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Monitoring the characteristic properties of Ga-doped ZnO by Raman spectroscopy and atomic scale calculations
摘要： We experimentally and theoretically study how the structural and vibrational properties of zinc oxide (ZnO) are modified upon Gallium (Ga) doping. The characteristics of Ga-doped ZnO thin films which are synthesized by sol-gel spin coating method on glass substrates are monitored by using X-ray diffraction (XRD) and Raman scattering measurements. For atomic-level understanding of the experimental findings state-of-the-art density functional theory (DFT) based calculations are also performed. DFT calculations reveal that both the substitution and adsorption of Ga atoms in ZnO are energetically possible and substitutional doping in ZnO is the most favourable scenario. XRD measurements show that all the films are in wurtzite structure and the crystallite size of the films decreases with increasing Ga doping. In addition, Raman analysis show that strong vibrational modes at about 100 and 441 cm?1 are associated with E2low and E2high phonon modes of ZnO, respectively. While the frequency of the E2low downshifts with increasing Ga concentration, the E2high phonon mode is not affected by the Ga doping. Furthermore, EGa phonon branch, stemming from the substituted Ga atoms, emerges at low frequencies. It is also seen that the Raman intensity of the EGa peak linearly increases with increasing Ga concentration. Experimental results on the vibrational properties are in good agreement with the ab initio phonon calculations.
关键词： Thin films,Ga-doped ZnO,XRD,ab initio,Raman spectroscopy
更新于2025-09-23 15:19:57
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AIP Conference Proceedings [Author(s) PROCEEDINGS OF THE 3RD INTERNATIONAL SYMPOSIUM ON CURRENT PROGRESS IN MATHEMATICS AND SCIENCES 2017 (ISCPMS2017) - Bali, Indonesia (26–27 July 2017)] - Effect of nanographene platelets in transition metal-doped ZnO for photocatalytic application
摘要： Both doping and combining ZnO nanoparticles with iron and nanographene platelets (NGP), respectively, have been successfully conducted using the co-precipitation method with various loadings of NGP. The differential thermal analysis and thermogravimetric analysis (DTA/TGA) showed weight loss from the as-prepared samples owing to boundwater and adsorbed water elimination and the combusted effect of NGP in the samples. The structure and morphology or X-ray diffraction (XRD) characterization of the Fe-doped ZnO/NGP nanocomposites exhibited hexagonal wurtzite structure from ZnO and graphite structure from NGP. Raman spectroscopy was also used to observe the frequency modes of the samples. The Fourier transform infrared (FTIR) spectroscopy indicated that increasing NGP amount could decrease the intensity of Fe-O and ZnO vibration mode peaks on the absorption spectra. The photocatalytic test results indicated that certain weight percentage (wt.%) of NGP could enhance the performance of Fe-doped ZnO to degrade methylene blue dye in an aqueous solution under UV light irradiation. To obtain the main active species in the photocatalytic activity, additional scavengers were added in the solution. We also varied the dye and dosage concentration to determine the maximum condition in the photocatalytic process.
关键词： photocatalytic,nanographene platelets,Fe-doped ZnO
更新于2025-09-23 15:19:57
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Fabrication of nanoheterostructures of boron doped ZnO-MoS2 with enhanced photostability and photocatalytic activity for environmental remediation applications
摘要： In this work, we have developed two dimensional (2D) nanosheets-nanoparticles (0D) nanoheterostructures of boron-doped ZnO nanoparticles loaded over MoS2 nanosheets with enhanced photocatalytic activity for pollutant removal. A series of nanoheterostructures with varying amount of MoS2 nanosheets were prepared using facile hydrothermal method and characterized by x-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM) and high resolution transmission electron microscopy (HRTEM) techniques to confirm there successful synthesis. The optimized nanoheterostructure photocatalyst with 1 wt% of MoS2 nanosheets (BZM1) exhibits superior photocatalytic activity for pollutant removal under visible light illumination. The superior photocatalytic activity of BZM1 nanoheterostructure has been supported by photoluminescence (PL) studies which show the remarkably decreased PL intensity signifying the low recombination rate of photogenerated charge carriers. In addition, the formation of 0D-2D heterojunction plays a significant role in enhancing the photocatalytic activity by accelerated photogenerated charge carriers separation in space and ultimately improved photocatalytic activity. Furthermore, the plausible photocatalytic mechanism has been discussed in detail on the basis of active species trapping experiment which validate the significant role of holes and hydroxyl radicals in degradation process. Overall, this work paves way for the facile fabrication of 0D-2D nanoheterostructures for diverse applications.
