Defects in Ga(In)NAs thin films grown by atomic H-assisted molecular beam epitaxy

摘要

The vacancy-type defects in Ga_(1-y)In_yN_xAs_(1-x) dilute nitride films grown by atomic H-assisted molecular beam epitaxy (H-MBE) were investigated. The positron annihilation measurements showed that the densities of vacancy-type defects in GaN_xAs_(1-x) (x=0%-1.3%) films grown under an optimized atomic H flux were as low as that for a liquid encapsulated Czochralski (LEC) GaAs substrate. Further, the influence of vacancy-type defects on the crystal quality and optical properties were studied by x-ray diffraction and photoluminescence (PL) measurements. The integrated PL intensity at 77 K drastically decreased as N composition was increased, but we found no clear correlation between the density or volume of vacancy defects and optical properties, and the S parameters were nearly constant at a value of ～0.516 in all Ga_(1-y)In_yN_xAs_(1-x) films grown by our H-MBE technique.