Doped semiconductor nanocrystal junctions

Semiconductor junctions are the basis of electronic and photovoltaic devices. Here, we investigate junctions formed from highly doped (ND 1020 1021cm 3) silicon nanocrystals (NCs) in the 2-50 nm size range, using Kelvin probe force microscopy experiments with single charge sensitivity. We show that the charge transfer from doped NCs towards a two-dimensional layer experimentally follows a simple phenomenological law, corresponding to formation of an interface dipole linearly increasing with the NC diameter. This feature leads to analytically predictable junction properties down to quantum size regimes: NC depletion width independent of the NC size and varying as N 1=3 D , and depleted charge linearly increasing with the NC diameter and varying as N1=3 D . We thus establish a "nanocrystal counterpart" of conventional semiconductor planar junctions, here however valid in regimes of strong electrostatic and quantum confinements