Structural And Optical Characterization Of Thick Gan Films Grown By Direct Reaction Of Ga And Nh3

GaN films were grown on (0001) sapphire substrates by a direct reaction of gaseous gallium and ammonia. The GaN films were grown primary along [0002] direction. But the growth of (10 (1) over bar0) and (10 (1) over bar1) planes, which formed the hexagonal pyramids, was included in the films at higher temperature of 1170 degreesC. At a lower temperature of 1170 degreesC, the films included the (10 (1) over bar1) plane which produced the inclined V shaved surfaces. The GaN growth rate increased with the growth temperature, but drastically decreased at high temperature of 1270 degreesC because of the thermal decomposition of GaN. Crystal quality of GaN improved with increasing the NH3 flow rate. The yellow luminescence (YL) was correlated with the (100) peak of the X-ray diffraction (XRD) patterns.