Towards Fabrication of Atomic Dopant Wires via Monolayer Doping Patterned by Resist-Free Lithography

Abstract

Fabrication of atomic dopant wires at large scale is challenging. We explored the feasibility to fabricate atomic dopant wires by nano-patterning self-assembled dopant carrying molecular monolayers via a resist-free lithographic approach. The resist-free lithography is to use electron beam exposure to decompose hydrocarbon contaminants in vacuum chamber into amorphous carbon that serves as an etching mask for nanopatterning the phosphorus-bearing monolayers. Dopant wires were fabricated in silicon by patterning diethyl vinylphosphonate monolayers into lines with a width ranging from 1 μm down to 8 nm. The dopants were subsequently driven into silicon to form dopant wires by rapid thermal annealing. Electrical measurements show a linear correlation between wire width and conductance, indicating the success of the monolayer patterning process at nanoscale. The dopant wires can be potentially scaled down to atomic scale if the dopant thermal diffusion can be mitigated.

Silicon Doping by Polymer Grafting: Size Distribution Matters

“…For instance, arylphosphonic acids have been used to engineer the electronic properties of atomically thin sheets of semiconducting transition-metal dichalcogenides . Doping of silicon and other bulk semiconductors has been achieved by means of SAM of P-containing molecules in the so called monolayer doping approach. ,,− This approach relies on the formation of a SAM over the semiconductor surface and subsequent injection of the dopant into the substrate by a high-temperature thermal treatment. The described procedure has been used to enable the formation of sub 5 nm ultrashallow junctions in Si. , Interesting exploitation perspectives are also expected for photovoltaic applications, which usually require effective approaches to reduce the cost of the devices .…”