Composition and interface analysis of InGaN/GaN multiquantum-wells on GaN substrates using atom probe tomography

Abstract

In0.20Ga0.80N/GaN multiquantum wells (MQWs) grown on [0001]-oriented GaN substrates with and without an InGaN buffer layer were characterized using three-dimensional atom probe tomography. In all samples, the upper interfaces of the QWs were slightly more diffuse than the lower interfaces. The buffer layers did not affect the roughness of the interfaces within the quantum well structure, a result attributed to planarization of the surface of the first GaN barrier layer, which had an average root-mean-square roughness of 0.18 nm. The In and Ga distributions within the MQWs followed the expected distributions for a random alloy with no indications of In clustering. High resolution Rutherford backscattering characterizations showed the ability to resolve the MQWs, and the resulting compositions and widths corroborated those determined from the atom probe analyses.