Surface depletion effects in semiconducting nanowires having a non-uniform radial doping profile

Abstract

Doping profile has a significant effect on nanowire (NW) electrostatics, an effect that is expected to influence NW contact and transport properties. Herein, the electrostatic potential of nanowires (NWs) of non-uniform radial doping is calculated by two means: depletion approximation and a numerical calculation. Two profiles are considered: linear and exponential, corresponding to shallow and abrupt distributions; the results are compared to planar systems with similar doping profiles, and to uniformly doped NW systems. For a given average doping distribution, a non-uniform doping profile results in significantly lower carrier concentrations, an effect which intensifies with doping non-uniformity. Furthermore, in some cases, band diagrams obtained for the exponential doping profile vary greatly from any uniform doping, indicating that unique properties are expected for such NWs.