关键词： Boron doped ZnO,charge transfer,B-ZnO-MoS2 nanoheterostructures,environmental remediation,photocatalysis
更新于2025-09-19 17:15:36
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Effect of position and concentration of Li on ZnO physical properties : Density functional investigation
摘要： In this paper, we study the effect of Li position on the physical properties of Li doped ZnO with different concentrations (6.25%,12.5% and 18.75%), by using density functional theory and Boltzmann transport theory. In this work, two possible configurations of Li-doped ZnO are considered : substitution of Zn by Li atom (LiZn), and Li takes the interstitial position (Lii). It is found found that the position and the concentration of Li play an important role in determining the suitable applications for Li doped ZnO. It is also shown that the obtained results are in good agreement with experimental studies.
关键词： Li doped ZnO,Electronic Structure,First principles study,interstitial.,substitution
更新于2025-09-19 17:15:36
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Room temperature ferromagnetism in ball milled Cu-doped ZnO nanocrystallines: an experimental and first-principles DFT studies
摘要： Experimental and theoretical studies on the room temperature ferromagnetism of ball milled Zn0.95Cu0.05O nanocrystalline, were reported. X-ray diffraction analysis reveals that the most dominant crystalline phase is hexagonal wurtzite with presence of weak peaks due to Cu and CuO. Rietveld analysis indicated that the crystallite size decreases with increasing milling time, while the strain enhanced with milling time. Magnetic measurements using SQUID expose remarkable room temperature ferromagnetic ordering for milled samples. The physical origin of the ferromagnetism order has been explained using a bound magnetic polaron model. Theoretical calculations based on First principles methods were employed to calculate the electronic structures and magnetic properties of Cu doping and zinc and oxygen vacancies behavior of Zn1?xCuxO. It was found that a Cu dopant leads to induce magnetism and exhibits an increasing of magnetic moment when Zn vacancy are introduced.
关键词： Room temperature ferromagnetism,Ball milled Cu-doped ZnO,Magnetic properties,Nanocrystalline,First-principles DFT
更新于2025-09-19 17:13:59
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Low-temperature Interfacial Engineering for Flexible CsPbI2Br Perovskite Solar Cells with High Performance Beyond 15%
摘要： All-inorganic cesium lead halide (CsPbX3) perovskites exhibit superior thermal stability compared to the organic-inorganic hybrid counterparts. The power conversion efficiency (PCE) of CsPbI2Br perovskite solar cells (PSCs) has been over 16%. However, the high-temperature annealing limits its feasibility on flexible devices. Here, low-temperature processed flexible CsPbI2Br PSCs are designed by introducing Al-doped ZnO (AZO) as an electron-transport layer and tert-butyl cyanoacetate (t-BCA) as a passivation layer. The thickness-insensitive AZO significantly enhances the quality of perovskite films and the reproducibility of the PSCs. As well the t-BCA can effectively passivate the trap states and suppress charge recombination of CsPbI2Br films. The as-optimized flexible CsPbI2Br PSCs exhibits a high PCE of 15.08% (with the active area of 0.1 cm2), which is one of the highest efficiency for flexible all-inorganic PSCs. The devices show outstanding stability, retaining 93% of the original PCE after being stored 60 days, 91% and 86% of the initial efficiency after continuously heating 360 hours at 85 oC and stored under 65% RH for 30 hours, respectively. In addition, the PSCs exhibits excellent mechanical stability, remains 85% of original value after 1000 bending cycles at a curvature radius of 3 mm.
