Magnetic resonance investigations of defects in Ga¹⁴N and Ga¹⁵N

The influence of the nitrogen nuclear spin on the optically detected magnetic resonance and electron spin resonance signatures of the intrinsic shallow donor and a deep defect causing the characteristic yellow luminescence have been studied on wurtzite GaN epitaxial layers grown by plasma induced molecular beam epitaxy with isotopically pure ¹⁴N and ¹⁵N. In particular, the linewidth of the deep defect signal is observed to be independent of the nitrogen isotope. The missing effect of the different nuclear spin properties of the ¹⁴N and ¹⁵N isotopes is discussed in view of current microscopic models for the yellow luminescence in GaN.