Arsenic-Antisite-Related Defects in GaAs Grown at Low Temperature: Charaterization of Localized States

Arsenic interstitials and interstitial complexes in low-temperature grown GaAs

“…This complex contributes less lattice dilation per excess As atom than an isolated interstitial, in agreement with experimental evidence that the excess As which is not accounted for by measured antisite concentrations contributes only a small amount to the net lattice dilation. The binding energy of the split antisite, and the binding energy of the nearest-neighbor interstitial-antisite complex, which has been discussed previously, 32,33 are low, suggesting that these complexes may be continuously forming, breaking up, and transforming into each other. Therefore, these interstitialantisite complexes may be responsible for a donor band, instead of two separate donor levels.…”

“…Like the defects responsible for the 0.3-0.5 eV donor band, the nearest-neighbor complex has the EPR and absorption signatures characteristic of an As antisite. 32,33 Like the defects responsible for this band, and unlike the isolated antisite, the antisite-interstitial complex is unphotoquenchable. 32,33 The 0.3-0.5 eV band is the dominant donor band in some samples grown around 350°C.…”

“…32,33 Like the defects responsible for this band, and unlike the isolated antisite, the antisite-interstitial complex is unphotoquenchable. 32,33 The 0.3-0.5 eV band is the dominant donor band in some samples grown around 350°C. 34 In fact, we have previously predicted that the excess As might be expected to be present in low-energy complexes, including antisite-interstitial complexes, rather than in configurations dictated by the kinetics of growth, in LT GaAs grown around 400°C.…”

“…The electronic band structure of this complex contains an antisite-derived level in the midgap region and an antisite-derived resonance in the conduction band. 33 Therefore, this complex will have the EPR and absorption signatures characteristic of an As antisite. However, since it contains an interstitial as well, it contributes one extra As to the excess As which is not accounted for by the measured concentrations of As antisites.…”