Charge distribution on and near Schottky nanocontacts

Schottky nanocontacts are formed when nm-sized metal particles are located on the planar surface of a doped semiconductor. The charge distribution on and near such nanocontacts is analyzed in the case of disc-shaped particles. The results of calculations are presented as a function of particle size, semiconductor permittivity, dopant concentration, and Fermi level difference. In contrast to macroscopic junctions, the charging of the metal particle is demonstrated to be proportional to the Fermi level difference and accordingly to the potential difference between the metal and semiconductor, so that the junction exhibits a constant capacitance. The charging of the metal-vacuum metal surfaces may be appreciable, especially for relatively low values of the semiconductor permittivity. The tunneling barrier width at half height is shown to be close to, or less than, 3/8 of the disc diameter. (c) 2006 Elsevier B.V. All rights reserved.