Temperature Induced Microstructural Changes in InGaN/GaN Quantum Wells Observed by Electron Microscopy

Author(s): Alexandra Gkanatsiou, Christos B Lioutas, Ewa Grzanka, Mike Leszczynski

The present work concerns the microstructural characterization of multiple InGaN/GaN Quantum Well (QW) structures grown onto GaN on sapphire templates by Metalorganic Chemical Vapor Phase Epitaxy (MOVPE), using electron microscopy techniques (Transmission Electron Microscopy-TEM and Scanning Electron Microscopy-SEM). The TEM characterization showed V-shaped defects, including V-pits and trench defects on the surface of the as-grown sample. Post-growth annealing experiments were performed in order to determine whether a structural degradation of the structure has taken place. After annealing a very small density of V-defects was observed, having a beneficial impact on optoelectronics performance. The presence of sharp interfaces between the InGaN QWs and the GaN barriers gave us an indication of their good structural quality.