Cathodoluminescence of copper‐doped GaAs and its relation to EL2 centres

Several series of GaAs:Cu crystals are studied with respect to cathodoluminescence properties at cryotemperatures, together with undoped or Si‐doped blank specimens for comparison. A one‐electron model is proposed which comprises the various emission processes related to copper centres in this host material. The presence of EL2 defects in the samples is proved and their energy levels are included in the model. The tendency of Cu and EL2 centres to form complexes is considered. Especially the level hitherto named Cu B is now related to an EL2 defect plus a neighbouring copper ion. The 1.0 eV emission of GaAs:Cu thus becomes comprehensible as electron capture at an arsenic antisite defect associated with substitutional copper.