Transition Metal Doped Zinc Oxide Research Articles

Potential for multi-application advancements from doping zirconium (Zr) for improved optical, electrical, and resistive memory properties of zinc oxide (ZnO) thin films

Transition metal-doped Zinc oxide (ZnO) thin films with an optimal wide band gap and semiconducting nature find numerous applications in optoelectronic devices, gas sensors, spintronic devices, and electronics. In this study, Zirconium (Zr) doped ZnO thin films were deposited on ITO (Indium Tin oxide) coated glass substrate using RF-magnetron sputtering. Optical and electrical properties were examined for their potential use in resistive random-access memory (RRAM) applications. X-ray Diffraction (XRD), UV–vis spectroscopy, x-ray photoelectron spectroscopy (XPS), Atomic force microscopy (AFM) and Scanning electron microscopy (SEM) were used to investigate structural, optical, and compositional properties and roughness respectively. The results demonstrate that the films possess crystalline properties. Additionally, an augmentation in Zr concentration correlates with an elevation in the optical band gap, ascending from 3.226 eV to 3.26 eV, accompanied by an increase in Urbach energy from 0.0826 eV to 0.1234 eV. The film with the highest Zr content among all the films demonstrated the best electrical performance for resistive memory applications. Incorporating Zr as a dopant shows enhancement in the electrical performance and such ZnO films with optimum concertation of Zr can potentially be used in RRAM. ZnO being a versatile host material, its doping with Zr may extend its applications in catalysis, gas sensing, energy storage, and biomedical engineering. ZnO thin films employ zirconium (Zr) as a dopant, which is a novel way to improve the material’s characteristics. Although ZnO has been thoroughly researched, adding Zr presents a novel technique to enhance optical, electrical, and resistive memory characteristics all at once that has not been fully investigated.

Tuning the structural, optical and magnetic properties of transition metal doped zinc oxide nanoparticles

Tuning the structural, optical and magnetic properties of transition metal doped zinc oxide nanoparticles

Aqueous solution processed transition-metal-doped ZnO as electron injection layers for efficient inverted organic light emitting diodes

Zinc oxide (ZnO) has attracted lots of attention to be used as interfacial materials in organic optoelectronic devices owing to its attractive properties. In this work, a series of transition-metal-doped ZnO thin films were prepared by using a facile aqueous solution process, thereafter these films were employed as electron injection layers (EILs) combined with the tris-(8-hydroxyquinoline) aluminum (Alq3) emitting layer to construct the inverted organic light-emitting diodes (IOLEDs). The transition-metal-doped ZnO EIL-based IOLEDs demonstrate markedly improved device performance compared to the reference neat ZnO EIL-based IOLED. However, different transition-metal ions have much different doping effect on the device performance. CoCl2 doped ZnO EIL based IOLED device possesss an optimal current efficiency of 5.52 cd A−1, which is increased about 40% compared to the device with the neat ZnO as EIL. The enhancement might be attributed to the increased electron mobility and favorable interfacial energy level alignment of the transition-metal doped ZnO EIL for more efficient electron injection. Our findings may provide a promising strategy to improve the electron injection properties of ZnO film in the OLED devices.

Investigation of Photoluminescence and Optoelectronics Properties of Transition Metal-Doped ZnO Thin Films.

Thin films of zinc oxide (ZnO) doped with transition metals have recently gained significant attention due to their potential applications in a wide range of optoelectronic devices. This study focuses on ZnO thin films doped with the transition metals Co, Fe, and Zr, exploring various aspects of their structural, morphological, optical, electrical, and photoluminescence properties. The thin films were produced using RF and DC co-sputtering techniques. The X-ray diffraction (XRD) analysis revealed that all the doped ZnO thin films exhibited a stable wurtzite crystal structure, showcasing a higher structural stability compared to the undoped ZnO, while the atomic force microscopy (AFM) imaging highlighted a distinctive granular arrangement. Energy-dispersive X-ray spectroscopy was employed to confirm the presence of transition metals in the thin films, and Fourier-transform infrared spectroscopy (FTIR) was utilized to investigate the presence of chemical bonding. The optical characterizations indicated that doping induced changes in the optical properties of the thin films. Specifically, the doped ZnO thin film's bandgap experienced a significant reduction, decreasing from 3.34 to 3.30 eV. The photoluminescence (PL) analysis revealed distinguishable emission peaks within the optical spectrum, attributed to electronic transitions occurring between different bands or between a band and an impurity. Furthermore, the introduction of these transition metals resulted in decreased resistivity and increased conductivity, indicating their positive influence on the electrical conductivity of the thin films. This suggests potential applications in solar cells and light-emitting devices.

