Al-doped ZnO Thin Films Research Articles

Study the characterization of ZnO and AZO films prepared by spray pyrolysis and the effect of annealing temperature

Spray-pyrolysis was used to successfully create ZnO and AZO (Al-doped ZnO) thin films on glass substrates at various annealing temperatures. Structure, morphology, and optical characteristics were investigated in relation to doping and annealing temperature using analytical techniques such as FTIR, UV–Vis spectroscopy, XRD, and FE-SEM. The films' singular-phase polycrystalline hexagonal Würtzite structure was revealed by XRD data, and the crystallographic plane for both AZO and ZnO was (0 0 2). Crystallite sizes are increased by raising the annealing temperature and adding Al-doping, which enhances surface morphology. where the diameters of the AZO crystallites expanded from 23.3 to 33.3 nm, whereas the ZnO crystallites grew from 27.8 to 28.5 nm. Scanning electron microscopy's morphology reveals that the surface particles' tiny, round shapes have changed to spherical clusters that resemble cauliflowers with increasing annealing temperatures. Notably, the ZnO film has a high transmittance, whereas the AZO film has a relatively low transmittance. Furthermore, at an annealing temperature of 400 °C, all films show notable absorbance, with the highest absorption seen at 400 and 413 nm for ZnO and AZO, respectively. The bandgap values at various annealing temperatures vary from 3.22 to 3.23 eV and 3.08–3.12 eV for ZnO and AZO, respectively. As the annealing temperature rose, the phenomena showed a drop in value.

Enhancing the efficiency of the organic-inorganic hybrid perovskite cells using Al-doped ZnO as an Electron Transport Layer and CNTs as a Hole Transport Layer: An experimental and numerical study

Perovskite solar cells (PSCs) have become the subject of much discussion in the photovoltaic field due to their excellent performance over the past few years. This study presents the production, characterization, and simulation of Al-doped ZnO (AZO) as an electron transport layer (ETL) at a concentration of 1% in organic-inorganic hybrid perovskite solar cells (PSC). We experimentally elaborate the AZO thin films using the sol-gel dip-coating method. We further examined the resulting film for structural, morphological, and optical properties for use in solar cells (SCs), using X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), and UV–visible spectroscopy. Furthermore, this work presents an optimization process led by simulation that generates high performance using CNTs, CH3NH3PbI3, and AZO as a hole transport layer (HTL), absorber layer, and ETL respectively in solar cells using SCAPS 1D software. We have carefully examined the impact of several parameters, including the layer thicknesses, temperature, defect density of the absorber layer, defect density at interfaces between AZO and perovskite and perovskite and CNTs, and series and shunt resistances (Rs and Rsh). An optimized PSC of ITO/AZO/MAPbI3/CNTs/Au is designed here with an efficiency of 25.62%, open-circuit voltage (Voc) of 1.3955 V, fill factor (FF) of 72.32%, and current density (Jsc) of 25.382 mA/cm2. Our findings provide a remarkable efficiency using the proposed model; nevertheless, as researchers, we still need to simulate and conduct experiments to increase the cell's efficiency to potentially use it in solar cells(SCs).

Crystal Al-Doped ZnO Thin-Film Preparation by Sputtering Deposition using a Mixed-Powder Target

Al-doped ZnO films were prepared by sputtering deposition using mixtures of Al2O3 and ZnO powder targets. The film quality depended on the conditions of the target powder. The deposition rate, crystallinity, and transparency of films prepared with new, pressed powder targets were higher than those prepared with used, nonpressed powder targets. In addition, we found that pressurizing the new-powder target and increasing the substrate temperature resulted in thin films with high transparency and electrical conductivity

Improving Surface Structures of Al-Doped Zinc Oxide Thin Films to Apply in CO Gas-Sensing Property by Designing Processes Through RF Magnetron Sputtering

Improving Surface Structures of Al-Doped Zinc Oxide Thin Films to Apply in CO Gas-Sensing Property by Designing Processes Through RF Magnetron Sputtering

Optical and electrical properties of Al-doped ZnO thin films deposited by sol-gel method

The multilayer (10 layers) Al doped ZnO (AZO) thin films were deposited on glass substrate by sol-gel & dipping method. X-Ray diffraction measurements showed that the AZO films were polycrystalline with a hexagonal wurtzite structure. The morphological properties of the films were analyzed by atomic force microscopy showing continuous and homogeneous film, completely covering the substrates. The thickness, optical constants, optical band gap (Eg) and transmittance (T) of AZO films were assessed by spectroscopic ellipsometry on UV-vis-NIR spectral range. The AZO film has high transmittance above 80% in the visible region and the optical band-gap energy around 3.7 eV. The electrical characteristics regarding conductivity, mobility and carrier concentrations, were measured by Hall Effect measurements (van der Pauw method). The bulk carrier concentration of the AZO film with 10 layers was found to be 1.16x1019 cm-3. The vibrational bands were obtained by Raman analysis. Defects due to oxygen vacancies in the prepared AZO films were evidenced by photoluminescence spectroscopy (PL). The optical and electrical properties of the AZO thin films proved the possibility to be used in optoelectronic applications.

