Effect of varying thermal annealing temperatures on the surface and electrical properties of Mg-doped GaN

Gallium nitride (GaN)-based light emitting diodes (LEDs) have been widely used to produce blue light that, with phosphor, is converted into white light for every-day applications. Despite its high efficiency, the performance of GaN based LEDs is limited by the low electrical conductivity of magnesium (Mg)-doped GaN due to the high activation energy of Mg (140 - 200 meV) as well as the presence of magnesium-hydride (Mg-H) complex, which may passivate Mg as an acceptor. In this study, the efficacy of thermal annealing treatment at temperatures in the range of 550 - 850°C was investigated to activate metal-organic chemical vapor deposition (MOCVD) grown Mg-doped GaN. Changes in the roughness and surface morphology was observed between the varied annealing temperatures by atomic force microscopy (AFM) while X-ray diffraction (XRD) data acts as supporting information for structural quality. Hall effect characterization was conducted to determine electrical properties of the annealed samples. In this study, a correlation between the resistivity and surface roughness trends was observed through the acquisition of an insight into the lattice distortion affecting the material conductivity that occurred specifically at temperatures above 750 °C.