Growth and characterization of atomic layer doping structures in Si

A new method to fabricate atomic layer doping structures in silicon using a combination of molecular-beam epitaxy and solid-phase epitaxy is developed. The antimony dopants are restricted to a thickness less than the resolution limit of secondary ion mass spectrometry, and exhibit extremely sharp C-V carrier profiles of less than 2 nm for a single Sb monolayer (ML). Hall and resistivity data show full activation for 0.1 ML and saturation at 8×1013 electrons cm−2. Measurements down to 4 K show metallic conduction for highly doped samples (above 0.05 ML) two-carrier conduction for intermediate levels, and strong freezeout for low amounts of Sb (below 0.01 ML). The two-dimensional electron gas is shown to exist by angular dependence of magnetoresistance.