Al-doped ZnO Thin Films via Sputtering: Influence of Structural Defects on Ozone Gas Sensitivity

Al-doped ZnO Thin Films via Sputtering: Influence of Structural Defects on Ozone Gas Sensitivity

Electrostatic Spray Deposition of Al-Doped ZnO Thin Films for Acetone Gas Detection

In this study, pure ZnO and Al-doped ZnO(AZO) thin films were coated onto a SiO2 wafer using the electrostatic spray deposition (ESD) process for acetone gas detection under laboratory conditions. Voltage levels were varied to determine the optimal conditions for producing thin films with the highest uniformity. The results indicate that the optimal coating voltage for achieving the highest uniformity of the coated films is 2.9 kV for ZnO and 2.6 kV for AZO. The thin films were produced under these optimal ESD conditions by adjusting the coating time, and gas sensors were fabricated by printing electrodes using a reverse offset process on top of the thin films. Analysis of the sensing response revealed that the AZO-coated gas sensor with a 200 s deposition exhibited the best acetone-sensing ability at 300 °C, with a maximum response of 13.41 at 10 ppm. Furthermore, the fabricated gas sensors effectively detected acetone gas even at a low concentration of 2 ppm, demonstrating high selectivity in comparison to other gases.

SYNTHESIS AND CHARACTERIZATION OF Al-DOPED ZnO THIN FILMS AS ANTI-REFLECTION COATINGS FOR SOLAR CELL APPLICATIONS

In this work, we have synthesized ZnO:Al thin films by pulsed laser deposition technique and investigated their microstructural and optical properties. The XRD study confirmed a polycrystalline structure of wurtzite ZnO in all films. Further, Al doping has improved the crystallinity and decreased the crystal size and volume of the unit cell. The surface morphology was homogeneous with nanoscopic crystals clustered to form granular nanoparticles. The optical properties significantly improved by increasing the Al doping concentration. The produced thin films are excellent candidates for use as an anti-reflection layer in solar cells due to their outstanding properties.

Multifunctional Al-doped ZnO thin films for vertically aligned liquid crystal devices

The integration of ITO-free transparent conductive layers remains a big challenge for development of next generation technologies. Here, we demonstrate the feasibility of transparent and conductive Aluminum-doped Zinc Oxide (AZO) thin films to operate simultaneously as electrode and alignment layer in Liquid Crystal (LC) device configuration. Controlling the growth process of AZO thin films by Atomic Layer Deposition (ALD) technique results of predominantly (100) crystallographic oriented AZO with very high transparency and excellent conductivity. The exceptionally low surface free energy of (100) oriented AZO, along with the topological modification following the mechanical rubbing treatment were used to elucidate the mechanism of LC molecules alignment on the surface of AZO film. The uniform vertical orientation of the nematic LC director was confirmed by polarized optical microscopy and pretilt angle measurements. The competitive electro-optical performance in terms of phase modulation, threshold and saturation voltages and contrast ratio of the assembled LC device reveals the great potential of AZO thin films as transparent electrode and alignment layer for future LC display applications with versatile functionality.

Engineering the visible light absorption of one-dimensional photonic crystals based on multilayers of Al-doped ZnO (AZO) thin films

Engineering the visible light absorption of one-dimensional photonic crystals based on multilayers of Al-doped ZnO (AZO) thin films

Toward Industrial Production of a High-Performance Self-Powered Ultraviolet Photodetector Using Nanoporous Al-Doped ZnO Thin Films.

Al-doped ZnO (AZO) thin films are effective n-type semiconductors for ultraviolet (UV) detection because of their low cost, high electron mobility, and high sensitivity to UV light, especially in the UVA spectrum. However, a reasonable compromise between performance (such as sensitivity, detectivity, and response time) and fabrication ease remains an obstacle to the practicability of AZO-based UV photodetectors. To address this issue, we propose an efficient strategy to achieve a large AZO photoactive area for outstanding performance, along with a facile sol-gel method. Consequently, the device exhibits a superb on/off ratio of >104, a high detectivity of 1.85 × 1012 Jones, and a fast response speed under 365 nm UVA illumination without external energy consumption. Hence, this study suggests a self-powered and high-performance nanoporous AZO-based UVA detector with an environmentally friendly scalable process that satisfies industrial production requirements for numerous practical UV-detection applications.

