Polarity related problems in growth of GaN homoepitaxial layers

Homoepitaxial layers of GaN were grown by metalorganic chemical vapour deposition on single crystals obtained by high-pressure, high-temperature technology. For each metalorganic chemical vapour deposition run, four samples were placed, (00.1) and (00.1') faces of the Mg-doped insulating and undoped highly-conductive substrates. The layers were examined using X-ray diffraction, photoluminescence and far infrared reflectivity. It was found that the (00.1') easier incorporates donors resulting in higher free electron concentrations in the layers grown on these sides of the crystals, both undoped and Mg-doped. (author)