The growth of green LEDs with InxGa1-xN:Mg p-type layers was studied by employing various epitaxial structures and substrates to control the surface morphology, especially in terms of the formation of pits. The pit densities of the green LED structures grown on sapphire substrates with p-type layers composed of a p-In0.04Ga0.96N:Mg and a graded p-InxGa1-xN:Mg are similar to 1 x 10(9) and similar to 3 x 10(8) cm(-2), respectively. p-type layers composed of p-InGaN:Mg/p-GaN:Mg short-period superlattices are effective in preventing the formation of V-defect related pits. The pit density of green LED structures grown on free-standing GaN substrates with a p-In0.04Ga0.96N:Mg layer is similar to 1.4 x 10(7) cm(-2), which can be correlated to the threading dislocation density in the substrates. (c) 2008 Elsevier B.V. All rights reserved.