Photoluminescence and damage recovery studies in Fe-implanted ZnO single crystals

Monteiro, T.; Boemare, C.; Soares, M.J.; Rita, E.; Alves, E.

doi:10.1063/1.1573341

Cited by 58 publications

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“…The study of the production and recovery process of these defects is therefore very important for a successful doping. There have been a number of studies on the defects induced by ion implantation in ZnO using Rutherford backscattering, 12,13 photoluminescence and cathodoluminescence, 14 deep-level transient spectroscopy, 15 secondary-ion-mass spectrometry, 16 and other electrical characterization methods. 17,18 In addition to these methods, positron annihilation spectroscopy has recently emerged as a powerful tool for the study of vacancy-type defects in semiconductors.…”

Section: Introductionmentioning

confidence: 99%

Production and recovery of defects in phosphorus-implanted ZnO

Chen

Kawasuso

et al. 2004

Journal of Applied Physics

132

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Articles you may be interested inReuse of AIP Publishing content is subject to the terms at: https://publishing.aip.org/authors/rights-and-permissions. Phosphorus ions were implanted in ZnO single crystals with energies of 50-380 keV having total doses of 4.2ϫ 10 13 -4.2ϫ 10 15 cm −2 . Positron annihilation measurements reveal the introduction of vacancy clusters after implantation. These vacancy clusters grow to a larger size after annealing at a temperature of 600°C. Upon further annealing up to a temperature of 1100°C, the vacancy clusters gradually disappear. Raman-scattering measurements reveal the enhancement of the phonon mode at approximately 575 cm −1 after P + implantation, which is induced by the production of oxygen vacancies ͑V O ͒. These oxygen vacancies are annealed out up to a temperature of 700°C accompanying the agglomeration of vacancy clusters. The light emissions of ZnO are suppressed after implantation. This is due to the competing nonradiative recombination centers introduced by implantation. The recovery of the light emission occurs at temperatures above 600°C. The vacancy-type defects detected by positrons might be part of the nonradiative recombination centers. The Hall measurement indicates an n-type conductivity for the P + -implanted ZnO layer, suggesting that phosphorus is an amphoteric dopant.

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Section: Introductionmentioning

confidence: 99%

Production and recovery of defects in phosphorus-implanted ZnO

Chen

Kawasuso

et al. 2004

Journal of Applied Physics

132

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“…In addition, ion implantation is also actively being explored for TM doping of ZnO [1,12,13,19]. With respect to implantation, the questions that should be clarified, are: to what extent are TMs incorporated into the proper lattice sites (substituting for Zn atoms), what is the microstructure of substitutional TMs, and what are the optimum annealing conditions.We have partly addressed some of these issues in a previous study on Fe-implanted ZnO [20], which, however, focused on its optical properties. In that case, 56 Fe was implanted at 100 keV up to a fluence of 10 16 cm −2 into ZnO single crystals, followed by Rutherford backscattering spectroscopy (RBS) analysis of the damage and its recovery during thermal annealing.…”

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confidence: 99%

“…We have partly addressed some of these issues in a previous study on Fe-implanted ZnO [20], which, however, focused on its optical properties. In that case, 56 Fe was implanted at 100 keV up to a fluence of 10 16 cm −2 into ZnO single crystals, followed by Rutherford backscattering spectroscopy (RBS) analysis of the damage and its recovery during thermal annealing.…”

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Lattice location and thermal stability of implanted Fe in ZnO

Rita

Wahl

Correia

et al. 2004

Applied Physics Letters

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The emission channeling technique was applied to evaluate the lattice location of implanted 59 Fe in singlecrystalline ZnO. The angular distribution of β − particles emitted by 59 Fe was monitored with a position-sensitive electron detector, following 60-keV low dose (2.0×10 13 cm −2 ) room-temperature implantation of the precursor isotope 59 Numerous technological breakthroughs are envisaged with the use of magnetic semiconductor materials that show a ferromagnetic ordering temperature at or above room temperature, e.g., spin transistors, ultradense nonvolatile memories and optical emitters with polarized output [1]. One class of materials, which are especially promising for applications, are diluted magnetic semiconductors, usually ternary systems of the type III 1-x -TM x -V or II 1-x -TM x -VI, where a 3d transition metal (TM) partly substitutes up to a few per cent of the group III or group II cations. It has been predicted by theory that the III-nitride semiconductors GaN and InN and the II-oxide semiconductor ZnO are suitable hosts to exhibit ferromagnetism close to or above room temperature [2,3]. In the case of ZnO, besides V, Cr, Mn, Co and Ni, Fe should also act as a ferromagnetic dopant [3][4][5]. Several reports on ferromagnetic systems based on ZnO can be found in the literature [1,[6][7][8][9][10][11][12][13][14]. Cases in which no ferromagnetic behavior was observed [7,[15][16][17][18] revealed systematic trends for the various transition metals, doping concentrations, and differences between n-and p-type ZnO, but also conflicting results between different authors. It was thus argued [11,14] that experimental reproducibility needs to be improved. The exact nature of the ferromagnetism also remains unclear [1,8,11,13]; among possible problems are the formation of metallic TM or TM-oxide clusters [9,[12][13][14]17] or magnetism from the substrate on which thin films are deposited [18]. Two recent review papers on the subject concluded that a more precise control of the TM dopant in the oxide and careful structural and microstructural analyses are needed [1,11].Experimentally TM dopants have been introduced both during ZnO powder synthesis [10,14,16] and growth of epitaxial thin films [6][7][8][9]11,15,18]. In addition, ion implantation is also actively being explored for TM doping of ZnO [1,12,13,19]. With respect to implantation, the questions that should be clarified, are: to what extent are TMs incorporated into the proper lattice sites (substituting for Zn atoms), what is the microstructure of substitutional TMs, and what are the optimum annealing conditions.We have partly addressed some of these issues in a previous study on Fe-implanted ZnO [20], which, however, focused on its optical properties. In that case, 56 Fe was implanted at 100 keV up to a fluence of 10 16 cm −2 into ZnO single crystals, followed by Rutherford backscattering spectroscopy (RBS) analysis of the damage and its recovery during thermal annealing. Since Fe in ZnO cannot be detected by RBS, particle-induced X-ray emiss...

