sub> -based passivated contacts solar cells. This approach presents the advantage of a low indium consumption either by reducing the indium-based TCO thickness or by enhancing its substitution with a zinc-based TCO, such as aluminum-doped zinc oxide (AZO). Thickness optimizations with optical simulations have been performed. An electrical study with a TCO thickness reduced to 20 nm on textured surfaces has shown excellent responses for SiON/TCO stacks, especially regarding the contact resistivity. Finally, the developed SiON/TCO bilayers were integrated in complete solar cells. Interestingly, the substitution of the standard 70-nm-thick ITO layer by a 20-nm-thick ITO film covered by SiON led to an efficiency gain of +0.2% abs. Regarding AZO, the replacement of the standard 70-nm-thick AZO layer by a 20-nm-thick AZO film covered by SiON resulted in a <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">J</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">SC</sub> gain of +0.7 mA/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . These gains in performances could be raised with further posttreatments. However, the current results already confirm the possibility to optimize thin-poly-Si-based passivated contacts solar cells toward In-free fabrication processes.

Early Stages of Aluminum-Doped Zinc Oxide Growth on Silicon Nanowires.

Aluminum-doped zinc oxide (AZO) is an electrically conductive and optically transparent material with many applications in optoelectronics and photovoltaics as well as in the new field of plasmonic metamaterials. Most of its applications contemplate the use of complex and nanosized materials as substrates onto which the AZO forms the coating layer. Its morphological characteristics, especially the conformality and crystallographic structure, are crucial because they affect its opto-electrical response. Nevertheless, it was difficult to find literature data on AZO layers deposited on non-planar structures. We studied the AZO growth on silicon-nanowires (SiNWs) to understand its morphological evolution when it is formed on quasi one-dimensional nanostructures. We deposited by sputtering different AZO thicknesses, leading from nanoclusters until complete incorporation of the SiNWs array was achieved. At the early stages, AZO formed crystalline nano-islands. These small clusters unexpectedly contained detectable Al, even in these preliminary phases, and showed a wurtzite crystallographic structure. At higher thickness, they coalesced by forming a conformal polycrystalline shell over the nanostructured substrate. As the deposition time increased, the AZO conformal deposition led to a polycrystalline matrix growing between the SiNWs, until the complete array incorporation and planarization. After the early stages, an interesting phenomenon took place leading to the formation of hook-curved SiNWs covered by AZO. These nanostructures are potentially very promising for optical, electro-optical and plasmonic applications.

Morphology, Electrical and Optical Properties of Cu Nanostructures Embedded in AZO: A Comparison between Dry and Wet Methods.

Herein, Cu nanostructures are obtained by solid-state dewetting of 9 nm copper layer (dry) or by ablating copper target, using a nanosecond pulsed laser at 1064 nm, in acetone and isopropyl alcohol (wet). The Cu nanostructures are embedded in aluminum-doped zinc oxide layer. Then, the electrical, optical, and morphological properties of the two kinds of systems, as a function of their synthesis parameters, are investigated. The aim is to compare the two fabrication methods and select the main conditions to achieve the best system for photovoltaic applications. The main differences, exhibited by the wet and dry processes, were in the shape and size of the Cu nanostructures. Dewetting in nitrogen produces faceted nanoparticles, with an average size below 150 nm, while laser ablation originates spherical and smaller nanoparticles, below 50 nm. Dry system underwent to thermal annealing, which improves the electrical properties, compared to the wet system, with a sheet resistance of 103 vs. 106 Ω/sq, respectively; finally, the dry system shows a maximum transmittance of 89.7% at 697 nm, compared to the wet system in acetone, 88.4% at 647 nm, as well as in isopropyl alcohol, 86.9% at 686 nm. Moreover, wet systems show higher transmittance in NUV.

