Microscopic four-point-probe resistivity measurements of shallow, high density doping layers in silicon

We present room temperature resistivity measurements of shallow, monolayer doped phosphorus in silicon, a material system of interest for both conventional microelectronic manufacturing, and future quantum electronic devices. Using an in-situ variable spacing microscopic four-probe system, we demonstrate the ability to separate the conductivity of the substrate and the doping layer. We show that the obtained sensitivity to the dopant layer derives from a combination of the nanoscale contacting areas and the conductivity difference between the highly doped 2D layer and the substrate. At an encapsulation depth of only 4 nm, we demonstrate a room temperature resistivity of 1.4k Omega/square. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4773485]