CATHODOLUMINESCENCE MICROSCOPY AND SPECTROSCOPY OF SEMICONDUCTORS ANDWIDE BANDGAP INSULATING MATERIALS

Cathodoluminescence (CL) corresponds to the emission of photons observ ed from semiconductors and wide bandgap insulating crystals exposed to an electron bombardment. The radiative de-excitation of the created h ole-electron pairs may occur according to an intrinsic mechanism (dire ct band to band recombination) or may be an extrinsic mechanism involv ing charge recombination through energy levels associated with impurit ies or point defects. For low bandgap materials, local analysis of sem iconductor physical properties such as surface (interface) recombinati on velocity and minority carrier diffusion length are studied by means of CL measurements at different incident electron energies. For wide bandgap insulators the complementarity of CL and X-ray spectrometries is illustrated for the case of the localisation of trace elements and for the case of charging phenomena related to the presence of pre-exis ting point defects and induced defects during the electron bombardment . Examples of CL microscopy and spectroscopy applied to the microchara cterisation of semiconductors (GaAs, InP and related materials) and of synthetic and natural mineral materials (ZnS, SiO2, rare-earth bearin g crystals), are presented.