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© 1996 - Elsevier Science S.A.. International Workshop on Beam Injection Assessment of Defects in Semiconductors (BIADS 96) (4. 1996. El Escorial, España). A. Cremades thanks the Universidad Complutense for a predoctoral grant. This work has been partially supported by DGICYT Projects No. HP95-98B and PB93- 1256., GaN epitaxial layers have been investigated by cathodoluminescence (CL) in the scanning electron microscope (SEM). The most prominent feature of the spectra is a complex band at 2.2 eV, whose evolution with temperature and excitation density suggests emission mechanisms involving a deep center and donor-donor or donor-acceptor pairs. Time resolved photoluminescence (TRPL) measurements confirm the involvement of a deep center in the emission. CL images reveal that the centers responsible for this emission decorate grain boundaries. Emission bands al 2.87 eV and 1.31 eV have been also detected in the films., DGICYT (Spain), Universidad Complutense, Depto. de Física de Materiales, Fac. de Ciencias Físicas, TRUE, pub

Several growth methods were employed to investigate the photovoltaic behavior of GaN/Cu[subscript 2]O heterojunctions by depositing cuprous oxide thin films on top of gallium nitride templates. The templates consist of a thin layer of GaN:Si grown on a sapphire substrate by metal organic vapor deposition. The deposition procedure was followed up by photolithographic structuring and thermal evaporation of metal contacts. For device characterization, J-V characteristics and external quantum efficiency were measured, pointing to a possible energy barrier in the conduction band. To gain further insight X-ray photoelectron spectroscopy was applied.