Photoluminescence, deep level transient spectroscopy and transmission electron microscopy measurements on MeV self-ion implanted and annealed n-type silicon

Abstract

Deep-level transient spectroscopy (DLTS), photoluminescence (PL), and transmission electron microscopy (TEM) measurements have been made on n-type silicon after implanting with 5.6 MeV Si3+ ions using doses of 109–1014 cm−2 and anneals at 525 and 750 °C. In all the samples, there is only a small dependence of the widths and energies of the PL zero-phonon lines on implantation dose, allowing the high resolution of PL to be exploited. In samples annealed at 525 °C, the PL intensity can provide a measure of the concentration of defects over the implantation range, 109–1012 cm−2. Carbon-hydrogen complexes are identified as transient species with increasing dose, and the “T” center is related to a DLTS trap 0.20 eV below the conduction band energy Ec. At the highest doses in these samples, TEM imaging shows the presence of nanometer-sized clusters, and the PL spectra show that many previously unreported defects exist in the implanted zone, in addition to two broad bands centered on ∼885 and ∼930 MeV. The multiplicity of defects supports recent suggestions that a range of interstitial complexes is present in the annealed samples. Annealing at 750 °C produces complete recovery in both the DLTS and PL spectra for doses of less than 1013 cm−2. At higher doses, {113} self-interstitial aggregates are observed in TEM, along with the “903” PL signal associated with the {113} defects, and the Ec−0.33 eV “KA” DLTS trap. These data support the recent identification of that trap with the {113} defects. The well-resolved PL spectra show that many previously reported defects also exist in samples implanted with a dose of 1014 cm−2 and annealed at 750 °C, again implying the presence of a range of interstitial complexes.