The effect of substrate misorientation on the photoluminescence properties of GaN grown on sapphire by metalorganic chemical vapor deposition

We report the growth and photoluminescence (300 and 4.2 K) characterization of unintentionally doped GaN on both exact and vicinal (0001) sapphire substrates. The GaN heteroepitaxial layers are grown by metalorganic chemical vapor deposition on sapphire substrates using various growth conditions. The (0001) Al2O3 c-plane substrates are oriented exactly (0001) or misoriented either 2 degrees towards the a plane (<11(2)over bar 0>), 5 degrees towards the m plane (<10(1)over bar 0>), or 9 degrees toward the m plane. A comparison of the 300 and 4.2 K optical characteristics of the samples grown on the different substrates indicates that a higher photoluminesence intensity is measured for the films on misoriented substrates. (C) 1996 American Institute of Physics.