Optical and magnetic characterization of transition metal ion doped ZnO microspheres synthesized via laser ablation in air
TL;DR: In this paper, the synthesis of transition metal doped (TM) ZnO micropsheres using doped znO sintered targets containing Mn 1% dopant was reported.
Abstract: We report the synthesis of transition metal doped (TM) ZnO micropsheres using doped ZnO sintered targets containing Mn 1% dopant. Transition metals are prospective materials for p type acceptor doping in ZnO. Structural and morphology study were conducted using XRD (X-ray diffraction), SEM and Raman spectroscopy. Room temperature Photoluminescence (PL) spectra of the fabricated ZnO microspheres were measured, at an excitation wavelength of 355 nm. In our study, smooth spherical shaped micro particles with different diameters ranging from ~1 to 3 μm were grown in different substrates by using a pulsed N 3+: YAG laser. SEM (Scanning Electron Microscopy) images show the presence of uniform smooth surfaced spheres. Raman scattering measurements from the synthesised samples at 532 nm wavelength excitation provide confirms the wurtzite structure of the fabricated undoped and TM doped ZnO microsphere. The doped microspheres exhibited UV whispering gallery modes (WGM) cavity lasing by optical pumping. Magnetic measurements from TM doped ZnO microparticles using vibrating sample magnetometer (VSM) are in progress.
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TL;DR: In this article, the status of zinc oxide as a semiconductor is discussed and the role of impurities and defects in the electrical conductivity of ZnO is discussed, as well as the possible causes of unintentional n-type conductivity.
Abstract: In the past ten years we have witnessed a revival of, and subsequent rapid expansion in, the research on zinc oxide (ZnO) as a semiconductor. Being initially considered as a substrate for GaN and related alloys, the availability of high-quality large bulk single crystals, the strong luminescence demonstrated in optically pumped lasers and the prospects of gaining control over its electrical conductivity have led a large number of groups to turn their research for electronic and photonic devices to ZnO in its own right. The high electron mobility, high thermal conductivity, wide and direct band gap and large exciton binding energy make ZnO suitable for a wide range of devices, including transparent thin-film transistors, photodetectors, light-emitting diodes and laser diodes that operate in the blue and ultraviolet region of the spectrum. In spite of the recent rapid developments, controlling the electrical conductivity of ZnO has remained a major challenge. While a number of research groups have reported achieving p-type ZnO, there are still problems concerning the reproducibility of the results and the stability of the p-type conductivity. Even the cause of the commonly observed unintentional n-type conductivity in as-grown ZnO is still under debate. One approach to address these issues consists of growing high-quality single crystalline bulk and thin films in which the concentrations of impurities and intrinsic defects are controlled. In this review we discuss the status of ZnO as a semiconductor. We first discuss the growth of bulk and epitaxial films, growth conditions and their influence on the incorporation of native defects and impurities. We then present the theory of doping and native defects in ZnO based on density-functional calculations, discussing the stability and electronic structure of native point defects and impurities and their influence on the electrical conductivity and optical properties of ZnO. We pay special attention to the possible causes of the unintentional n-type conductivity, emphasize the role of impurities, critically review the current status of p-type doping and address possible routes to controlling the electrical conductivity in ZnO. Finally, we discuss band-gap engineering using MgZnO and CdZnO alloys.
2,962 citations
TL;DR: The most important methods of preparation of ZnO divided into metallurgical and chemical methods are presented and possible applications in various branches of industry: rubber, pharmaceutical, cosmetics, textile, electronic and electrotechnology, photocatalysis were introduced.
Abstract: Zinc oxide can be called a multifunctional material thanks to its unique physical and chemical properties. The first part of this paper presents the most important methods of preparation of ZnO divided into metallurgical and chemical methods. The mechanochemical process, controlled precipitation, sol-gel method, solvothermal and hydrothermal method, method using emulsion and microemulsion enviroment and other methods of obtaining zinc oxide were classified as chemical methods. In the next part of this review, the modification methods of ZnO were characterized. The modification with organic (carboxylic acid, silanes) and inroganic (metal oxides) compounds, and polymer matrices were mainly described. Finally, we present possible applications in various branches of industry: rubber, pharmaceutical, cosmetics, textile, electronic and electrotechnology, photocatalysis were introduced. This review provides useful information for specialist dealings with zinc oxide.
1,403 citations
TL;DR: A comprehensive overview of the progress that has been made within the context of 1D ZnO nanostructures synthesized via wet chemical methods can be found in this paper, where the synthetic methodologies and corresponding growth mechanisms, different structures, doping and alloying, position-controlled growth on substrates, and finally, their functional properties as catalysts, hydrophobic surfaces, sensors, and in nanoelectronic, optical, optoelectronics, and energy harvesting devices.
Abstract: One-dimensional (1D) ZnO nanostructures have been studied intensively and extensively over the last decade not only for their remarkable chemical and physical properties, but also for their current and future diverse technological applications. This article gives a comprehensive overview of the progress that has been made within the context of 1D ZnO nanostructures synthesized via wet chemical methods. We will cover the synthetic methodologies and corresponding growth mechanisms, different structures, doping and alloying, position-controlled growth on substrates, and finally, their functional properties as catalysts, hydrophobic surfaces, sensors, and in nanoelectronic, optical, optoelectronic, and energy harvesting devices.
1,127 citations
TL;DR: The green and yellow luminescence centres in ZnO and Mn-doped ZnOs are investigated in this article, and it seems that a VZn · V0 divacancy exists, and that luminecence is due to interstitial zinc and oxygen.
Abstract: The green and yellow luminescence centres in ZnO and Mn-doped ZnO are investigated. Water vapour enhances green luminescence of ZnO in the surface, and causes a two band luminescence phenomenon (green and yellow35in the bulk. Mn behaves as quencher for both the green and the yellow luminescence of ZnO. Positron lifetime measurements show the existence of at least two distinct vacancy-type defects in all materials. At the present time it seems that a VZn · V0 divacancy exists, and that luminescence is due to interstitial zinc and oxygen.
658 citations
TL;DR: In this paper, the influence of manganese, an effective dopant to obtain ZnO diluted magnetic semiconductors, on the lattice dynamics of ZnOs was investigated.
Abstract: Raman scattering has been used to study the influence of manganese, an effective dopant to obtain ZnO diluted magnetic semiconductors, on the lattice dynamics of ZnO. It is found that Mn doping increases the lattice defects and induces two Raman vibration modes of 275 and 526cm−1. On the other hand, high temperature (TC higher than 350K) ferromagnetism is observed in Zn1−xMnxO (x⩽0.02) nanoparticles. It is found that the ferromagnetism of Zn1−xMnxO nanoparticles is strongly related to defects in ZnO.
211 citations