Structural and optical properties of In-rich InGaN nanodots grown by metallo-organic chemical vapor deposition

The surface morphologies, alloy compositions and emission properties of In-rich In_xGa_1-xN nanodots (x≥0.87) grown by metallo-organic chemical vapor deposition at various growth temperatures (550-750°C) were investigated. We found that the nucleation of InGaN dots was dominated by the surface migration of In adatoms. A higher Ga content can be achieved at lower growth temperatures due to the relatively lower migration ability of Ga adatoms. At higher growth temperatures, the InGaN dots tend to decompose into In-rich islands and a thin Ga-rich layer. These In-rich islands exhibit photoluminescence emission in the near-infrared range. Another visible emission band was also observed for samples grown at higher temperatures. The formation of a thin Ga-rich layer is likely to be responsible for the visible emission.