Nonuniform doping distribution along silicon nanowires measured by Kelvin probe force microscopy and scanning photocurrent microscopy

Abstract

We use Kelvin probe force microscopy and scanning photocurrent microscopy to measure the doping distribution along single phosphorous-doped silicon nanowire grown by the vapor-liquid-solid method. A nonlinear potential drop along biased silicon nanowires is detected both by measuring the surface potential directly via Kelvin probe force microscopy and by integrating the photocurrent measured by scanning photocurrent microscopy. These variations in the potential and field are further analyzed to extract the longitudinal dopant distribution along an individual silicon nanowire. The results show a very good agreement between the two methods to quantitatively detect potential, field, and doping variations within doped silicon nanowires.