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 cente rs in GaAs, we grew Er-doped GaAs by low-pressure metalorganic chemica l 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 line s and bands. The spectrum of a sample grown in a hydrogen atmosphere c ontaining 0.2 ppm oxygen, on the other hand, was simple and had few li nes. The spectrum of the oxygen-codoped sample showed higher peak inte nsities as well as higher integrated luminescence intensity in the 1.5 -1.6 mum region. Secondary-ion mass spectroscopy revealed that the oxy gen-codoped sample had a higher concentration of oxygen, indicating th e formation of an Er-O complex center. One kind of optically active ef ficient Er-O complex luminescence center can, therefore, be selectivel y formed under suitable MOCVD growth conditions.