Scanning Near-field Photocurrent measurements on B-implanted Si(100)

We report near-field photocurrent (NPC) measurements performed on three different silicon samples characterized by different implantation doses. The images were acquired at Ć=1330nm corresponding to a photon energy of 0.93eV that is below the silicon energy gap (Egap=1.12eV). The NPC images reveal the presence of boron clusters which are a consequence of B- implantation and rapid thermal annealing. Depending on the level of boron concentration the photocurrent shows intensity varying between two orders of magnitude. Boron clusters behave as metal clusters embedded into the silicon matrix and introduce gap states which give rise to the observed photocurrent.