Energy-selective reaction of the hydrogen-passivated Si surface with carbon tetrafluoride via dissociative electron attachment

We report the partial fluorination of a H-passivated, sputtered Si(111) surface at 35 K induced by irradiating a physisorbed carbon tetrafluoride overlayer with 2-13 eV electrons. The reaction cross section depends strongly on the energy of incoming electrons with a threshold at 4.0 eV and a clear resonance peak at 6.0 eV having a maximum value of 4.8 X 10(-17) cm(2), which is attributed to dissociative electron attachment (DEA) to CF4. Our study demonstrates the energetic selectivity of DEA for chemically modifying a semiconductor surface.