Determination of bandgap of period 3, 4, and 5 transition metal dopants on zinc oxide using an artificial neural network based approach

Artificial intelligence (AI) and machine learning (ML) have rapidly emerged as valuable tools for chemical research, offering new ways to analyze and understand complex chemical systems. This research article investigates the use of adaptive neuro-fuzzy inference system (ANFIS) and multi-layer perceptron (MLP) models to predict the bandgap of transition metal doped zinc oxide (ZnO). The opto-electronic properties of transition metal doped ZnO complexes are of significant interest because of their applications is optoelectronic systems. The MLP and ANFIS models were trained using a dataset of experimentally measured bandgap values and the corresponding structural parameters of the doped ZnO systems. The performance of the models was evaluated using statistical metrics i.e., RMSE, R, and MAE. The results showed that both MLP and ANFIS models were capable of accurately predicting the bandgap of transition metal doped ZnO. However, the ANFIS model demonstrated superior performance with higher accuracy and better generalization ability. The study provides a useful approach for predicting the bandgap of transition metal doped ZnO using machine learning techniques and may contribute to the development of advanced optoelectronic devices.

Optical, Photocurrent, Electrical, Structural, and Morphological Properties of Magnetron Sputtered Pure and Iron-Doped Zinc Oxide Thin Films

Due to its excellent physical and chemical properties, transition metal-doped zinc oxide has potential applications in different fields. In this research paper, pure and iron-doped ZnO films were deposited by thermal oxidation of sputtered metallic zinc and iron. The effect of iron (Fe) doping on the optical, morphology, structural, electrical, and photocurrent properties of zinc oxide films was examined. The X-ray diffraction analysis shows a wurtzite structure with preferential orientation for all films, where the high texture coefficient values (above 3) corresponded to the (002) plane. Fe doping reduced the crystallite size from 12.3 to 8.7 nm and lattice constants c and a values from 5.19 to 5.155 Å and from 3.236 to 3.203 Å respectively. The different calculated structure parameters, confirm the incorporation of Fe (Fe3+) in the ZnO lattice. The surface morphology of thin films measured using atomic force microscopy revealed that the Fe doping could markedly decrease the grains size from 248 to 54 nm and the Root–Mean–Square roughness of films from 5.27 to 4.22 nm. For all films, the transmittance analysis shows a transmittance above 90% in the visible region and with an increase in the Fe concentration, the transmittance, and the absorption in the ultraviolet region were increased. The gap energy of ZnO strongly increased from 3.26 to 3.51 eV with doping. The effect of Fe doping on different optical parameters was discussed in detail. The photoluminescence analysis of pure and doped ZnO exhibits one ultraviolet emission (384 nm) and green emission. Compared to pure ZnO, the ultraviolet peak intensity decreased as Fe content increased. The electrical resistivity was decreased and the photocurrent properties of ZnO were enhanced by Fe doping. In this report, Fe-doped ZnO films exhibited remarkable properties. Therefore such films can be usefully used in different device applications.

Experimental and DFT study of structural and optical properties of Ni-doped ZnO nanofiber thin films for optoelectronic applications

As an important metal oxide semiconductor, transition metal-doped zinc oxide (ZnO) has attracted great interest for various applications in optoelectronic, spintronic photovoltaic and photodetectors due to its significant chemical and physical properties. In this research study, pure and nickel (Ni)-doped ZnO nanostructured films were synthesized via the sol-gel method using the spin coating technique on glass substrates. The structural results revealed that all samples exhibited a polycrystalline wurtzite structure and a (002) plane preferred orientation. The crystallite size was reduced by Ni doping. The morphology micrographs indicate that the surface of thin films shows nanofiber structures. An optical study revealed the high transparency of the films. The photoluminescence (PL) showed one ultraviolet (UV) emission at 387 nm and different defect emissions for all films. The absorption, band gap and PL emissions intensities were influenced by Ni doping. Ni-doped ZnO nanostructured thin films revealed high UV sensitivity and photoresponse. Therefore, these thin films are a promising material for a UV photodetector. The dielectric function, absorption coefficient and energy band gap were also calculated and discussed by density functional theory (DFT), using the Ultra Soft Pseudo Potential (US-PP) approach implemented in the CASTEP code.

Effects of doping zinc oxide nanoparticles with transition metals (Ag, Cu, Mn) on photocatalytic degradation of Direct Blue 15 dye under UV and visible light irradiation.