Hydrogen Sensing Properties of an Aluminum-Doped Zinc Oxide Layer Decorated With Palladium Nanoparticles

Hydrogen Sensing Properties of an Aluminum-Doped Zinc Oxide Layer Decorated With Palladium Nanoparticles

Thermal Stability of the Copper and the AZO Layer on Textured Silicon

Transparent conductive oxide (TCO) film is the most widely used front electrode in silicon heterojunction (SHJ) solar cells. A copper metallization scheme can be applied to the SHJ process. The abundance of zinc in the earth’s crust makes aluminum-doped zinc oxide (AZO) an attractive low-cost substitute for indium-based TCOs. No work has focused on the properties of the copper and AZO layers on the textured silicon for solar cells. This work deposited an aluminum-doped zinc oxide layer and copper metal layer on textured (001) silicon by a sputtering to form Cu/AZO/Si stacks. The structures of Cu/AZO/Si are characterized by scanning electron microscope (SEM), scanning transmission electron microscope (STEM), and energy-dispersive X-ray spectrometer (EDS). The results show that the copper thin film detached from AZO in the valley of the textured silicon substrate at a temperature of 400 °C. Additionally, the gap between the copper and AZO layers increases as temperature increases, and the 65 nm thickness AZO layer was found to be preserved up to 800 °C.

A Study on Formation of Aluminum-Doped Zinc Oxide Films by Pulsed-Direct Current Sputtering for CIGS Solar Cells.

Considering the relationship between thin film thickness of transparent conductive oxide (TCO) materials and the reversed pulse time in pulsed-direct current (DC) sputtering, aluminum-doped zinc oxide (AZO) films were deposited on glass substrates at different reversed pulse times by changing oxygen/argon (O₂/Ar) gas ratios for window layers of large area CuIn1-xGaxSe₂ (CIGS) solar cells. As a result of the reduced sputtering time, the thickness of AZO film was decreased when the reversed pulsed time was increased. The higher resistance and resistivity of the AZO film was obtained at a higher reversed pulse time. From the structural investigations of AZO such as transmittance and X-ray diffraction (XRD), it was possible to observe the relationship between the crystallinity of AZO and transmittance. Even at the short reversed pulse time of 0.5 µs, it can be concluded that the accumulated charges on the AZO target are completely cleared and the AZO layers show the highest figure of merit (FOM) with low sheet resistance and high transmittance.

Preparation and property optimization of silver-embedded FTO transparent conductive thin films by laser etching and coating AZO layer

Preparation and property optimization of silver (Ag)-embedded fluorine-doped tin oxide (FTO) films were achieved based on laser etching, sputtering Ag layers, furnace annealing, sputtering aluminum-doped zinc oxide (AZO) layers and laser annealing. Specifically, a nanosecond pulsed laser (λ = 532 nm) was used to etch grooves on FTO films before sputtering 5-nm-thick Ag layers, with an aim for enabling the Ag nanoparticles from the furnace-annealed Ag layers to be intensively embedded in the grooves under the thermal-induced dewetting effect. The optimal laser fluence for laser etching and temperature for furnace annealing were found to be 0.4 J/cm2 and 300 °C, respectively. The as-obtained Ag-embedded FTO film exhibited significantly improved optical and electrical properties, being attributed mainly to the decreased coverage area of the Ag nanoparticles on the FTO film surface and the furnace annealing effect. The subsequently sputtered 10-nm-thick AZO layer suppressed the internal light reflection from the Ag nanoparticles, and laser annealing further facilitated grain growth in the film. Therefore, the resulting film had the best comprehensive property with the highest figure of merit of 20.94 × 10–3 Ω–1, which was much higher than that of the original FTO film (7.65 × 10–3 Ω–1). This work may provide a new combined processing method for high-performance transparent conductive films.

Ag Functionalization of Al-Doped ZnO Nanostructured Coatings on PLA Substrate for Antibacterial Applications

Developing smart, environmentally friendly, and effective antibacterial surfaces is fundamental to contrast the diffusion of human infections and diseases for applications in the biomedical and food packaging sectors. To this purpose, here we combine aluminum-doped zinc oxide (AZO) and Ag to grow nanostructured composite coatings on bioplastic polylactide (PLA) substrates. The AZO layers are grown by RF magnetron sputtering, and then functionalized with Ag in atomic form by RF magnetron sputtering and in form of nanoparticles by supersonic cluster beam deposition. We compare the morphology, wettability, and antimicrobial performance of the nanostructured coatings obtained by the two methods. The different growth modes in the two techniques used for Ag functionalization are found to produce some differences in the surface morphology, which, however, do not induce significant differences in the wettability and antimicrobial response of the coatings. The antibacterial activity is investigated against Escherichia coli and Staphylococcus aureus as representatives of Gram-negative and Gram-positive bacteria, respectively. A preferential antimicrobial action of Ag on the first species and of AZO on the second one is evidenced. Through their combination, we obtain a hybrid composite coating taking advantage of the synergistic dual action of the two materials deposited, with a total bacterial suppression within few minutes for the first species and few hours for the second one, thus representing a valuable solution as a wide-spectrum bactericidal device.

