Site selectivity of Fe-Ga(3+) and the formation of Fe-Ga(3+)-Ga-i pairs in GaN

摘要

The electron paramagnetic resonance (EPR) spectra of Fe-related defects in high quality thick freestanding hydride vapor phase (HVPE) grown GaN have been studied in the X- and Q-band. The dominating part of the complex resonance pattern is due to isolated Fe3+(3d(5), S = 5/2) on the two equivalent Ga sites A and B with C,v point symmetry in the hexagonal GaN unit cell. These two physically equivalent sites, caused by the ABAB stacking sequence of the wurtzite structure, can be distinguished by EPR for electron spin systems S >= 2. We found a preferential incorporation of Fe in one of the two types of Ga sites. Moreover, despite the strong overlap with the intensive Fe3+ transitions we could identify the main part of the additional observed very weak lines as Fe-Ga(3+)-Ga-i pairs. (c) 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.