Atomic Scale Analysis of InGaN Multi-Quantum Wells

Abstract

ABSTRACTInGaN multiquantum wells grown by MOCVD on GaN have been investigated by transmission electron microscopy techniques and numerical analysis of high resolution (HREM) images. One objective of this research was to correlate the atomic structure and emission mechanisms of InGaN quantum well. The studied layers contained 13% or 20% In. It was shown that GaN/InGaN interfaces are rather rough and exhibit an oscillating contrast. Structural defects were found on these interfaces. The relative c-lattice parameter variation in the well was determined using numerical processing of HREM images. The lattice spacings appear to be larger than that expected from Vegard's law suggesting the presence of a biaxial strain. Further observations also revealed a redistribution of In within the well. Instead of a continous In-rich layer, quantum dots were often observed along the well with a regular spacing. The formation of these In-rich dots was not intented and their presence suggests either a periodic modulation of strain along the well or In-rich cluster formation.