AVS 49th International Symposium
    Magnetic Interfaces and Nanostructures Tuesday Sessions
       Session MI-TuP

Paper MI-TuP10
Transition Metal Ion-implanted GaN and Its Magnetic and Structural Properties@footnote *@

Tuesday, November 5, 2002, 5:30 pm, Room Exhibit Hall B2

Session: Aspects of Magnetism
Presenter: Y.D. Park, Seoul National University, Korea
Authors: J.S. Lee, Seoul National University, Korea
Z.G. Khim, Seoul National University, Korea
Y.D. Park, Seoul National University, Korea
S.N.G. Chu, Agere Systems
G.T. Thaler, University of Florida
M.E. Overberg, University of Florida
C.R. Abernathy, University of Florida
S.J. Pearton, University of Florida
Correspondent: Click to Email
We report on the magnetic and structural properties of Co, Cr, and V ion-implanted epitaxial GaN films on sapphire substrates. Dilute magnetic semiconductors (DMS) with ferromagnetic ordering near or above room temperatures have been reported in Mn doped GaN@footnote 1@ and Co doped TiO2,@footnote 2@ subsequent to predictions from a near-field model for GaN doped with a relatively high concentration of Mn.@footnote 3@ Theoretical treatment of ferromagnetic ordering in DMS systems have progressed to include low carrier density regimes@footnote 4@ and incorporation of other magnetic impurities.@footnote 5@ We have found from SQUID magnetization measurements that (Ga,Co)N and (Ga,Cr)N show ferromagnetic ordering below ~ 78 K and ~ 51 K respectively, while (Ga,V)N shows paramagnetic behavior. Structurally from TEM and Selective Area Diffraction Pattern (SADP) data, we have observed that the ion-implantation and subsequent annealing process leaves the expected residual damage in the form of dislocation loops, but no detectable second phases, which corresponds well with the observed modest coercive fields (~100 Oe for (Ga,Co)N) of the samples. By sharp contrast, the presence of ferromagnetic metallic clusters at dimensions below our detection limits would have expected coercivities in the range of thousands of Oersteds. @FootnoteText@ @footnote *@ This work is partially supported by SNU Research Foundation, KOSEF, and Samsung Electronics Endowment through CSCMR. @footnote 1@ M.K. Reed et al., Appl. Phys. Lett. 79, 3473 (2001); S. Sonoda et al., J. Cryst. Growth (in press).@footnote 2@ Y. Matsumoto et al., Science 291, 854 (2001); S.A. Chambers et al., Appl. Phys. Lett. 79, 3467 (2001)@footnote 3@ T. Dietl, H. Ohno, F. Matsukura, J. Cibert and D. Ferrand, Science 287, 1019 (2000).@footnote 4@ R.N. Bhatt et al., J. Supercon. 15, 71 (2002).@footnote 5@ K. Sato and H. Katayama-Yoshida, Jap. J. Appl. Phys. 40, L485 (2001); H. Katayama-Yoshida et al., J. Cryst. Growth 231, 438 (2001).