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HL: Fachverband Halbleiterphysik

HL 85: Poster Session II

HL 85.113: Poster

Thursday, March 17, 2011, 18:00–21:00, P4

Investigation of the local electronic structure of Cu-doped GaN by XANES and XLD — •Ralf Schuber¹, Philipp R. Ganz¹, Fabrice Wilhelm², Andrei Rogalev², and Daniel M. Schaadt¹ — ¹Institute of Applied Physics/DFG-Center for Functional Nanostructures, Karlsruhe Institute of Technology, Germany — ²European Synchrotron Radiation Facility (ESRF), Grenoble, France

Cu doped GaN has been reported to exhibit ferromagnetic behavior at room temperature, in implanted films, nanowires and in grown films. However, there are yet many unanswered questions concerning the mechanism of ferromagnetism in this system. Above all, a detailed understanding of the incorporation of Cu in the GaN host is desirable. The local electronic structure of Cu-doped GaN can suitably be probed by the element specific x-ray linear dichroism (XLD) as well as the x-ray absorption near edge structure (XANES) at the K-edges of Cu and Ga. This was done at the ESRF ID12 beamline on a series of GaN:Cu samples grown by plasma assisted MBE with nominal Cu concentrations between 0% and 2.3%. To clarify the role of the surface compounds on the samples and to evaluate the Cu site position in the GaN host, i.e. Cu on Ga sites, N sites or interstitial sites, we performed simulations of the GaN:Cu and the Cu9Ga4 crystals for the Cu and Ga K-edges at different doping levels using the FDMNES code [1]. A comparison with the experimental results shows that the Cu atoms predominantly occupy Ga and interstitial sites. [1] Y. Joly, Phys. Rev. B, 63, 125120 (2001).