Hydrothermal growth and characterization of Al-doped ZnO nanorods

Shrisha, B; Bhat, Shashidhara; Kushavah, Dushyant; Naik, K. Gopalakrishna

doi:10.1016/j.matpr.2016.04.061

Cited by 29 publications

(15 citation statements)

References 16 publications

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“…Simultaneously to the changes observed for d and σ SE , ε ∞ values of the ZnO damaged layer are found to decrease with the Ar + fluence. In comparison, in the virgin ZnO substrate, we obtained a value of ε ∞ = 2.032, which is in good agreement with data reported for ZnO grown by hydrothermal synthesis [44]. Similar behaviour was found for E CPPB , which redshifts from 2.9 eV down to 1.5 eV with the fluence.…”

Section: Parametersupporting

confidence: 90%

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Modelling of Optical Damage in Nanorippled ZnO Produced by Ion Irradiation

et al. 2019

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Here, we report on the production of nanoripples on the surface of ZnO bulk substrates by ion beam erosion with 20 keV Ar + ions at an oblique incidence (60 • ). The ripple patterns, analyzed by atomic force microscopy, follow a power law dependence for both the roughness and the wavelength. At high fluences these ripples show coarsening and asymmetric shapes, which become independent of the beam direction and evidence additional mechanisms for the pattern development. The shallow damaged layer is not fully amorphized by this process, as confirmed by medium energy ion scattering. A detailed study of the damage-induced changes on the optical properties was carried out by means of spectroscopic ellipsometry. Using a 3-layer model based on Tauc-Lorenz and critical point parameter band oscillators, the optical constants of the damaged layer were determined. The results showed a progressive reduction in the refractive index and enhanced absorption below the bandgap with the fluence.Crystals 2019, 9, 453 2 of 12 with identical crystal structure (wurtzite) and are suitable for applications in optoelectronics, including the fabrication of light emitting diodes and laser diodes [7,8]. However, since commercial GaN-based devices are already available in the global market, considerable interest has shifted to other potential uses of ZnO.The existing reports on the surface modification of ZnO mainly refer to focused ion beams [9] or laser ablation processes [10]. Only recently, some works have reported ripple formation on ZnO when implanting with 10 keV O + ions [11]. More research is needed to understand the physical processes that take place when this kind of radiation resistant material is irradiated, especially with respect to the damage formation and the particular role of preferential sputtering. In this regard, there is also a lack of reliable optical models to explain the evolution of the damage in these semiconductors, which can be helpful to monitor the implantation effects. One technique able to provide such information is spectroscopic ellipsometry (SE), which has been used for the determination of damage profiles in different semiconductors, such as Si [12] or GaAs [13]. However, these models are very specific for every semiconductor and do not take into account the development of very rough surfaces during the implantation: the typical case when producing ripple patterns at high fluences.Considering this scenario, the main goal of this work was to assess the formation of ripple patterns in bulk ZnO by IBS at medium energy (20 keV) using Ar + ions. We analysed the ripple patterns produced by oblique irradiation regarding the roughness, ripple wavelength, and order. In order to evaluate the ion beam modification of the material, we took advantage of SE to model both the optical damage and the roughening of the surface, and to extract the main optical parameters after the irradiation. Materials and MethodsBulk c-plane one-side polished ZnO crystals (supplied by CrysTec and produced by hydrothermal synthesis, Berli...

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Section: Parametersupporting

confidence: 90%

“…Crystals 2019, 9, x FOR PEER REVIEW 9 of 12 synthesis [44]. Similar behaviour was found for ECPPB, which redshifts from 2.9 eV down to 1.5 eV with the fluence.…”

Section: Parametersupporting

confidence: 69%

Modelling of Optical Damage in Nanorippled ZnO Produced by Ion Irradiation

et al. 2019

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“…The ZnO nanorods were deposited on the AZO seed layer, which showed a stronger diffraction peak corresponding to the (002) plane, growing along the c-axis perpendicular to the substrate surface; weak (100), (101), (102), and (110) peaks were also observed. When Al(NO 3 ) 3 •9H 2 O was added to the aqueous solution to form the AZO nanosheets, the reduced (002) peak intensity indicated that the AZO nanosheets did not exhibit an improved crystallinity [31,32]. Figure 4 shows the Field-Emission Scanning Electron Microscope (FE-SEM) forms for the ZnO nanorods and AZO nanosheets.…”