Enhanced Acetone Gas Sensing Properties of Al-Doped ZnO Thin Films Developed by Sol-Gel Dip Coating Method

The acetone sensing capabilities of pure and Al-doped ZnO thin films developed by the sol-gel dip coating technique were examined inthis study. An investigation was conducted to examine the impact of Al doping concentration on the structural, morphological and sensing characteristics of the films. The results showed that acetone gas detection in ZnO thin films might be enhanced by doping with Al. In particular, when exposed to 10 ppm of acetone at room temperature, the response of 3 at% Al-doped ZnO thin film was the highest, achieving 53% and showed a fast response time of 6 s and a recovery time of 32 s. The researchers conducted additional investigations into the selectivity of acetone in the film when exposed to various interfering gases. The results revealed that acetone exhibited a favourable level of selectivity. The results presented herein demonstrate the effectiveness of sol-gel dip-coated thin films of Al-doped ZnO in the context of acetone gas sensing applications.

High figure-of-merit in Al-doped ZnO thin films grown by ALD through the Al content adjustment

The development of transparent conductive materials is of great interest for a wide variety of semiconducting devices in the fields of optoelectronics and photovoltaics. Here, we optimize the growth and properties of aluminum-doped ZnO (AZO) thin films as an eco-friendly transparent electrode by using atomic layer deposition (ALD) with diethylzinc (DEZn), water vapor and trimethylaluminium (TMA) as zinc, oxygen, and aluminum chemical precursors, respectively. The cycle ratio of DEZn to TMA using ALD is adjusted to control the Al atomic concentration over a broad range of 0.3 - 6.7% while optimizing the structural, optical, and electrical properties of AZO thin films. By incorporating a sufficient amount of Al dopants around 1.1%, we obtain a high quality AZO thin film exhibiting a low electrical resistivity of 6.3 × 10−4 Ω·cm. This AZO thin film grown on quartz substrate also demonstrates an average optical transmittance in the visible range above 85% as well as a high figure-of-merit of 6.4 × 10−3 Ω−1, while maintaining its highly c-axis oriented structure. The present optical and electrical properties result in the fabrication of AZO thin films by ALD with a high figure-of-merit that is highly suitable for many semiconducting devices.

Sol–gel deposition of Al-doped ZnO thin films: effect of additional zinc supply

Sol–gel deposition of Al-doped ZnO thin films: effect of additional zinc supply

GROWTH AND PROPERTIES OF SPIN-COATED TRANSPARENT SN AND AL-DOPED ZNO THIN FILMS

In this work, Zinc Oxide (ZnO) thin films doped and undoped with Sn and Al were grown on ITO substrates by the sol–gel spin coating technique, where the Sn/Zn and Al/Zn atomic ratios were, respectively, 5% and 7% in the solution. SZO and AZO structures were examined using XRD, AFM, SEM, UV–vis spectroscopy, and photoluminescence (PL) to investigate the morphology, structural, and optical characteristics. According to XRD analysis, all of the produced films have a hexagonal wurtzite structure with a polycrystalline nature oriented along the (1 0 0) direction. The crystallite size was calculated using the well-known Scherrer’s formula and found to be in the range of 23–40 nm. Scanning Electron Microscopy (SEM) results revealed that Sn and Al low doping had an impact on the morphological surface of the films. The measurements from the UV-Visible Spectrophotometer (U–Vis) showed that undoped ZnO film has a high optical transparency in the visible region (over [Formula: see text]%), and then the optical band gap of thin films was calculated. PL is observed for ZnO thin films doped and undoped with Sn and Al.

