Ultradense phosphorous delta layers grown into silicon from PH3 molecular precursors

Phosphorous delta-doping layers were fabricated in silicon by PH3 deposition at room temperature, followed by low-temperature Si epitaxy. Scanning tunneling microscope images indicate large H coverage, and regions of c(2x2) structure. Hall data imply full carrier activation with mobility <40 cm(2)/V s when the surface coverage is less than or similar to0.2 ML. Conductivity measurements show a ln(T) behavior at low temperatures, characteristic of a high-density two-dimensional conductor. Possible future applications to atom-scale electronics and quantum computation are briefly discussed. (C) 2002 American Institute of Physics.