Surface morphology control of green LEDs with p-InGaN layers grown by metalorganic chemical vapor deposition

Abstract

The growth of green LEDs with In x Ga 1− x N: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-In 0.04Ga 0.96N:Mg and a graded p-In x Ga 1− x N:Mg are ∼1×10 9 and ∼3×10 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-In 0.04Ga 0.96N:Mg layer is ∼1.4×10 7 cm −2, which can be correlated to the threading dislocation density in the substrates.