Optical and electrical properties of p-type Ag-doped ZnO nanostructures (original) (raw)
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ACS applied materials & interfaces, 2015
Doping ZnO nanowires (NWs) by group IB elements is an important challenge for integrating nanostructures into functional devices with better and tuned performances. The growth of Ag-doped ZnO NWs by electrodeposition at 90 °C using a chloride bath and molecular oxygen precursor is reported. Ag acts as an electrocatalyst for the deposition and influences the nucleation and growth of the structures. The silver atomic concentration in the wires is controlled by the additive concentration in the deposition bath and a content up to 3.7 atomic % is reported. XRD analysis shows that the integration of silver enlarges the lattice parameters of ZnO. The optical measurements also show that the direct optical bandgap of ZnO is reduced by silver doping. The bandgap shift and lattice expansion are explained by first principle calculations using the density functional theory (DFT) on the silver impurity integration as an interstitial (Agi) and as a substitute of zinc atom (AgZn) in the crystal la...
Optical properties of group-I-doped ZnO nanowires
Ceramics International, 2014
Undoped and group-I elements doped ZnO nanowires were synthesized using a thermal evaporation method. Field emission scanning electron microscopy (FESEM) results showed that, the undoped ZnO nanowires were ultra-long with uniform diameters. On the other hand, the length of the doped ZnO nanowires was in the range of some hundred of nanometers. X-ray diffraction (XRD) patterns clearly indicated hexagonal structures for all of the products. X-ray photoelectron spectroscopy (XPS) studies confirmed the oxidation states of Li, Na, K, in the ZnO lattice. An asymmetric O 1s peak indicated the presence of oxygen in an oxide layer. The effect of doping on the optical band-gap and crystalline quality was also investigated using photoluminescence (PL), UV-vis, and Raman spectrometers. The Raman spectra of the products indicated a strong E 2 (high) peak. The PL spectra exhibited a strong peak in the ultraviolet (UV) region of the electromagnetic spectrum for all of the ZnO nanowires. The UV peak of the doped ZnO nanowires was red-shifted compared to the undoped ZnO nanowires. In addition, the UV-vis spectra of the samples showed similar results compared to the PL results.
Effects of silver impurity on the structural, electrical, and optical properties of ZnO nanowires
Nanoscale Research Letters, 2011
1, 3, and 5 wt.% silver-doped ZnO (SZO) nanowires (NWs) are grown by hot-walled pulsed laser deposition. After silver-doping process, SZO NWs show some change behaviors, including structural, electrical, and optical properties. In case of structural property, the primary growth plane of SZO NWs is switched from (002) to (103) plane, and the electrical properties of SZO NWs are variously measured to be about 4.26 × 106, 1.34 × 106, and 3.04 × 105 Ω for 1, 3, and 5 SZO NWs, respectively. In other words, the electrical properties of SZO NWs depend on different Ag ratios resulting in controlling the carrier concentration. Finally, the optical properties of SZO NWs are investigated to confirm p-type semiconductor by observing the exciton bound to a neutral acceptor (A0X). Also, Ag presence in ZnO NWs is directly detected by both X-ray photoelectron spectroscopy and energy dispersive spectroscopy. These results imply that Ag doping facilitates the possibility of changing the properties in...
Ag-doped ZnO nanorods synthesized by two-step method
Chinese Physics B, 2012
A two-step method is adopted to synthesize Ag-doped ZnO nanorods. A ZnO seed layer is first prepared on a glass substrate by thermal decomposition of zinc acetate. Ag-doped ZnO nanorods are then assembled on the ZnO seed layer using the hydrothermal method. The influences of the molar percentage of Ag ions to Zn ions (RAg/Zn) on the structural and optical properties of the ZnO nanorods obtained are carefully studied using X-ray diffractometry, scanning electron microscopy and spectrophotometry. Results indicate that Ag ions enter into the crystal lattice through the substitution of Zn ions. The (002) c-axis-preferred orientation of the ZnO nanorods decreases as RAg/Zn increases. At RAg/Zn > 1.0%, ZnO nanorods lose their c-axis-preferred orientation and generate Ag precipitates from the ZnO crystal lattice. The average transmissivity in the visible region first increases and then decreases as RAg/Zn increases. The absorption edge is first blue shifted and then red shifted. The inf...
Preparation and characterisation of silver doped ZnO nanostructures
International Journal of Nanotechnology, 2013
ZnO was prepared by hydrothermal method. The result of scanning electron microscopy showed that the materials had nanorod structures. Ag-doped ZnO was prepared by UV-photoreduction respectively. Crystalline phases and optical absorption of the prepared samples were determined by X-ray diffraction, Raman spectrum and UV-visible spectrophotometer. X-ray analyses reveals that Ag doped ZnO crystallises in hexagonal wurtzite structure. The incorporation of Ag + in the site of Zn 2+ provoked an increase in the size of nanocrystals as compared to pure ZnO. The morphologies of materials have been investigated by using scanning electron microscopy. The photocatalytic property and photoluminescence property of materials were considered.