Section: Instrumentsmentioning

confidence: 99%

Dye-Sensitized Solar Cells Using Aluminum-Doped Zinc Oxide/Titanium Dioxide Photoanodes in Parallel

Chou

Chang

et al. 2019

Energies

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In this study, both zinc oxide (ZnO) nanorods and aluminum-doped zinc oxide (AZO) nanosheets were deposited by hydrothermal growth on fluorine-doped tin oxide (FTO) glass. After a photoanode was added to ZnO nanorods or AZO nanosheets, the photovoltaic conversion efficiency (PCE) increased due to improved electron transport and enhanced dye absorption. The improvement in electron transport was verified by electrochemical impedance spectroscopy (EIS), and the increase in dye absorption was verified by ultraviolet-visible spectroscopy. Both of these factors facilitated an increase in PCE. Parameters for dye-sensitized solar cells (DSSCs) using ZnO nanorods/TiO2 and AZO nanosheets/TiO2 photoanodes were tested and the results were recorded using EIS. The results indicated that the addition of the ZnO nanorods increased the short-circuit current density (Jsc) from 9.07 mA/cm2 to 10.91 mA/cm2, the open circuit voltage (Voc) from 0.68 V to 0.70 V, and the PCE from 3.70% to 4.73%, respectively. When the DSSCs were produced in a parallel silver-grid device, the results showed that PCE could be increased from 3.67% to 4.04% due to the reduction in connection resistance.

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“…Recently, one-dimensional semiconductor nanostructures have been one of the focuses of current research in physics, chemistry, and materials science due to their significance in both fundamental knowledge and technological applications [ 1 ]. Among those semiconductor nanomaterials, ZnO has received broad attention for potential applications in short wavelength optoelectronic devices, owing to its wide direct band gap of 3.37 eV at room temperature and large exciton binding energy of 60 meV [ 2 ]. More attractively, nanostructured ZnO has a diverse group of growth morphologies, which can be widely used to construct nanoscale devices for various needs.…”

Section: Introductionmentioning

confidence: 99%

“…In order to develop devices with desired functionality, the properties of ZnO have been tuned by various approaches [ 3 ]. Among them, doping is an effective way to change or adjust the electronic and optical properties of materials [ 2 ]. For optoelectronic applications, doping of ZnO has to be done to achieve the ideal properties and device’ performance [ 4 , 5 ].…”

Section: Introductionmentioning

confidence: 99%

Microstructure and Doping/Temperature-Dependent Photoluminescence of ZnO Nanospears Array Prepared by Hydrothermal Method

et al. 2018

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Al-doped ZnO nanospears were prepared by a hydrothermal method. The crystalline structure and photoluminescence properties of ZnO nanospears were characterized for investigating the effect of Al doping on the properties of ZnO nanospears. ZnO nanospears grow preferentially along the c-axis and have a fine tip. Al doping reduces the length of ZnO nanospears. In room temperature, photoluminescence spectra of Al-doped ZnO nanospears, a near band edge emission (~3.16 eV), and a violet emission (~2.91 eV) exhibit a strong doping-dependent characteristic and a temperature-independent characteristic, while deep level emission peak shows a temperature-dependent characteristic. In variable temperature, photoluminescence spectra near band edge emission (~3.31 eV) and its fine structures were observed when the measurement temperature is less than 57 K, and it shows an obvious temperature-dependent characteristic. The thermal quenching of this near band edge emission should be attributed to exciton scattering by defects and the presence of a high concentration of defects in Al-doped ZnO nanospears.

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Hydrothermal growth and characterization of Al-doped ZnO nanorods

Cited by 29 publications

References 16 publications

Modelling of Optical Damage in Nanorippled ZnO Produced by Ion Irradiation

Modelling of Optical Damage in Nanorippled ZnO Produced by Ion Irradiation

Dye-Sensitized Solar Cells Using Aluminum-Doped Zinc Oxide/Titanium Dioxide Photoanodes in Parallel

Microstructure and Doping/Temperature-Dependent Photoluminescence of ZnO Nanospears Array Prepared by Hydrothermal Method

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