Electronic structure of GaF[sub 3] films grown on GaAs via exposure to XeF[sub 2]

GaAs(110) and (100) wafers are reacted with XeF[sub 2] at room temperature and studied with soft-x-ray photoelectron spectroscopy (SXPS), photon-stimulated desorption (PSD) and electron-energy-loss spectroscopy (EELS). The reaction between GaAs and XeF[sub 2] results in the homogeneous growth of a GaF[sub 3] film and an interface region consisting of intermediate products. The band gap of GaF[sub 3] and its band lineup with the GaAs substrate are determined via EELS and SXPS. F[sup +] PSD spectra collected after the initial XeF[sub 2] exposures indicate a single desorption onset at [similar to]28 eV, due to the excitation of a F 2[ital s] electron to the GaAs conduction-band minimum. PSD spectra collected after larger exposures contain a number of features due to transitions within the GaF[sub 3] band structure. These features appear when the film thickness exceeds [similar to]10 A, indicating that the bulk electronic structure has developed. Annealing the film to [similar to]250 [degree]C results in the inhomogeneous removal of GaF[sub 3].