Hole carrier density and mobility of aluminum delta-doped layers in silicon

We have measured the hole carrier density and mobility of a two-dimensional hole gas in aluminum delta-doped layer in silicon with a narrow doping profile and high carrier density. The p-type delta layer has not been well studied unlike a n-type delta layer by phosphine gas dosing. I will present our Hall measurements at 4 K using mesa-etched Hall bar device fabricated in Al delta-doped layer in Si with the hole carrier concentration, n_p ≈ 1.6 x 10¹⁴ /cm², and mobility, μ_h ≈ 15 cm²/Vs. These densities are close to where a theoretical study predicted superconducting Si heavily doped with Al near 1 K [1], opening up possibilities for semiconductor/superconductor hybrid systems. Comparison of STM analysis and Hall measurements show ≈ 1.1 ± 10 % holes per dopant atom.
[1] Bourgeois and Blase, Appl. Phys. Lett, 90 142511 (2007).