Defects due to nonstoichiometric growth in semi-insulating GaAs and their effects on Si implantation activation efficiency

The effects of starting semi-insulating GaAs conditions on Si-implantation activation efficiency have been studied by capacitance deep level transient spectroscopy, 4.2-K photoluminescence, and thermally stimulated current spectroscopy. Experimental evidence shows that samples with good Si activation efficiency have higher EL2 trap concentration, compared with samples with a lower activation efficiency, and a higher density of trap T₂ at E_v +0.49 eV believed to be the native defect As_Ga++. For samples with a lower activation efficiency, a deep trap T₃ attributed to either V_As or Ga_As -V_Ga appears at E _v +0.44 eV with a concentration larger than that of T₂. A PL emission at 1.44 eV due to Ga_As or its related complex is observed in the samples with a lower activation efficiency, but not in samples with good activation efficiency. Comparison between samples grown under Ga-rich or As-rich conditions and samples that show different activation efficiencies confirms that growth stoichiometric conditions largely determine the Si implantation activation efficiency.