Surface diffusion and layer morphology of (11(2)over-bar2) GaN grown by metal-organic vapor phase epitaxy

(11 (2) over bar2) GaN layers were grown by metal-organic vapor phase epitaxy on (11 (2) over bar2) bulk GaN substrates and (10 (1) over bar0) sapphire substrates. The growth temperature was varied between 950 and 1050 degrees C and the total reactor pressure between 50 and 600 mbar. The growth conditions show a strong impact on the yellow band luminescence properties, while weak impact on the threading dislocation density was observed. The layer morphologies exhibit undulations with two periods along GaN [1 (1) over bar 00] and one period along [11 (2) over bar(3) over bar]. The different period lengths are connected to anisotropic adatom surface diffusion lengths. Arrow like features on the surface originate from the interference of the undulations along [11 (2) over bar(3) over bar] and [1 (1) over bar 00]. (C) 2012 American Institute of Physics. [doi:10.1063/1.3682513]