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“…[1][2][3][4][5][6][7][8] At low temperatures the ultraviolet luminescence is dominated by the recombination processes of donor bound excitons, two electron satellites and LO phonon replicas as well as donor acceptor pairs. 1-8 Even having a rather wide distribution of electronic states within the band gap, as pointed out by photoluminescence ͑PL͒ excitation measurements, 8,9 when excited with photons with lower energy than the band gap, these as-grown samples do not show ultraviolet up-converted luminescence. Similar conclusions can be drawn when ZnO is intentionally doped with Er despite the observed intraionic Er 3+ emission.…”

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Up conversion from visible to ultraviolet in bulk ZnO implanted with Tm ions

Monteiro

Neves

Soares

et al. 2005

Applied Physics Letters

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We report on the up-converted ultraviolet near-band edge emission of bulk ZnO generated by visible and ultraviolet photons with energies below the band gap. This up-converted photoluminescence was observed in samples intentionally doped with Tm ions, suggesting that the energy levels introduced by the rare earth ion in the ZnO band gap are responsible for this process. © 2005 American Institute of Physics. ͓DOI: 10.1063/1.2128491͔ZnO with a high energy band gap, 3.37 eV at room temperature, has been in the last few years one of the most studied materials. The main driving force for research in this oxide semiconductor is the potentialities of ZnO for optoelectronic and spintronic applications.Nominally undoped ZnO samples grown by seeded chemical vapor transport show a highly structured near-band edge emission with above band gap excitation. [1][2][3][4][5][6][7][8] At low temperatures the ultraviolet luminescence is dominated by the recombination processes of donor bound excitons, two electron satellites and LO phonon replicas as well as donor acceptor pairs. [1][2][3][4][5][6][7][8] Even having a rather wide distribution of electronic states within the band gap, as pointed out by photoluminescence ͑PL͒ excitation measurements, 8,9 when excited with photons with lower energy than the band gap, these as-grown samples do not show ultraviolet up-converted luminescence. Similar conclusions can be drawn when ZnO is intentionally doped with Er despite the observed intraionic Er 3+ emission.On the contrary, in all the studied ZnO samples intentionally doped with Tm ions, for which the intra-4f emission is present, we observed ultraviolet recombination when the samples were excited with visible radiation.The samples used in these studies were implanted at room temperature with 150 keV Tm + ions with a nominal fluence of 5 ϫ 10 15 Tm + /cm 2 and subsequently air annealed for 30 min at 800, 900, and 950°C. The implantation damage and annealing effects were investigated with Rutherford backscattering/channeling spectroscopy. We observed that following implantation the majority of Tm ions are incorporated into Zn sites. 10 The optical properties of as-implanted and annealed samples have been studied by photoluminescence ͑PL͒ measurements 10-12 carried out with a 325 nm continuous wave He-Cd laser and an excitation power density typically less than 0.6 W cm −2 . In-gap excitation was accomplished with the 457.9, 476.5, and 514.5 nm argon laser lines. The PL was measured at 7 K using a closed cycle helium cryostat and collected in 90°geometry. The luminescence was dispersed by a Spex 1704 monocromator and detected by a cooled Hamamatsu R928 photomultiplier. With above band gap photoexcitation the ZnO samples intentionally doped with Tm + ions exhibit multi Tm-related optical centers, for which the dominant intraionic emission occurs near 1.56 eV and can be assigned to the 3 H 4 → 3 H 6 transition. [10][11][12] Figure 1 shows typical high energy spectra of as-grown and Tm doped ZnO samples obtained with above ͓͑a͒ and ͑b͔͒ an...

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Photoluminescence and damage recovery studies in Fe-implanted ZnO single crystals

Cited by 58 publications

References 32 publications

Production and recovery of defects in phosphorus-implanted ZnO

Production and recovery of defects in phosphorus-implanted ZnO

Lattice location and thermal stability of implanted Fe in ZnO

Up conversion from visible to ultraviolet in bulk ZnO implanted with Tm ions

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