Weak localization in variable-concentration embedded phosphorus delta layers in silicon produced by variable PH₃ dosing

The key building block for devices based on the deterministic placement of dopants in Si is the formation of P dopant monolayers and the overgrowth of high quality crystalline Si. Lithographically defined dopant δ-layers can be formed with an STM, which can pattern device features on a H-terminated silicon surface by exposing Si dangling bonds at specific locations and placing P at these locations with atomic precision by exposing the surface to PH₃. The motivation for this research is to advance the dopant formation and overgrowth processes necessary to produce prototypical few-atom devices in a controlled solid-state environment. Our earlier work has demonstrated that a careful magnetotransport study at low T, along with analysis of the weak localization (WL) feature, allows us to extract parameters associated with the electronic transport that offer a meaningful quantitative characterization of δ-layer quality and dopant diffusion, with better resolution than the more commonly used SIMS. We build on this work by examining the effect on the transport and WL behaviors in a set of samples with Si:P delta layers produced with different PH₃ exposure procedures prior to a standard Si encapsulation. Here, we describe the overall methodology and the findings of this study.