A SURFACE EXTENDED X-RAY-ABSORPTION FINE-STRUCTURE STUDY OF TELLURIUMADSORBED 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 w ave spectroscopy (XSW). This particular system is of interest due to i ts potential applicability in the surfactant aided growth of CdHgTe-Cd Te-Si(100) based infra-red detectors. The Te/Si(100) structure was gen erated by depositing a thick layer (similar to 100 Angstrom) of CdTe o nto 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 sur face 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 p hoton energy range of 4440-4700 eV, was probed using a total yield det ection scheme. The SEXAFS results indicated that the Te atoms sat in 2 -fold bridge sites directly above a fourth layer Si atom, The correspo nding bond length was measured to be 2.52 +/- 0.05 Angstrom. The XSW m easurements 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, Th ese results are compared with those of Bennet et al, who examined a si milar system using soft X-ray photoemission (SXPS) and the STM study o f Yoshikawa et al.