摘要
Investigating closely stacked GaN/AlN multiple quantum wells(MQWs)by means of cathodoluminescence spectroscopy directly performed in a scanning transmission electron microscope,we have reached an ultimate spatial resolution ofσCL=1.8 nm.The pseudomorphically grown MQWs with high interface quality emit in the deep ultraviolet spectral range.Demonstrating the capability of resolving the 10.8 nm separated,ultra-thin quantum wells,a cathodoluminescence profile was taken across individual ones.Applying a diffusion model of excitons generated by a Gaussian-broadened electron probe,the spatial resolution of cathodoluminescence down to the free exciton Bohr radius scale has been determined.
基金
National Key Research and Development Program of China(2017YFE0100300)
Science Challenge Project(TZ2016003)
National Natural Science Foundation of China(61734001,61521004,61774004)
Deutsche Forschungsgemeinschaft(Research Instrumentation Program INST272/148-1,Collaborative Research Center SFB 787)。
