液相エピタキシャル法によるGa_1-xAl_xAs厚膜の成長

抄録

Temperature-gradient liquid-phase-epitaxial growth technique for Ga_l-xA1xAs thick layers with almost uniform composition is reported.
In this technique, using a relatively small amount of the Ga solution, the Ga_l-xA1xAs source was prepared by adding excess amounts of GaAs and Al source materials to the Ga solution and by using a temperature-overshoot method. GaAs substrates were made contact with the solutions by a slide method for obtaining identical layers with high reproducibility.
It has been clarified that the composition of the grown layers depends on the amounts of the excess materials, overshoot temperature and growth temperature. Under the optimun condition, 300 to 500μm thick Ga_l-xA1xAs layers with almost uniform composition were grown. Under certain other conditions, layers whose AlAs composition increased along the growth direction were obtained. These thick layers have been used for dome-shaped Ga_l-xA1xAs LEDs, which have a maximum of 53 mW output and 18.3% external quantum efficiency.