On the nature of the silicon activation efficiency in liquid-encapsulated Czochralski-grown GaAs by photoluminescence

Abstract

Evidence of native gallium antisite defects in semiinsulating liquidencapsulated Czochralskigrown GaAsThe shallow defect evolution in Si-implanted and -annealed liquid-encapsulated Czochralskigrown GaAs is investigated by photoluminescence experiments. Three major emission lines are found. The first emission line located at 1.492 eV corresponds to the Si Ga -CAS radiative recombination. The remaining two lines located at 1.44 and 1.40 eV are shown to correspond to Gal-Si.",s and VAs-Si As radiative recombinations, respectively. The effects of these three shallow centers on the silicon activation efficiency are discussed with respect to different annealing and implantation conditions. 1246

Major Implantation‐Induced Defects in Conventional and Rapid Annealed, Silicon Implanted LEC‐Grown GaAs

“…The depth of the defect in the bulk increases as the implantation energy increases. But, Ga interstitials were observed to be a shallow donor in the proximity of Eo -ET = 50 MeV in our photoluminescence study (24). 4 where the trap penetrates deeper into the bulk as one increases the implantation fluence.…”

“…Since the defect is a donor-like electron trap, attributing this center to YGa is ruled out. Considering As vacancies to be the origin of this donor is not possible for the following reason: As vacancies were found to increase with increasing annealing temperatures as observed in our earlier photoluminescence work (24). Therefore, in this study, one would expect to see an increase in the concentration of the deep donor lying between Ec -0.88 eV and Ec -1.09 eV with increasing annealing temperature if this center were attributed to As vacancies.…”

“…To show that this trap is implan-tati0n-induced, we examined its depth distribution as a function of (i) implantation energy and (ii) implantation fluence. Considering As vacancies to be the origin of this donor is not possible for the following reason: As vacancies were found to increase with increasing annealing temperatures as observed in our earlier photoluminescence work (24). The depth of the defect in the bulk increases as the implantation energy increases.…”

Modeling Activation of Implanted Si in GaAs

“…Because the activation-rate time constant, ~, varies inversely with k, we expect 9 to be smaller at higher temperatures. Therefore it will take less time for the implanted profile to reach the equilibrium active profile at ,~ 0.9 (0.55~ 9 MH~ = 1.9 exp \-k~-/ [30] Equation [22] shows the terms that 9 represents. It is possible to approximate the reaction rate constant k by estimating the Ga vacancy concentration in 7.…”

“…Photoluminescence studies for isochronal anneals show a gradual increase in the intensity up to 850~ for a peak that contains Si~. The peak intensity decreases as the temperature exceeds 850~ (30). It is possible that at the lower temperatures, their samples were not annealed long enough to reach the higher equilibrium activation.…”