Shallow donors in GaN: A magnetic double resonance investigation

Abstract

The residual shallow donor in GaN is investigated by electron spin resonance and the Overhauser shift double resonance technique. From the resolved quadrupolar splitting, we determine the electric field gradients at the Ga and the N site. The hyperfine interaction, as determined simultaneously from the Overhauser shift and the Knight shift, supports a delocalized donor wavefunction with an effective Bohr radius of 20–30 Å.