Preparation of silicon nanowires by in situ doping and their electrical properties

Abstract

Individual silicon nanowires (SiNWs) doped by in situ dopant incorporation during growth of the SiNWs was investigated. Electrical charge transport measurements were taken before and after removing the material from the boron-doped SiNW surfaces by wet chemical etching. AFM (atomic force microscopy) images showed the radial cross section of the ∼10nm thick material that was cut off from the SiNW surface. The electrical transport characteristics after each etching cycle revealed the radial core–shell distribution of the activated dopants. The carrier concentration close to the surface of the boron-doped SiNWs was a factor of 6 higher than the value in the core. Using a simple, rapid and reliable technique, the natural distribution of the surface dopants in the SiNWs, which was distinct from many top-down fabricated NWs, explained the enhancement in the charge transport properties of these NWs. This could yield robust properties in ultra-small devices that are often dominated by random dopants fluctuations.