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 electron beam from the growing surface have been measured by recently developed energy filtered RHEED apparatus. AES measurements and RHEED observations were also pursued to obtain information on the amount of deposited Li and on the surface structural change, respectively. At the beginning of the deposition, Auger intensity ratio, Li(KLL)/Si(LVV), increases in proportion to the deposition time, and thereafter the ratio is saturated at nearly the same time Debye-Scherrer ring of Li appears 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.