Formation of metallic In in InGaN∕GaN multiquantum wells

In x Ga 1 − x N ∕ Ga N light-emitting diode structures with a high In concentration may lose all optical output after capping the active region with a p-type GaN layer. Transmission electron microscopy has been applied to determine the microstructural changes that occur in the quantum-well (QW) region during this capping process. The loss of the optical output is related to a clustering of In into metallic In platelets in the QW region. The properties of these In platelets are described and a formation model is proposed.