Preparation and Photoelectric Properties of Patterned Ag Nanoparticles on FTO/Glass Substrate by Laser Etching and Driving Layer Strategy

An effective method based on laser etching and driving layer strategy was proposed to prepare patterned Ag nanoparticles (Ag NPs) on fluorine-doped tin oxide (FTO)/glass substrate and thus to enhance the photoelectric properties. This method successively included depositing an aluminum-doped zinc oxide (AZO) driving layer, laser etching, depositing an Ag layer, furnace annealing and laser removal. Different AZO and Ag layer thicknesses were adopted, and the surface morphology, crystal structure and photoelectric properties were investigated. An Ag NPs/FTO/glass sample without an AZO driving layer was prepared for comparison. It was found that furnace annealing of the Ag layer combined with the AZO driving layer, rather than that without the AZO driving layer, was more conducive to generating patterned Ag NPs. Using a 20-nm-thick AZO layer and a 150-nm-thick Ag layer led to the formation of uniformly distributed Ag NPs being aligned along the laser-etched grooves to form a pattern. The as-obtained sample had the best comprehensive photoelectric property with an average transmittance of 79.95%, a sheet resistance of 7.11 Ω/sq and the highest figure of merit of 1.50 × 10−2 Ω−1, confirming the feasibility of the proposed method and providing enlightenment for related researches of transparent conductive oxide-based films.

Spectrophotometry of Layers on Plane Parallel Substrates

Integral expressions are obtained for the reflectance and transmittance spectra of a structure that is formed by two thin layers deposited on opposite faces of a plane-parallel substrate and that is obliquely illuminated with partially coherent light. As a result of an asymptotic analysis of the integrals, approximate analytical formulas are found for calculating the indicated spectra, which are convenient for use to solve inverse spectrophotometry problems. An aluminum doped zinc oxide layer deposited on a glass substrate is studied. The spectra of the refractive indices and absorbances of the layer and the substrate, as well as the layer thickness, are restored by processing the reflectance and transmittance spectra of the structure measured for s- and p-polarized waves at two angles of incidence of the light on the structure. The found parameters of the structure are used in computational experiments to estimate the applicability limits of the formulated approximations.

Improvement in structural, electrical, and optical properties of Al-doped ZnO nanolayers by sodium carbonate prepared via solgel method

The significant improvement in crystallinity, electrical, and optical properties of aluminum-doped zinc oxide (AZO) thin films was attained by Na doping. Both Al and Na contents were introduced into ZnO host via facile and cost-effective solgel method. Ultra-thin films of Na-doped AZO (NAZO), with thickness of about 40 nm, were deposited on glass substrates via spin-coating technique. The obtained results showed low sodium incorporation reduces the crystal strain which in turn leads to increase crystallite size from 31 nm for AZO to 49 nm for 2 at% Na-doped AZO layer. In addition, 2 at.% of Na doping, that was determined as an optimum level of doping concentration, decreased the macroscopic surface roughness (MRs) without notable changes in surface micro-cracks, leading to remarkable enhancement of the layer conductivity (about 54%). On the other hand, high concentration of sodium content (10 at%) increased the crystal strain and reduced the crystallinity order of AZO layer which resulted in high MRs and also high electrical sheet resistance. Optical dispersion curve and real and imaginary parts of dielectric constant were obtained using our precise method. More interestingly, 2 at% of Na doping led to an increase in transparency of AZO layer in the visible range, while its extinction coefficient (light power absorption) was enhanced which can be regarded as advantage for such thin films. Therefore, the optimum Na content can provide higher optical absorption even with higher transparency by reducing the light scattering and reflection. This finding provides a useful procedure to prepare transparent oxide semiconductor layers with noticeable light absorption, which is very interesting for various applications such as solar cells and anti-reflection coatings.

