Correlating compositional, structural and optical properties of InGaN quantum wells by transmission electron microscopy

We use structural and analytical transmission electron microscopy to study the scale on which InGaN alloy fluctuations influence the optical properties of InGaN quantum wells. We show that compositional and layer thickness fluctuations can be present in InGaN thin layers, depending on the growth conditions and In concentrations. Spectrally and spatially resolved cathodoluminescence performed in the transmission electron microscope indicates that the optical properties of InGaN quantum wells depend on short range order on an atomic scale rather than on medium-range clustering due to lateral segregation.