EL2 distributions in doped and undoped liquid encapsulated Czochralski GaAs

Publisher Website
Google Scholar
Abstract
We compare the longitudinal and radial distributions of EL2 in undoped semi-insulating and intentionally doped n-type GaAs crystals grown by the liquid encapsulated Czochralski technique. Longitudinal profiles in undoped crystals are controlled by changes in melt stoichiometry as the crystal is pulled from the melt. EL2 profiles along crystals doped above about 1×1017 cm−3, on the other hand, are controlled primarily by the carrier concentration as a result of the suppression of EL2 by free electrons. Radial EL2 profiles are typically W shaped and M shaped in undoped and doped (above threshold) crystals, respectively. The origin of these radial profiles is discussed in terms of residual stress, melt stoichiometry, and the suppression of EL2 by electrons. Our results are also discussed in the light of the antisite model for EL2.