Abstract
Hydrogen plays an important role in GaN and related alloys. It is often a part of the growth environment and can be incorporated in GaN during different processing steps. Its behaviour is rather complicated and poorly understood. GaN doped with Fe has currently gained an increasing interest as a suitable magnetic semiconductor for spintronic applications. Here, we report results of the study on GaN doped with Fe and codoped with Mg for deep acceptors, Si for shallow donors and isoelectronic Al. Samples were grown by the chemical transport process in the form of small (∼0.3
mm) crystallites and subsequently pressed to form platelets. As-grown samples and after annealing in different atmospheres (successively with N
2 and NH
3) were studied. Hydrogen concentrations were determined by NRA using the
15N profiling method. Hydrogen release due to the analysing beam was evaluated using the molecular recombination model. Effective H-release cross section was found to be the same for all GaFeN samples, independent of codoping. The lowest concentration of hydrogen among as-grown materials was revealed in GaFeN samples. Codoped materials showed higher hydrogen concentration, increasing in the following sequence: Mg, Si and Al. Hydrogen concentration can be substantially reduced by annealing in N
2 atmosphere, whereas subsequent annealing in NH
3 produces hydrogenation, however, to concentrations below that for pristine samples. The model of these processes has been proposed.