Effects of microwave activation power on the structural properties of sol-gel spin coated magnesium doped gallium nitride thin films

In this paper, the effects of microwave (MW) activation power on the structural properties of sol-gel spin coated magnesium (Mg) doped gallium nitride (GaN) thin films grown on sapphire (001) substrates were reported. The activation processes were carried out using different microwave powers (i.e., 100 W, 200 W, 300 W and 450 W) for a duration of 10 minutes. X-ray diffraction results indicate that the Mg-doped GaN thin films exhibit hexagonal wurtzite structure with (002) preferential orientation. Mg-doped GaN thin film activated at 450 W has the highest dislocation density, delta, implies that it has the largest amount of nitrogen vacancies compared to all the other samples, and consequently the poorest crystalline quality as proved by the drastic decrease in intensities of the XRD peaks of the film. Since nitrogen vacancies are favorably formed only upon the removal of hydrogen from p-type GaN, it can be concluded that the activation process of Mg dopants is most efficient at 450 W. Tensile strain along c-axis of the film activated at 450 W further validates this statement. In summary, 450 W is the best power for the activation process of Mg dopant, but yet it is not the most ideal microwave power because it deteriorates the crystalline quality of the films. (C) 2019 Elsevier Ltd. All rights reserved.