Preferential substitution of Fe on physically equivalent Ga sites in GaN

✍ Scribed by W. Gehlhoff; D. Azamat; U. Haboeck; A. Hoffmann

• Publisher: Elsevier Science
• Year: 2006
• Tongue: English
• Weight: 228 KB
• Volume: 376-377
• Category: Article
• ISSN: 0921-4526
• DOI: 10.1016/j.physb.2005.12.124

✦ Synopsis

The EPR spectra of Fe 3þ in high-quality thick freestanding hydride vapor phase grown GaN have been studied in the X-and Q-band. A complex resonance pattern with numerous lines of different intensities provided by three different defects is observed for these nearly stress-free iron-doped samples. The dominating part is due to isolated Fe 3þ on Ga sites and can be well described with a spin Hamiltonian (SH) with S ¼ 5 2 considering the two magnetically inequivalent Ga sites with C 3v symmetry in the wurtzite structure of GaN. Aside from the displacement of their magnetic axis the two Ga sites are physically equivalent. However, contrary to the expectation, we observed different Fe populations of both sites that varied from a ratio 1:4 to a ratio of nearly 1:1 in different crystals. In addition and in contrast to previously published data we determined nearly isotropic g-values and larger values for the axial fine-structure parameters D, a-F and much larger value for the cubic fine-structure parameter a.