Study of high-quality GaN grown by OMVPE using an intermediate layer

The crystalline quality of heteroepitaxial GaN can be significantly improved if the threading dislocations originating from the interface are not allowed to reach the layer surface where they can propagate to the active device areas and act as harmful defects. Incorporation of an intermediate layer grown at low temperature has been shown to limit this defect propagation. This method has been proved to be effective but several interlayers have been required in order to reach dislocation density lower than 10(9)/cm(2). In this priority communication, we report on high-quality GaN layers grown with the use of only one intermediate layer. The defect analysis shows that the density of dislocation is only 8 x 10(7)/cm(2), compared to over 10(10)/cm(2) for layers grown without the intermediate layer. Electron microscopy on cross-section samples shows that deposition under certain low-temperature conditions directly benefits the quality of the subsequently deposited GaN layer. The growth of the GaN top layer appears to be similar to growth observed for lateral epitaxial overgrowth layers. This observation opens the possibility for using standard GaN growth methods to achieve a dislocation density comparable to that achieved with lateral overgrowth epitaxy. Published by Elsevier Science B.V.