Two-photon photoluminescence and current images of bulk GaN and InGaN green LEDs

Our recent studies shows that GaN possesses large two-photon absorption coefficients, even at infrared (IR) wavelength dose to midgap energy. This indicates that two photon confocal photoluminescence images and two-photon optical-beam-induced-current (TP-OBIC) microscopy can be applied on the GaN studies and imaging. Confocal laser scanning microscopy provides a significant improvement in axial resolution over conventional epi-fluorescence microscopy by eliminating out-of-focus fluorescence using a spatial filter in the form of a confocal aperture.