SELECTIVE FORMATION OF AN EFFICIENT ER-O LUMINESCENCE CENTER IN GAAS BY METALORGANIC CHEMICAL-VAPOR-DEPOSITION UNDER AN ATMOSPHERE CONTAINING OXYGEN

To investigate the effects of oxygen codoping on Er luminescence centers in GaAs, we grew Er-doped GaAs by low-pressure metalorganic chemical vapor deposition (MOCVD) and measured the photoluminescence spectrum due to the intra-4f-shell transition of Er. The spectrum of a sample grown in a pure hydrogen atmosphere was complicated, showing many lines and bands. The spectrum of a sample grown in a hydrogen atmosphere containing 0.2 ppm oxygen, on the other hand, was simple and had few lines. The spectrum of the oxygen-codoped sample showed higher peak intensities as well as higher integrated luminescence intensity in the 1.5-1.6 mum region. Secondary-ion mass spectroscopy revealed that the oxygen-codoped sample had a higher concentration of oxygen, indicating the formation of an Er-O complex center. One kind of optically active efficient Er-O complex luminescence center can, therefore, be selectively formed under suitable MOCVD growth conditions.