Conversion-electron extended x-ray-absorption fine-structure measurements of ion-damaged GaAs

Extended x-ray-absorption fine-structure (EXAFS) measurements of ion-implanted GaAs have been made using conversion-electron detection. This total-electron-yield detection technique (termed CEEXAFS) allows near-surface sensitivity with a sampling depth of 700–1000 Å. Measurements of the Ga absorption edge show that implantation of ${10}^{16}$ ${\mathrm{cm}}^{\mathrm{-}2}$ of Zn ions at 180 keV into GaAs produces heavy lattice damage (amorphization) to a depth of about 700–900 Å. After rapid thermal annealing, the amorphous layer is found to be recrystallized and structurally indistinguishable from unimplanted material. The sampling depth of CEEXAFS has been measured for the first time, using standards with known depth-dependent structure. The CEEXAFS technique greatly reduces Bragg-peak contamination of the EXAFS signal from single-crystal materials, and allows measurement of a variety of samples which cannot be fabricated as thin layers for conventional transmission or fluorescence EXAFS measurements. The method permits examination of the local environment of host atoms (in this case Ga) in the near-surface region without interference from the underlying bulk and without the distortions found in fluorescence EXAFS measurements of concentrated samples.