Angular resolved surface-plasmon loss from Si(111) surfaces

The dispersion of plasmon-loss peaks measured with angle resolved electron energy loss spectroscopy gives evidence of increased surface carrier concentration from B-doped (10 sup (15)-10 sup (16) cm sup (-3)) Si(111) surfaces. Low energy 10-20 meV loss peaks were detected on ion sputter cleaned and annealed surfaces at temperatures between 800C and 1250C which had energies dependent on surface defect density and thus were assigned to free carrier plasmons. 

Various momentum-transfer values were obtained by varying the incidence angle from 45degrees to 75degrees with the detector constant at 60degrees, and by varying the incident electron energy from 5 eV to 20 eV.