One possibility of obtaining bulk GaN: Halide VPE growth at 1000 degrees Con GaAs (111) substrates

Halide vapor phase epitaxy (HVPE) is the most promising method for obtainin g bulk GaN, and a 2 inch free standing wafer has been already obtained by g rowing on a sapphire substrate and separating by laser irradiation. It is, however, neither very easy nor very productive. Here we propose another mor e productive way of growing on GaAs substrate, though a free standing GaN i s not yet perfectly obtained. It was found that hexagonal GaN with a smooth surface can be grows on GaAs (111) substrates at as high as 1000 degrees C by introducing GaN layer grown at an intermediate temperature such as 850 degrees C. Surface of the GaN layer grown at 850 degrees C was rough but it became smooth surface when GaN was grown on it at 1000 degrees C, though s ometimes there were several hexagonal pits on the surface. The theta-2 thet a and omega X ray diffraction (XRD) of the grown layer showed only hexagona l GaN(0002).