InGaN alloys have gained considerable interest over the past due to their tunable band gap extending the operation wavelengths of optoelectronic devices to green–red and IR regions. However, the realization of high In-content InGaN materials is still limited by their material properties. Despite encouraging achievements in InGaN based devices, it is difficult to achieve high quality InGaN with high indium composition. Up to now, there are only few reports about high indium content InGaN films, in particular with indium content > 50%.
Successfully grown In-rich InGaN layers with 300 nm thickness and nominally [In] = 70% deposited on GaN template by MBE were comprehensively investigated by highly spatially-resolved cathodoluminescence. The surface morphology has been investigated by atomic force microscope (AFM) and scanning electron microscopy (SEM) and shows grain-like features. The lateral as well as the vertical luminescence distribution yields a detailed insight in the [In] homogeneity. The thick InGaN films, free of droplets, have a quite homogenous emission at 1.035 eV (~1200 nm) laterally with full-width at half maximum of only 68 meV. Determined from the emission peak, the indium composition is about 75%, which is slightly higher than the nominally intended indium composition. The evolution in growth direction will be presented.