Ultrafast carrier dynamics near the Si(100)2x1 surface

We present a time-resolved photoemission study of carrier dynamics near the Si(100)2x1 surface. It is found that the dominant contribution to the phot oemission process originates from defect states on the Si(100)2x1 surface. Enhanced optical absorption is observed for these defect slates and carrier exchange between these states and the bulk is observed. The electron densi ty near the surface and the shape of the electron energy distribution are f ound to change on a very fast time scale. A simple theoretical model is est ablished to extract transport parameters from the observed electron energy distribution. [S0163-1829(99)07107-6].