Browsing by Author "Photongkam, P"

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    Development of advanced diluted magnetic semiconductors with rare earth doping technology
    (University of Western Australia, 2007-10-15) Photongkam, P; Ionescu, M; Zeng, R; Yu, DH; Li, S
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    Doping of ZnO thin film with Eu using ion beams
    (Trans Tech Publications, 2010-01-01) Ionescu, M; Photongkam, P; Yu, DH; Siegele, R; Li, S; Cohen, DD
    Modification of electric and magnetic properties of ZnO thin films was achieved by low energy Eu ion irradiation. The desired doping levels as well as the depth distribution of the dopant was controlled by the ion energy and the ion flux, following a simulated interaction between the doping ion and the host ZnO matrix of epitaxial ZnO (0001) films of approximatelly 200nm, grown on c-Al2O3 by PLD. The properties of the doped ZnO film depend in a critical way on the homogeneity of the doped ions throughout the entire film. The doping levels and the depth distribution of dopants were measured by elastic recoil detection analysis (ERDA). The results show a uniform depth distribution of Eu, as well as some level of Al diffusion from the substrate and the presence of some low levels of H, N and O. PACS code: 68.49Sf; 74.78Bz.
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    Enhancement of co substitution induced by Eu codoping in ZnO-based diluted magnetic semiconducting thin films
    (American Institute of Physics, 2010-02) Photongkam, P; Zhang, YB; Assadi, MHN; Li, S; Yu, DH; Ionescu, M; Pan, AV
    To avoid the occurrence of doped magnetic ion clustering is a challenge in fabrication of diluted magnetic semiconductors (DMSs). In this work, we report the intrinsic ferromagnetic behavior in Co-doped ZnO DMSs induced by Eu codoping. Both structural parameters and magnetic properties demonstrate the existence of an interaction between Co and Eu ions. The observation of multiplet structures for the localized Co 3d states in x-ray absorption and x-ray magnetic circular dichroism characterization evidences that the codoped Eu plays an important role in facilitating the Co substitution of Zn, leading to intrinsic ferromagnetism. © 2010, American Institute of Physics
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    Fabrication and characterisation of diluted magnetic semiconductors thin films using ion beams
    (Trans Tech Publication Inc., 2012-01-01) Ionescu, M; Photongkam, P; Siegele, R; Deslandes, A; Li, S; Cohen, DD
    The intrinsic n-type (II-VI) semiconductor ZnO may become ferromagnetic at room temperature, by small additions of magnetic ions, resulting in what is called a Diluted Magnetic Semiconductors (DMS). The potential application of DMS in spintronic devices of is driving the research effort to dope magnetic elements into this semiconductors with a depth distribution as uniform as possible. The doping levels and the depth distribution of dopants are critical parameters for the magnetic properties of this material and the possible clustering of dopants can play a significant negative role in its macroscopic magnetic properties. Thin ZnO (0001) films of between 100nm and 500nm, grown on c-Al2O3 by MOCVD were implanted with Co, Eu and Co+Eu by ion irradiation at low energies. In order to improve the depth distribution of dopants, the ion implantation was carried out through a number of appropriately chosen range foils. The results show an increase in the level of dopant homogeneity throughout the entire thickness of the film, and a ferromagnetic behavior above room temperature for Zn0.96Co0.04O, Zn0.96Eu0.04O and Zn0.92Co0.04Eu0.04O. © 2012, Trans Tech Publications