Structural and Optical Properties of Ag and In–Doped ZnO Nanoparticles Synthesized by Sol-Gel Method
In this paper, we have reported the synthesis of silver and Indium co-doped ZnO nanoparticles at low temperature by sol-gel method were found to have hexagonal structure. This method is simple and cost effective. The crystallite size, structure, elemental composition, surface morphology, UV absorbance and band gap, optical properties and functional group analysis were characterized by X-ray diffraction (XRD), Fourier transform Infrared Spectroscopy (FTIR), Ultra-visible spectroscopy (UV),Photoluminescence spectroscopy(PL) Scanning Electron Microscopy (SEM), Transmission Electron Microscopy(TEM), Energy Dispersive X–ray analysis (EDAX). XRD analysis reveals that all samples crystallizes in polycrystalline nature with hexagonal wurtzite and exhibit no other impurity phases. The variation in the intensities of the XRD lines is correlated with Ag and In incorporation in the ZnO lattice. From the XRD data, we have calculated dislocation density, crystallite size, lattice parameters, c/a ratio, ZnO bond length, volume of the unit cell and strain. FTIR spectroscopy was carried out to analyze the functional groups corresponding to the Zn-O bands in the samples. The prepared ZnO nano crystallite size lies in the range of (10-20nm). SEM analysis confirms that the nanoparticles sample show the formation of nanorods.TEM micrograph of the samples has been found to be spherical with irregular particle size distribution. Optical properties were studied by UV-Visible spectrophotometer. The energy gap is found to decrease from 3.28eV, 3.18eV and 3.06eV with increasing doping concentration.
Optical and Quantum Electronics, 2020
An investigation of room-temperature sol-gel synthesis Ag doped ZnO nano-particles are reported here. The effect of silver concentration (2, 4, 6, 8 and 10 at. wt.%) on the morphology, structural and optical properties of the Ag doped ZnO nanoparticles are studied. XRD analysis displays the hexagonal wurtzite structure. The crystallite size was found to decrease in the range 36.95-28.11 nm with the increase in Ag dopant percentage. With enhancement in the Ag contents, the crystallite size decreases and specific surface area increases which suggest their use in biological science and photocatalysis. Surface morphology shows that grains are irregular, cuboid, linear and spherical shaped nanoparticles with slightly varying sizes. The Ag doped ZnO nanoparticles show interesting properties, which are modified by the change of the grain size with increase in Ag dopant percentage. The band gap of the nanoparticles decreases with increase in Ag doping where 10 at. wt.% Ag dopant nanoparticles have a notably lower band gap than that of undoped ZnO (3.37 eV). Photoluminescence spectra has shown the violet shift emission bands. The optical properties predict the use of Ag doped ZnO nanoparticles in solar cells, optoelectronics, spintronics and wastewater treatment.
Nanocrystals of undoped and silver doped zinc oxide (Zn 1-x Ag x O (where x = 0.00 to 0.05) were synthesized by coprecipitation method. Crystalline phases and optical absorption of prepared samples were determined by X-ray diffraction and UV-visible spectrophotometer. The average particles size was determined from X-ray line broadening. X-ray analyses reveals that Ag doped ZnO crystallizes in hexagonal wurtzite structure. The incorporation of Ag + in the place of Zn 2+ provoked an increase in the size of nanocrystals as compared to undoped or pure ZnO. Optical absorption measurement indicates red shift in the absorption band edge upon Ag doping. The band gap values of as prepared undoped and doped with silver samples are found to decrease with increase in temperature from 300 to 800 o C.
Optical Investigation of ZnO Nanowires
Acta Physica Polonica A, 2010
In this study we report the application of synchrotron X-ray fluorescence, photoluminescence and Raman scattering techniques to the analysis of the incorporation of impurities in unintentionally doped ZnO nanowires. Highly ordered one-dimensional ZnO arrays were fabricated by an oxidation process of Zn metal electrodeposited in nanoporous anodic alumina template. X-ray fluorescence data show the contribution of residual elements into the ZnO nanowires growth. A rough analytical quantification of the main light and heavy chemical contents derives impurity concentrations below 1%. The optical efficiency of ZnO nanowires is strongly affected by non-radiative centers up to temperatures as low as 100 K. The photoluminescence was found to be totally dominated by optical transitions associated with the anodic alumina template. Finally, the Raman scattering provides no evidence of local vibrational modes or secondary phases, but it shows the unambiguous signature of the ZnO hexagonal phase.
Korean Journal of Chemical Engineering, 2006
Synthesis of ZnO nanowires was achieved on Si(100) substrate by the thermal evaporation of high purity metallic zinc powder without the use of any metal catalyst or additives. The diameter and length of the as-grown nanowires were in the range of 20–35 nm and few micrometers, respectively. The shapes and sizes of ZnO nanowires were dependent on the growth time. The high resolution transmission electron microscopy and selected area electron diffraction patterns indicated that the as-grown products are single crystalline with wurtzite hexagonal phase. Room temperature photoluminescence studies exhibited a strong UV emission and a suppressed green emission, confirming the good optical properties for the deposited nanowires.