Cathodoluminescence imaging and spectroscopy by near-field detection

Using near-field techniques, we have developed an experimental set-up for spatially resolved cathodoluminescence (CL) spectroscopy and monochromatic imaging. It combines a scanning near-field optical/force microscope with a scanning electron microscope equipped with a field emission gun. The potentialities of this scanning near-field cathodoluminescence microscope are demonstrated on two kinds of sample: an indented MgO crystal and AlGaN/GaN quantum wells grown on GaN/sapphire. Monochromatic CL imaging allows a clear distinction between the emission of quantum wells and the GaN substrate, and for the MgO crystal, the localization on the slip bands, near the indentation, of luminescent centres emitting at 450 nm.