Nature and origin of dark defects in GaAs LED's

Dark defects of GaAs LED's diffused with Zn through coated SiO
2
films are observed in EBIC images as well as in EL images. The results of etch-pit observations have shown that some dislocations involved in the initial crystal are pinned by the diffused Zn atoms and multiply under a stress induced during the diffusion process, It is concluded that the dark defects are attributed to the dislocation loops where minority carriers recombine nonradiatively.