ENERGY-LOSS SPECTROSCOPY FOR LI SI BY ENERGY-FILTERED RHEED/

While depositing Li atoms on a Si(111) 7 X 7 clean surface being kept at about 170 degrees C, energy loss spectra of specularly reflected el ectron beam from the growing surface have been measured by recently de veloped energy filtered RHEED apparatus. AES measurements and RHEED ob servations were also pursued to obtain information on the amount of de posited Li and on the surface structural change, respectively. At the beginning of the deposition, Auger intensity ratio, Li(KLL)/Si(LVV), i ncreases in proportion to the deposition time, and thereafter the rati o is saturated at nearly the same time Debye-Scherrer ring of Li appea rs in the RHEED pattern, that is, Stranski-Krastanov growth mode. For the series of Li depositions, energy loss spectra of the specular beam showed interesting change. It has been found that a new peak appears at about 19 eV in addition to surface plasmon loss peaks of Si when Li islands begin to grow. This new peak is supposed to be a coupled loss peak of the surface plasmon of Si (12 eV) with the bulk plasmon of Li (7 eV). (C) 1998 Elsevier Science B.V. All rights reserved.