关键词： perovskite solar cells,tert-butyl cyanoacetate,passivation layer,All-inorganic cesium lead halide,flexible devices,low-temperature processed,Al-doped ZnO
更新于2025-09-19 17:13:59
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Synthesis, characterization and UV photodetector application of Sb-doped ZnO nanowires
摘要： Sb-doped ZnO nanowires with hexagonal wurtzite structures have been synthesized via chemical vapor deposition method, and the main charge state of Sb dopants is Sb5+. The photoluminescence spectra demonstrate the existence of shallow acceptors, SbZn-2VZn complexes in all probability. On the other hand, Sb doping caused more native and impurity donors in Sb-doped ZnO nanowires. Then, field effect transistors of single Sb-doped ZnO nanowire were fabricated and the transport properties shows n-type conductivity. The competition between shallow acceptors and donors, and the influence of Sb valency need to be investigated further to obtain stable Sb-doped p-type ZnO. At last, we have shown the potential application of Sb-doped ZnO nanowires for nanoscale UV photodetector.
关键词： field effect transistors,UV photodetector,Sb-doped ZnO nanowires,photoluminescence,chemical vapor deposition
更新于2025-09-16 10:30:52
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SYNTHESIS AND CHARACTERIZATION OF La-DOPED ZnO (La:ZnO) FILMS FOR PHOTODETECTORS
摘要： In this work, the La-doped ZnO thin films were fabricated with different La concentrations by the use of sol–gel technique to synthesize the photodevice. The transparent metal oxide La-doped ZnO thin films were grown on glass and p-Si substrates using spin coating technique. Optical, surface morphology and electrical characterization of the fabricated Al/p-Si/La:ZnO/Al devices have been performed using I–V and C/G–V characteristics under dark and different illumination conditions. Herein, from I–V characteristics, the crucial electronic parameters such as barrier height, ideality factor and series resistance were investigated. The photodevice transient photocurrent increases with the increase of illumination intensity. The current ratios of Ion/Ioff were calculated for the fabricated devices. Among the devices, the highest photoresponse was found to be about 2186 for the Al/p-Si/La(0.5 wt.%):ZnO/Al structure. The Rs–V behavior of fabricated device confirms the presence of interface states. The obtained results and photoresponse behaviors suggested that Al/p-Si/La:ZnO/Al devices can enhance the applications in optoelectronic devices such as photodetectors.
关键词： sol–gel,photoresponse,photodetector,doped ZnO,Electrical characteristics
更新于2025-09-16 10:30:52
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A Rapid Synthesis of Vertically Aligned Taper-Like K-Doped ZnO Nanostructures to Enhance Dye-Sensitized Solar Cell Efficiency
摘要： Large-scale K-doped ZnO nanotapers were successfully grown on an indium tin oxide (ITO) substrate using a facile electrochemical route. The structural and morphologic analysis exhibited that the K-doped ZnO nanostructures had a nanotaper morphology and strong preferential [0001] c-axis direction with a hexagonal polycrystalline structure. The optical results show that the incorporation of K+ ions as the donors in a ZnO lattice leads to substantial modulation of the band gap structure of ZnO nanotapers, which results in a redshift in the ultraviolet emission peaks. The considerable enhancement of performance in K-doped ZnO-based dye-sensitized solar cells (DSSCs) can be related to the doping structure, which leads to higher dye loading (3.34 9 10(cid:2)8 mol/cm2). The good photovoltaic behavior of the K-doped ZnO nanotapers can be attributed to the higher surface-to-volume ratio and large K-doped ZnO nanotaper/ITO interfacial band bending, indicating the potential of a low-temperature aqueous electrochemical approach to synthesizing doped ZnO nanotapers for DSSCs.
关键词： K-doped ZnO,nanotapers,dye-sensitized solar cells,electrochemical route,band gap modulation
更新于2025-09-16 10:30:52
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Ultraviolet photodetectors based on doped ZnO films
摘要： In this paper, we report the realization of ultraviolet (UV) photodetector based on doped ZnO films. The ZnO p-n junction was fabricated on indium tin oxide (ITO) coated glass, which consists of n-type and p-type layers based on Ga-doped (2 at.%) and N-doped (20 at.%) ZnO films, respectively. The current-voltage (IV) characteristics, photosensitivity, photoresponsitivity, and photocurrent gain were derived to determine the performance of the device. At 5 V reverse bias, the ZnO-based UV photodetector exhibits photosensitivity of 10.9, photoresponsivity of 2.1 × 10-2 AW-1, and photoconductive gain of 7.2 × 10-2.
关键词： ultraviolet photodetectors,sol-gel spin coating,p-n junction,doped ZnO films
更新于2025-09-12 10:27:22