EVOLUTION OF EELS AND AES DURING FORMATION OF THE SI(111)7X7 A-SI INTERFACE/

The evolution of intensity and energy position of peaks in the electro n energy loss spectra (EELS) and Auger electron spectra (AES) of Si de posited on the 7x7-reconstructed Si(111) surface. at room temperature has been studied as a function of the Si thickness in the 0-6.5 bilaye rs (BL) range, It has been found that intensities of both bulk plasmon loss (h) over bar omega(b) and L23VV Auger line decay significantly f aster (at 0-0.1 and 0-0.3 BL, respectively) than in a simple model of the growth process without a-Si/Si(111) interface reconstruction and i nteraction. It has been shown that these decay rates can be connected with the transition of 7x7 adatoms into a disordered state and with a, decrease in the density of filled p-sates in the valence band of the a-Si monolayer. The decay rate of the bulk plasmon loss peak and pertu rbations of the amplitudes and energy positions of surface loss peaks at 0-0.1, 0.1-0.3, 0.3-0.7 and 0.7-1.6 BL show a five-step mechanism o f the a-Si growth. A structural model and formation mechanism of the a -Si/Si(111)7x7 interface are also proposed.