Deep UV imaging by spectrometric full-colour cathodoluminescence microscopy

Abstract

A new deep-UV cathodoluminescence (CL) microscopy is tried on studying design and fabrication of recent solid-state light-emitting (LE) devices that emit near 200 nm light. CL microscopy has enough energy for electronic excitation of deep-UV emitting devices and visualizes distribution map of their electronic structures. The deep-UV imaging system is constructed on our own spectrometric full-colour CL microscope that collects CL spectra at all pixel points of the specimen during regular SEM observation, and at the end of one frame scan, a set of CL spectra is accumulated in the control computer. One frame scan of 512x512 pixels needs 8 to 80 sec, which is unbeatable by any other commercial CL microscopes. Full-colour CL micrograph is constructed using the spectra. The detector, a 32-channel photoelectron multiplier array, has higher sensitivity in UV region than any solidstate linear sensors, and a grating of 300-nm blaze wavelength instead of one at 500-nm blaze wavelength for visible lights, provide CL micrographs of 180-700 nm lights for recent deep-UV LE devices. Some unforeseen light emissions between 200-350 nm regions are observed on various materials and they are discussed correlating with the structure observed in SEM micrographs.