Berlin 2008 – scientific programme

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DS: Fachverband Dünne Schichten

DS 27: Trends in Ion Beam Technology: From the Fundamentals to the Application

DS 27.2: Invited Talk

Thursday, February 28, 2008, 15:00–15:30, H 2013

Rare earth doping of GaN — •André Vantomme — Instituut voor Kern- en Stralingsfysica and INPAC, K.U.Leuven, Celestijnenlaan 200 D, B-3001 Leuven, Belgium

Group III-nitrides, e.g. GaN, are suitable hosts for incorporating rare earths (RE), potentially resulting in visible light emission at various wavelengths. Ion implantation is commonly employed for semiconductor doping, presenting several advantages over other techniques, such as in situ doping. However, implantation induces radiation damage to the lattice, which can have detrimental effects on the electrical and optical properties of the material. Further, the exact lattice site of the implanted ions has to be known, since it strongly influences the intensity and splitting of the optical transitions. We have studied the defect accumulation during RE (Er, Eu, Tm) implantation into GaN, as well as the lattice site of the implanted ions, varying a range of experimental parameters such as the implanted fluence, temperature, angle of the beam incidence, energy, annealing conditions The defect concentration and profile were assessed by channelling spectroscopy and high-resolution X-ray diffraction. By emission channelling, the lattice site of implanted radioactive ions was accurately determined, including the root mean square displacement from the ideal sites. From our study, we derived a general model correlating the induced defects, strain and the ion lattice sites, irrespective of the implantation parameters. Finally, these structural properties were linked to the optical and electrical characteristics of the nitride, investigated by photo- and cathodoluminescence and by deep level transient spectroscopy respectively.