Rare Earth Doped Zinc Oxide Nanowires

Geburt, Sebastian; Stichtenoth, D.; Müller, Sven; Dewald, W.; Ronning, Carsten; Wang, J.; Jiao, Yan; Rao, Yangyan; Hark, S. K.; Li, Quan

doi:10.1166/jnn.2008.n05

Cited by 34 publications

(35 citation statements)

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“…We show this comparison because it has been reported that, during RE ion implantation into ZnO, the dopant atoms are distributed homogeneously. 28 We find that DE is sufficiently large in favor of FM coupling in Gd-doped ZnO nanowires in the neutral state. A significant DE (as high as 21 meV) is obtained for the nearest neighbor Gd atoms in the neutral state.…”

Section: Resultsmentioning

confidence: 71%

Ferromagnetism in Gd doped ZnO nanowires: A first principles study

Aravindh

Schwingenschloegl

Roqan

2014

Journal of Applied Physics

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Size effects on formation energies and electronic structures of oxygen and zinc vacancies in ZnO nanowires: A first-principles study J. Appl. Phys. 109, 044306 (2011) In several experimental studies, room temperature ferromagnetism in Gd-doped ZnO nanostructures has been achieved. However, the mechanism and the origin of the ferromagnetism remain controversial. We investigate the structural, magnetic, and electronic properties of Zn 48 O 48 nanowires doped with Gd, using density functional theory. Our findings indicate that substitutionally incorporated Gd atoms prefer occupying the surface Zn sites. Moreover, the formation energy increases with the distance between Gd atoms, signifying that no Gd-Gd segregation occurs in the nanowires within the concentration limit of 2%. Gd induces ferromagnetism in ZnO nanowires with magnetic coupling energy up to 21 meV in the neutral state, which increases with additional electron and O vacancy, revealing the role of carriers in magnetic exchange. The potential for achieving room temperature ferromagnetism and high T C in ZnO:Gd nanowires is evident from the large ferromagnetic coupling energy (200 meV

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Section: Resultsmentioning

confidence: 71%

Ferromagnetism in Gd doped ZnO nanowires: A first principles study

Aravindh

Schwingenschloegl

Roqan

2014

Journal of Applied Physics

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“…A fully relaxed device with low initial conductivity of ≈ 0, 5 nA increases its conductivity to 6 nA in distinct steps during ≈ 350 s of exposure. Terbium was used for this implantation to show that the PIC effect is not at all ion specific and because rare earths show interesting optical effects in ZnO [21].…”

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confidence: 99%

Persistent ion beam induced conductivity in zinc oxide nanowires

Johannes

Niepelt

Gnauck

et al. 2011

Applied Physics Letters

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We report persistently increased conduction in ZnO nanowires irradiated by ion beam with various ion energies and species. This effect is shown to be related to the already known persistent photo conduction in ZnO and dubbed persistent ion beam induced conduction. Both effects show similar excitation efficiency, decay rates and chemical sensitivity. Persistent ion beam induced conduction will potentially allow countable (i.e. single dopant) implantation in ZnO nanostructures and other materials showing persistent photo conduction.The one dimensional geometry of nanowires leads to an immense surface to volume ratio and the path of any current through the wire is always close to the surface. Sensing applications [1,2] benefit directly from this pronounced surface influence on electrical characteristics. Metal oxides in general and ZnO thin films in particular have already shown a good ultra-violet (UV) [3] and gas-sensing [4] ability due to the instability of oxygen at the surface [5][6][7]. As the surface influence is increased in nanowires, greatly enhanced sensitivity is expected from nanowire devices [1,6]. Although the conductivity of ZnO can easily be increased by three orders of magnitude by UV excitation, the current only returns to the relaxed value very slowly due to the known Persistant Photo Conduction (PPC) effect [6,[8][9][10].In this work, we report that an analogue Persistant Ion beam induced Conduction (PIC) arises during ion irradiation. PIC may allow single ion detection in individual ZnO nanowires, as well as countable doping with single dopants into ZnO nanowires. The strongly localized energy deposition of a single ion impact can result in a change in the properties of the entire device, providing a localized probe to understand the underlying excitation mechanisms.The typical lifetime of charge carriers in ZnO nanostructures is in the order of 100 ps [11]. To contribute to a persistent current increase, excited charge carriers have to populate distinct, stable states. According to Prades et al. [6] these are surface-oxygen bound states. Further discussion on the origin and properties of PPC can be found in literature [1, 6-10, 12, 13]. For PIC discussed in this work, ions instead of UV photons generate electron hole pairs in the semiconductor. By qualitative comparison we show that PIC and PPC rely on the same mechanism.The ZnO nanowires used for this work were grown via vapor-liquid-solid growth [14][15][16] and have a typical diameter range of 150 to 250 nm. They were imprinted onto the desired substrate by lightly pushing the substrate across the densly covered growth sample. Via photolithography and electron-beam evaporation, Ti/Au 50/50 nm contact pads were defined onto the sparsely * andreas.johannes@uni-jena.de covered substrate. Some wires span the 5 µm space between contact pads (see inset figure 1). Superfluous wires were easily cut with a focused ion beam to reliably manufacture single, contacted nanowires with this randomsuccess method. The nanowire devices were then contacted a...

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“…To grow p ‐type ZnO, the acceptor concentration has to be higher than the unintentional donor concentration. Different authors have reported the effect of doping with V‐group elements such as As, P, N, and effect of doping also with Tm, Yb, and Eu using ion implantation and post annealing was reported in the literature . Recently, also Sb has been proposed as acceptor doping …”

Section: Preparation Techniques and Growth Mechanismsmentioning

confidence: 99%

Metal Oxides Mono‐Dimensional Nanostructures for Gas Sensing and Light Emission

et al. 2012

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The present Review opens with an overview of metal oxides and the description of their material properties. The first part mainly deals with various preparation techniques and growth mechanisms, which have been largely developed in the last few decades to fabricate different types of metal oxide nanostructures. The second part, on the other hand, will provide the Reader with an up-to-date summary of different applications in which metal oxides nanostructures have been successfully implemented and/or suggested. In particular, great attention will be dedicated to the implementation of metal oxide nanostructures for gas sensing as well as light emission applications, for which both working principles and integration, as well as the latest reported cutting edge results are herein reported. Finally, we emphasize on the current potentials of metal oxide nanostructured materials and future challenges that this field in continuous expansion is currently facing

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Rare Earth Doped Zinc Oxide Nanowires

Cited by 34 publications

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Ferromagnetism in Gd doped ZnO nanowires: A first principles study

Ferromagnetism in Gd doped ZnO nanowires: A first principles study

Persistent ion beam induced conductivity in zinc oxide nanowires

Metal Oxides Mono‐Dimensional Nanostructures for Gas Sensing and Light Emission

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