Effect of carbon doping on GaN:Er

The effect of carbon doping on the photoluminescence (PL) and morphology of GaN:Er has been investigated. GaN:Er,C with [Er] similar to 8.5 x 10(20) cm(-3), was grown using elemental Ga, elemental Er and CBr4 via gas-source molecular beam epitaxy (GSMBE). The optimum room temperature 1.54 mum PL intensity was obtained for a carbon concentration of similar to 7.7 x 10(20) cm(-3). Further increase in the carbon concentration led to a decrease in overall PL intensity, but slightly decreased the degree of thermal quenching between 20 and 300 K. Comparison of thermal quenching data of GaN:Er grown with triethylgallium (TEG) and that grown with elemental Ga suggests that oxygen is more effective than carbon at suppressing thermal quenching. Material grown without high impurity backgrounds shows 75% quenching while that grown with TEG shows no quenching. Carbon-doped material falls in between these two values depending upon the amount of carbon in the film. Annealing improved the 300 K PL intensity from carbon-doped material and decreased the intensity from low impurity material. (C) 2001 Elsevier Science B.V. All rights reserved.