A study was made of the magnetic properties of 2MeV 4He+-irradiated GaN grown by metal-organic chemical-vapour deposition. Particle irradiation permitted the controllable introduction of Ga-vacancy into the samples. The magnetic moments with concentrations changing between 4.3 and 8.3 x 1017/cm3 revealed super-paramagnetic blocking at room temperature. The appearance of a clear hysteresis curve at T = 5K with a coercive field of about HC ≈ 270Oe suggested that the formation of more complex Ga vacancy related defects was promoted with increasing Ga vacancy content. The small concentration of the observed magnetically active defects with respect to the total Ga-vacancy concentration suggested that the presence of the oxygen/hydrogen-related vacancy complexes was the source of the observed magnetic moments.

Magnetically Active Vacancy Related Defects in Irradiated GaN Layers. L.Kilanski, F.Tuomisto, R.Szymczak, R.Kruszka: Applied Physics Letters, 2012, 101[7], 072102