Spin-dependent processes and Mg-acceptors in GaN single quantum well diodes and p-type GaN films

Electrically detected magnetic resonance (EDMR) measurements at 34 GHz were performed to obtain more information about the rate limiting transport processes in blue and green InGaN single quantum well light emitting diodes. With respect to g-factor and linewidth, two centers in both diodes were resolved, which could not be separated in earlier 9 GHz experiments. The position of an enhancing signal at g ≈ 2.008 (ΔB ≈ 15 mT) is found to shift to g ≈ 2.010 with increasing forward bias. Comparative EDMR and EPR (electron paramagnetic resonance) measurements on p-type GaN:Mg and Al_0.3Ga_0.7N:Mg films show that this feature is caused by spin-dependent hopping in the acceptor band of the p-type Al_0.3Ga_0.7N cladding layers in the diodes. In addition, a quenching line at g ≈ 2.002 (ΔB ≈ 18 mT) was observed at high forward biases as well as under reverse breakthrough conditions.