Atomic Layer-Deposited Al-Doped ZnO Thin Films for Display Applications

The integration of high uniformity, conformal and compact transparent conductive layers into next generation indium tin oxide (ITO)-free optoelectronics, including wearable and bendable structures, is a huge challenge. In this study, we demonstrate the transparent and conductive functionality of aluminum-doped zinc oxide (AZO) thin films deposited on glass as well as on polyethylene terephthalate (PET) flexible substrates by using an atomic layer deposition (ALD) technique. AZO thin films possess high optical transmittance at visible and near-infrared spectral range and electrical properties competitive to commercial ITO layers. AZO layers deposited on flexible PET substrates demonstrate stable sheet resistance over 1000 bending cycles. Based on the performed optical and electrical characterizations, several applications of ALD AZO as transparent conductive layers are shown—AZO/glass-supported liquid crystal (LC) display and AZO/PET-based flexible polymer-dispersed liquid crystal (PDLC) devices.

Effects of nitrogen/oxygen on the electrical and optical properties and microstructure of triple layer AZO/Ag/AZO thin films

Aluminum-doped zinc oxide (AZO)/Ag/aluminum-doped zinc oxide (AAA) specimens are prepared by varying O2 and N2 flow rates during the AZO deposition to investigate the gas effects on surface morphology, microstructure, conductivity type and optical and electrical properties. The AZO specimens are found to have decreases in grain size and RMS surface roughness (SRq), and an increase in compressive residual stress when the N2 flow rate increases higher than 2.5 sccm. The addition of O2 can contribute a similar tendency to grain size, SRq and residual stress; the grain size and SRq are always comparatively smaller, while the residual stress is higher than that prepared with N2. The grain size and SRq are obtained to be proportional to the AZO thickness, whereas they are inversely proportional to the compressive residual stress of AZO. Specimen D prepared with (N2: 0, O2: 2.5) sccm and having 60-nm AZO thickness possesses the strongest anti-reflection effect of the AAA structure, and therefore impedes the reflection from the Ag interlayer significantly. P-type conductivity is achieved by introducing the N2 into the AZO layers and (N2: 15, O2: 0) sccm is used to achieved the highest carrier concentration (CC) and mobility (Mb), and thus the lowest resistivity (R) of all specimens in this study. Increasing the O2 flow rate leads to decreases in Mb and CC, but can obtain the highest average transmittance ( T ¯ ) as (N2: 0, O2: 2.5) sccm is applied. The O2 flow rate becomes the dominant factor for the electrical and optical properties and microstructure as AZO films are deposited in the N2 and O2 mixed atmosphere. (N2: 15, O2: 0) sccm is used to achieve the highest CC and the lowest R of the oxide/metal/oxide specimens reported in the literatures.

Aluminum doped zinc oxide (AZO)-based pressure sensor

The feasibility of using aluminum-doped zinc oxide (AZO) as a piezoresistive pressure sensor material is reported. AZO has attracted a great deal of attention in many applications because of its nontoxicity, abundancy and lower cost than other materials such as indium tin oxide (ITO). The AZO films were deposited on polyethylene (PE) substrates by a radio-frequency (rf) magnetron sputtering method and they were used as the diaphragms of the pressure sensors. The piezoresistive sensor was tested for different pressures in vacuum and gage pressure conditions. The response characteristics indicated that resistance increased with the bending of the AZO layer in both compressive and tensile operation modes. The sensor characteristics exhibited that the AZO piezoresistive sensor can be used to measure ambient pressure quantitatively. This investigation indicated that AZO can be used as an alternative material for the fabrication of pressure sensors.

Спектроскопия слоев на плоскопараллельных подложках

Integral expressions for the reflectance and transmittance spectra of the structure consisted of two thin layers deposited on opposite faces of a plane-parallel substrate at oblique illumination of the structure with partially coherent light are obtained. As a result of the asymptotic analysis of the integrals, approximate analytical formulae are established for calculating the indicated spectra, convenient for use in solving inverse spectrophotometry problems. An aluminum doped zinc oxide layer deposited on a glass substrate is studied. The spectra of the refractive index and absorption coefficient of the layer and the substrate, as well as the thickness of the layer, are determined by processing the reflectance and transmission spectra of the structure, measured for s- and p- polarized waves at two angles of light incidence. The found parameters are used in computational experiments to estimate the applicability limits of the formulated approximations.