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Resonant raman scattering in ZnO : Mn and ZnO: Mn : Al thin films grown by RF s...
Cerqueira, M. F.; Vasilevskiy, Mikhail; Oliveira, F.; Rolo, Anabela G.; Viseu, T. M. R.; Campos, J. Ayres de; Alves, E.; Correia, RosárioRaman spectroscopy results obtained under visible (non-resonant) and UV (resonant) excitation for nanocrystalline ZnO, ZnO:Mn and ZnO:Mn:Al thin films grown by radio frequency magnetron sputtering are presented and compared. The origin of the multiple longitudinal optical (LO) phonon Raman peaks, strongly enhanced under resonance conditions, and the effects of the dopants on them are discussed in the framework ...
Optics and children
Costa, Manuel F. M.; Campos, J. Ayres de; Lira, Madalena; Franco, Sandra; Vazquez-Dorrio, José B.Light and Optics are subjects that “naturally” attracts the interest and sympathy of children even from very early ages. In this communication, we present a serie of experiments and support material designed in this hands-on perspective, to be used to introduce the study of light and optics to kindergarten and early basic school students. Our hands-on investigative approach leads the students, aged 4 to 10 year...
Room temperature paramagnetism of ZnO:Mn films grown by RF-sputtering
Oliveira, Filipe André; Cerqueira, M. F.; Vasilevskiy, Mikhail; Viseu, T. M. R.; Campos, J. Ayres de; Rolo, Anabela G.; Martins, J. S.; Sobolev, N. A.ZnO:Mn transparent thin films (thickness b1 μm) with the Mn contents ranging from 1.8 to 3.25 at.% were grown by RF magnetron co-sputtering. The films are nanocrystalline, with wurtzite-structure grains of a typical size of 20 nm and with a preferential orientation of the c-axis perpendicular to the surface. According to the Raman spectroscopy data, Mn mostly substitutes Zn in the lattice sites. In spite of the...
Raman study of doped-ZnO thin films
Cerqueira, M. F.; Rolo, Anabela G.; Viseu, T. M. R.; Campos, J. Ayres de; Arôso, T. de Lacerda; Oliveira, F.; Vasilevskiy, Mikhail; Alves, E.A Raman spectroscopy study of doped versus undoped ZnO layers is presented. The layers were grown by RF magnetron sputtering and the doping with Al, Sb and Mn was achieved by ion implantation with subsequent annealing. First-order Raman response measured under λ=488 nm excitation is discussed. It is shown that doping with any of the impurities used in this work produces a strong enhancement of the longitudinal ...
Electrical and raman scattering studies of ZnO:P and ZnO:Sb thin films
Campos, J. Ayres de; Viseu, T. M. R.; Barradas, N. P.; Alves, E.; Lacerda-Arôso, T. de Lacerda; Cerqueira, M. F.; Rolo, Anabela G.A study on the structure, electrical and optical properties of ZnO thin films produced by r.f. magnetron sputtering and implanted either with phosphorous (P) or antimony (Sb) is reported in this work. Raman spectroscopy, X-ray diffraction, optical transmittance and Hall effect measurements have been employed to characterize the samples. X-ray diffraction and Raman scattering patterns confirm that, after a 500ºC...
ZnO thin films implanted with Al, Sb and P : optical, structural and electrical...
Viseu, T. M. R.; Campos, J. Ayres de; Rolo, Anabela G.; Arôso, T. de Lacerda; Cerqueira, M. F.; Alves, E.In this work we report a study on the structure, optical and electrical properties of P, Sb and Al implanted ZnO thin films that had been produced by r.f. magnetron sputtering. The influence of the different replacing atoms on the structure and properties of the films has been explored. Looking for the best annealing conditions, two different annealing temperatures (300ºC and 500ºC) have been employed. Raman sp...
The annealing effect on structural and optical properties of ZnO thin films pro...
Rolo, Anabela G.; Campos, J. Ayres de; Viseu, T. M. R.; Arôso, T. de Lacerda; Cerqueira, M. F.In this work, a study of the structure and optical properties of undoped ZnO thin films produced by r.f. magnetron sputtering technique as a function of the growth parameters is reported. Modification under annealing conditions is also analysed. Raman spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction and optical transmittance have been used. From the position of the (002) X-ray diffraction peak ...
Study of RFe12−xMox (R =Y, Ho) compounds by neutron powder diffraction, ac susc...
Campos, J. Ayres de; Ferreira, L. P.; Cruz, M. M.; Gil, J. M.; Mendes, P. J.; Ferreira, I. C.; Bacmann, M.; Soubeyroux, J.-L.; Fruchart, D.; Godinho, M.Neutron powder diffraction, magnetization and ac susceptibility measurements were performed on compounds of the series RFe12−xMox (R D Y and Ho, x D 1, 2, 3). The influence of the Mo content on both structural and magnetic properties is discussed. Comparison with published data for different Mo concentrations is made. It is found that the effect of Mo substitution for Fe on structural and magnetic properties ca...
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