Azo dyes represent the most commonly used group of dyes in the textile industry. These organic dyes are mainly resistant to biodegradation and may exhibit toxic and carcinogenic properties. The purpose of this study was to investigate the effects of doping zinc oxide (ZnO) nanoparticles (NPs) with transition metals (silver, manganese, and copper) on the photocatalytic efficiency of ZnO NPs in the removal of Direct Blue 15 dye from aqueous environments under ultraviolet (UV) radiation and visible light irradiation. One or two metals were used for doping the NPs. In total, seven types of undoped and transition metal-doped NPs were synthesized using the thermal solvent method with ZnO precursors and transition metal salts. The characteristics of the synthesized NPs were determined based on the scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, dynamic light scattering (DLS), atomic force microscopy (AFM), and zeta potential measurements. The produced ZnO NPs did not exhibit any particular photocatalytic activities under UV radiation and visible light irradiation. The highest removal efficiency under UV radiation was about 74% in the presence of silver-doped ZnO NPs, while the maximum efficiency under visible light was 70% in the presence of copper-doped ZnO NPs. The lowest removal efficiency was related to pure ZnO, which was 18.4% and 14.6% under UV and visible light irradiation, respectively. Although the efficiency of dye removal under visible light was not high compared to UV radiation, this efficiency was noteworthy in terms of both practical and economic aspects since it was achieved without the presence of ultraviolet radiation. The synthesis of transition metal-doped ZnO nanophotocatalysts (with one or two metals) under UV radiation or visible light irradiation could be used as an efficient and promising technology for the photocatalytic removal of Direct Blue 15 dye from aqueous environments.

Synthesis, characterization and photoresponse study of undoped and transition metal (Co, Ni, Mn) doped ZnO thin films

The synthesis, characterization and photoresponse studies of undoped and transition metal doped zinc oxide thin films are carried out in this work, in prospect of visible light photo detection and sensor applications. The undoped and transition metal ions such as, Co, Ni and Mn doped ZnO films in this study were synthesized by chemical solution deposition, involving spin-coating. We have characterized the deposited films using X-ray diffraction, scanning electron microscopy, photoluminescence and UV–vis spectroscopy studies. The devices of the films for photoresponse study were fabricated by top Ag contacts on the film surface in metal–semiconductor–metal configuration. The current–voltage characteristics and switching measurements of these devices were studied under the illumination of an incandescent lamp. We found a high ON/OFF ratio of 8 and highest photocurrent density of 0.7 mA/cm2 for Ni doped ZnO film.

FIRST PRINCIPLES STUDY OF EFFECT OF 3d TRANSITION METAL-DOPED ZINC OXIDE ON GAS SENSITIVITY

Two series models were developed in order to investigate the gas sensitivity of 3d transition metal-doped zinc oxide (ZnO) materials. Software based on a discrete variation method (DVM) within the framework of density functional theory was used to calculate the electronic structures of the models. It was possible to determine gas sensitivity using the calculated results, from which a relationship between electronic properties and gas sensitivity was formed. The results showed that doping the transition metals greatly affected the gas sensitivity of ZnO -based materials. The main effect was attributed to the change in carrier concentration. On the contrary, the doping of transition metals had a negligible effect on the mobility of ZnO -based materials. Titanium or iron doped- ZnO is thus expected to have the best gas sensitivity of all of the 3d transition metal-doped ZnO materials.

Magnetic and optical properties of single crystals of transition metal doped ZnO

AbstractConsiderable effort has been devoted to the study of transition metal doped zinc oxide following various theoretical predictions of room temperature ferromagnetism in these materials. Near equilibrium growth techniques may be suitable for the production of dilute transition metal doped ZnO because the transition metal solubility in ZnO can be relatively high. This work reports on the optical, structural, and magnetic properties of single crystals of Co‐ and Mn‐doped ZnO grown by a modified melt‐growth technique. X‐ray diffraction reveals that the as grown crystals are pure single crystals with no second phases. Mn doping up to 5% results in an increase in c‐axis lattice parameter (5.207 Å to 5.211 Å), and X‐ray linewidths (78 arcsec to 252 arcsec) at doping levels of 5% Mn. Optical transmission shows distinct absorption spectra related to the color of the Zn1–x TMx O sample resulting from interatomic transitions within the divalent transition metal ion. Electron paramagnetic resonance confirms the divalent nature of the substitutional transition metal ions. Raman spectroscopy shows the predominantly the E2 (high) peak at 407 cm–1, but with increasing doping shows additional disorder‐related modes. The magnetic behavior reveals a paramagnetic behavior at all temperatures for both Mn‐ and Co‐doped ZnO up to transition metal doping levels of 5% and 3% respectively. The dominant exchange mechanism in the Mn‐ and Co‐doped ZnO crystals is found to be antiferromagnetic superexchange. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

First-principles calculations on magnetism of transition metal doped zinc oxide

Abstract We calculated the electronic structure and magnetism of 3d or 4d transition metal-doped ZnO (TM0.25Zn0.75O: TM=Ti, Cr, Mn, Fe, Co, Ni, Ru, Pd, and Ag), using the full potential linearized augmented plane method based on general gradient approximation for exchange–correlation potential. The magnetic moments of Ti, Cr, Mn, Fe, Co, Ni, Ru, Pd, and Ag in the systems were calculated to be 1.24, 3.78, 4.93, 4.24, 3.00, 2.00, 0.74, 1.00, and 0.00 μB, respectively. The calculated magnetic moment of Ti is not negligible in marked contrast to the previously calculated zero magnetic moment with Korringa–Kohn–Rostoker. The magnetic moment of a type of oxygen is sizable (up to 0.18 μB).