A surface extended X-ray absorption fine structure study of tellurium adsorbed onto Si(100)

The adsorption of tellurium on Si(100) has been studied using surface extended X-ray adsorption fine Structure (SEXAFS) and X-ray standing wave spectroscopy (XSW). This particular system is of interest due to its potential applicability in the surfactant aided growth of CdHgTe-CdTe-Si(100) based infra-red detectors. The Te/Si(100) structure was generated by depositing a thick layer (similar to 100 Angstrom) of CdTe onto a dean Si (2 x 1) double domain surface, and annealing the sample to 350 degrees C, This resulted is a similar to 1 ML Te terminated surface where the (2 x 1) reconstruction was lost in favour of a (1 x 1) symmetry, X-ray absorption of the Te L(3) edge (E = 4341 eV), with a photon energy range of 4440-4700 eV, was probed using a total yield detection scheme. The SEXAFS results indicated that the Te atoms sat in 2-fold bridge sites directly above a fourth layer Si atom, The corresponding bond length was measured to be 2.52 +/- 0.05 Angstrom. The XSW measurements of the (400) reflection gave a coherent position of 1.63 +/- 0.03 Angstrom and a coherent fraction of 0.65 . This is consistent with the breaking of the Si-Si dimers and thus could be an example of the phenomena of adsorbate-induced dereconstruction of the surface, These results are compared with those of Bennet et al, who examined a similar system using soft X-ray photoemission (SXPS) and the STM study of Yoshikawa et al.