The doping of oxide-based semiconductors with rare-earth ions may serve as an alternative to transition metal doping with the possibility of room-temperature ferromagnetism. Here, highly transparent thin films of ZnO doped with a rare-earth element, Gd, were prepared via a sol-gel-derived precursor. A series of Gd-doped ZnO films with different Gd concentrations (0 to 8 at.%) were deposited onto glass substrates. XRD analysis revealed that the FWHM of the diffraction peaks increased with the increase of Gd composition which may indicate that the Gd incorporation decreased the crystallinity. However no new peaks associated with the formation of secondary phases such as GdO and Gd metal clusters were detected. The MFM images were seen to be more pronounced with the incorporation of Gd ions where we could clearly observe the magnetic signals at room temperature especially for the samples with higher Gd doping of 4 and 8 at.% Gd. Evidently, the magnetic domain size exhibited a significant increase with the increase of Gd composition in contrast to the undoped sample.
A simple and cost effective method using a thermal oxidation process for synthesizing cupric oxide (CuO) nanostructures is demonstrated in this paper. Using elevated temperatures ranging from 100°C to 400°C, the optimum formation of CuO composition indicated by an X-ray diffraction (XRD) was obtained at 400°C. Then, the effects of gas flow rates (ranging from 1 to 10 kPa) on the formation of CuO nanorods were investigated using a field emission scanning electron microscope (FESEM). It was found that at higher gas flow rate, the formation of CuO nanorods was obviously observed. The current-voltage (I-V) characteristic obtained from an I-V measurement system shows that diode characteristic has been formed with threshold voltage (Vth) of 0.9 V and breakdown voltage (VB) of-5 V. The mechanism of structural changes will be discussed in details.
Abstract.ZnO nanorods (NRs) arrays were synthesized by chemical solution deposition (CSD) method on commercial glass substrate with ZnO thin film act as seed layer prepared by sol-gel spin coating. The effect of annealing temperature of 150°C, 250°C and 500°C, respectively, on the structural growth was investigated. The observation reveals the structural improvement as the annealing temperature increased. The influence of gadolinium doping to ZnO NRs arrays wasexplored upon the structural and optical features. The FESEM imaging along with XRD, AFM and UV-Vis analysis were conducted to dissect the information gained by performing a study case on various gadolinium doping content in the range of 1 at. % to 4 at. %. Based on the results, the correlation between the doping content were drawn in details in this paper.
IntroductionZinc oxide (ZnO) is well known in the scientific community to possess a lot of advantages in its nature, making it as one of the most prominent material for a variety of electronic and optoelectronic applications [1]. However on the contrary, doped ZnO can hold some very different properties compared to that of pure ZnO. Group III elements, i.e. Ga, Al, and In can be used as ntype dopant in ZnO, have been generally recognized to influence the optical and also the electrical properties of the materials [2].Other elements of rare earth group, i.e. Ce, Er, Eu, La, Tb, Tm, Yb, and Dy as p-type dopant to ZnO, have also attracted significant attention among the community due to their unique optical properties which give to intense emission peaks in the visible and near infrared range [3].Hence, the electrical conductivity, type of conduction and band gap range, including the magnetic characteristics of the nanomaterial can be manipulated through doping. Therefore, doping effect can enhance the present properties of ZnO and provides space for new applications possible.
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