IN-SITU OBSERVATION OF CHARGE-EXCHANGE AND SURFACE SEGREGATION OF HYDROGEN DURING LOW-ENERGY H-2(+) SCATTERING FROM SEMICONDUCTOR SURFACES(AND H)

The charge-exchange and diffusion/segregation dynamics of hydrogen has been investigated for Si(111), beta-B(100), and YB66(100) surfaces. T he backscattered proton yield during H-2(+) ion bombardment of the sur faces increases significantly with the irradiation time. This increase occurs because (i) the implanted hydrogen tends to segregate to the o utermost surface layer and then passivates the active dangling bonds a nd (ii) energetic protons backscattered from the solid preferentially capture the dangling-bond electrons via transient chemisorption just b efore the protons leave the surface.