ION CHANNELING INVESTIGATION OF THE LATTICE LOCATION OF SN ATOMS IN GAAS THIN-FILMS GROWN BY MOLECULAR-BEAM EPITAXY

We have investigated the lattice location of Sn atoms in Sn-doped GaAs thin films grown by molecular beam epitaxy using ion channeling techniques. Accumulation of ≊2×1014 atoms/cm2 of Sn on the GaAs surface was detected. These surface Sn atoms were determined to be randomly distributed within ≊20 Å of the surface of the GaAs. Angular scans of the Ga Kα, As Kβ, and Sn L x rays across the 〈100〉, 〈110〉, and 〈111〉 axial channels indicated that the Sn atoms in the GaAs layer are mostly substitutional. No displacement of the Sn atoms larger than 0.14 Å from the substitutional sites was detected.