VAPOR-PHASE EPITAXIAL GROWN GAAS FILMS WITH A VERY-LOW DEEP-LEVEL CONCENTRATION

Isovalent indium doping was employed in order to decrease the deep lev el concentration in n-type GaAs:S films grown by the vapour phase epit axy in a chloride system. The EL2 electron trap was found to be the do minant deep level in the films with a low donor concentration. Using i sovalent In doping, the concentration of this deep level was reduced f rom about 1x10(14) cm(-3), which was typical of the GaAs:S films, to a value less than the deep level transient spectroscopy (DLTS) sensitiv ity threshold (< 2.5 X 10(12) cm(-3)). In the case of heavily sulphur doped films, a strong decrease in the deep level concentration was det ected by photoluminescence when isovalent indium doping was used. The suppression of the deep-level-related lines was accompanied by an enha ncement of the band-to-band radiative recombination. All the effects w ere found to appear in a narrow region close to an indium content of 1 x10(20) cm(-3)