Trap Suppression by Isoelectronic In or Sb Doping in Si-Doped n-GaAs Grown by Molecular-Beam Epitaxy

摘要

The effects of isoelectronic doping of GaAs by In or Sb on the electron deep levels in n-GaAs grown by molecular-beam epitaxy have been investigated in the growth temperature range 500-600 C for Si doping levels of 4-7 x 10 to the 16th power/cc and As-stabilized conditions. The two dominant traps M3 and M6 are drastically reduced in concentration by up to three orders of magnitude for M3 and two and a half orders of magnitude for M6 by introducing 0.2-1 at.% In or Sb and increasing growth temperatures from 500 to 550 C. The trap concentrations of M3 and M6 were also significantly reduced by increasing the growth temperature to 600 C without In or Sb doping and by decreasing the growth rate from 1.0 to 0.3 micrometers/h. The incorporation coefficients of In and Sb have been measured and are found to decrease with increasing growth temperature. The growths with high M3 and M6 trap densities are shown to have short minority-carrier diffusion lengths. Indium isoelectronic doping, which is presumed to take place on a gallium sublattice site, and Sb doping, which is expected to take place on an arsenic sublattice site, appear to have rather similar effects in suppressing the concentration of the M3 and M6 electron traps. This suggest that both of these traps are in some way related to (V sub As V sub Ga) complexes or (V sub As XV sub Ga) complexes where X is different for M3 and M6 and might be interstitial or impurity related. Reprints. (AW)