CORE-LEVEL SPECTRA OF CLEAN 2X8 VICINAL SI(110)

Clean and single domain Si(110) surfaces have been prepared using wafe rs cut along a properly chosen vicinal angle which gives a sharp ''8 X 2'' reconstruction: the choice of the angle is such that the surface unit cell is reduced and better ordered than the multidomain ''2 X 16' ' reconstructed nominal (110) face as checked by LEED. The Si-2p core level spectra were obtained on the high resolution SU3 line at LURE (O rsay, France). They were taken at several surface and bulk sensitive s ynchrotron photon energies from 110 to 150 eV. Examples of decompositi ons of such spectra into bulk and surface components show that the pre sently unknown structure of the (110) face of Si should involve simila r local structures especially adatoms and dimers as the well-known (7 X 7) reconstructed Si(111) surface.