Comprehensive characterization of Al-doped ZnO thin films deposited in confocal radio frequency magnetron co-sputtering

Al-doped ZnO thin films with varying Aluminium (Al) content were deposited by radio frequency magnetron co-sputtering of two ZnO and Al targets in confocal configuration. A comprehensive study of the effect of Al content variation on the structural, optical and electrical properties were studied for as-deposited films and after an annealing step under controlled argon atmosphere. Chemical composition analyses, performed by both X-ray photoelectron spectroscopy and energy dispersive X-ray spectrometry, show an Al content variation in the deposited films in the 0-14 at.% range by varying the Al target power from 0 to 30 W, while the Zn target power was kept constant at 200 W. All deposited films exhibit a wurtzite crystalline structure and a decreasing crystalline quality for Al content above 5 at.% as shown by grazing incidence X-ray diffraction patterns. Atomic Force Microscopy analysis revealed films with homogeneous and dense surface morphology with roughness in the one nm range. Carrier concentration, resistivity and photoluminescence vary significantly with Al content in the ZnO films and appear optimized for an Al content window ranging from 1.5 to 5.5 at. %. Both optical and electrical properties are improved by a post-annealing at 300°C under argon. A high figure of merit of 43.6 × 10-4 sq.Ω-1 was obtained for the ZnO film with Al content of 3.6 at.% after annealing at 300°C. Optimized properties are obtained for a higher Al content than the standard value of 2 at. % widely used in published works.

Enabling high-quality transparent conductive oxide on 3D printed ZrO2 architectures through atomic layer deposition

The conformal atomic layer deposition of a transparent conductive oxide composed of Al-doped ZnO (AZO) over three-dimensional (3D) shaped ZrO2 microarchitectures produced using two-photon lithography (TPL) is reported here for the first time. The effect of ZrO2 morphology, surface roughness, and crystallographic phase (tetragonal and monoclinic) on the quality and properties of the deposited ZnO and AZO thin films is investigated. No discontinuities, domains, or areas differing from the desired chemical composition have been found in films grown over the 3D structures. Three different Al dopant concentrations (4.0 %, 4–5 %, and 5.0 % Al doping cycles) are examined and compared to undoped ZnO. AZO and ZnO optical and electrical properties are studied using cathodoluminescence (CL) and Hall effect measurements. The CL study confirms that the observed emissions from the ZnO and AZO films are associated with the near band emission of ZnO and defects, i.e., zinc and oxygen vacancies and interstitial oxygen. The AZO films exhibit n-type semiconductor behavior, and a minimum resistivity of 1.2 × 10-3 Ω cm is achieved. From a broad perspective, AZO deposition on 3D microarchitectures opens a new route towards dimensionally refined optoelectronic devices in which the ZrO2/AZO can serve as an enabling role for the production of electrodes.

Enhanced ultraviolet photodetector based on Al-doped ZnO thin films prepared by spray pyrolysis method

Enhanced ultraviolet photodetector based on Al-doped ZnO thin films prepared by spray pyrolysis method

Effect of Al Incorporation on the Structural and Optical Properties of Sol-Gel AZO Thin Films.

ZnO and Al-doped ZnO (AZO) thin films were prepared using the sol-gel method and deposited on a Silicon (Si(100)) substrate using the dipping technique. The structure, morphology, thickness, optical constants in the spectral range 300-1700 nm, bandgap (Eg) and photoluminescence (PL) properties of the films were analyzed using X-ray diffractometry (XRD), X-ray fluorescence (XRF), atomic force microscopy (AFM), scanning electron microscopy (SEM), spectroscopic ellipsometry (SE), Raman analysis and PL spectroscopy. The results of the structure and morphology analyses showed that the thin films are polycrystalline with a hexagonal wurtzite structure, as well as continuous and homogeneous. The PL background and broader peaks observable in the Raman spectra of the AZO film and the slight increase in the optical band gap of the AZO thin film, compared to undoped ZnO, highlight the effect of defects introduced into the ZnO lattice and an increase in the charge carrier density in the AZO film. The PL emission spectra of the AZO thin film showed a strong UV line corresponding to near-band-edge ZnO emission along with weak green and red emission bands due to deep-level defects, attributed to the oxygen-occupied zinc vacancies (OZn lattice defects).

Effect of aluminum doping on the structural, optical and electrical properties of ZnO thin films processed under thermal shock conditions

The structural, morphological, optical, and electrical properties of Al-doped ZnO thin films annealed under thermal shock conditions were studied. The films were prepared using the sol–gel method and deposited on glass substrates by dip-coating technique. The effects of varying the concentration of aluminum (Al) were analyzed using X-ray Diffraction (XRD), scanning electron microscope (SEM), UV–Vis, and the 4-point probe method. The XRD data demonstrated a degradation in the crystalline structure of the films and the emergence of other preferred directions (100) and (101), which supported the creation of a hexagonal wurtzite structure. The SEM images supported the findings of the XRD analysis. The best electrical and optical performance was obtained for an Al concentration of 1 at%, where the resistivity value was 0.191 Ω.cm and the band gap was 3.26 eV, with a high transmittance greater than 90%.The findings of this study render the developed thin-film architecture a viable candidate for high-performance optoelectronic applications.