Cathodoluminescence spectroscopy and imaging of individual GaN dots

Uncapped GaN dots on AlGaN barrier material, grown by metal organic chemical vapor deposition on 6H–SiC substrates, were studied. Cathodoluminescence (CL) microscopy and scanning electron microscopy (SEM) were used to investigate both luminescence and structure of individual GaN dots. The correlation between the luminescence and the actual position of self-assembled dots was demonstrated. The position of a dot was established with high resolution SEM and a CL image was used to display the corresponding luminescence. The spectrum from a single dot was obtained by positioning the electron beam on one particular dot. The luminescence from dots with a lateral size of 100 nm and a height of 40 nm was determined to be 3.47 eV.