A comprehensive study on the physicochemical and electrical properties of Si doped with the molecular doping method

Abstract

Semiconductor doping through solution-based self-assembling provides a simple, scalable, and cost-effective alternative to standard methods and additionally allows conformality on structured surfaces. Among the several solution-based deposition techniques, dip coating is the most promising. It consists in immersing the target to be doped inside a solution containing the dopant precursor. During this process, the molecule bonds to the target surface with a self-limiting process ruled by its steric properties. Successive annealing leads to layer decomposition and diffusion of dopant atoms inside the substrate. Most of the work on molecular doping lacks information on the molecule/Si interface chemical properties, on the mechanisms of the molecule evolution during the coating, and of its decomposition after the diffusion step. Moreover, it has so far been devoted to the molecules design to tune the final dopant dose and distribution. Here, the main results on the molecular doping are reviewed, and new findings on the interface characteristics, also in terms of monoand multilayers formation are presented. A systematic study, carried out by fixing the dopant precursor and varying the coating conditions, is also reported, demonstrating that the important doping features can be controlled precisely and that uniformity can be achieved at nanometer level.

Phosphorus monolayer doping (MLD) of silicon on insulator (SOI) substrates

“…6) has the potential to inhibit diffusion into the substrate. Other research groups [7–8 18], working on P diffusion doping using a variety of techniques have also seen limitations at 2 × 10 19 cm −3 .…”

Silicon Quasi‐One‐Dimensional Nanostructures for Photovoltaic Applications

“…Morphological characterization showed the successful elimination of the residual gold agglomerates. SiNWs were doped by molecular monolayer doping, an innovative method that consists in immersing the Si substrate to be doped inside a liquid solution composed of the chemical precursor of the dopant at high temperature [28]. This process leads to the formation of a monolayer of molecules containing the dopant atoms.…”

“…A few approaches presented in the literature propose to add a layer of intrinsic Si between the inner and outer regions, forming a p-i-n coaxial junction [9], in order to increase the effect of the electric field of the depleted region during the charge separation process. Regarding the doping methods for the SiNWs, conventional routes, such as gas source-based techniques or ion implantation [18], will be described, as well as the new cost-effective approach called molecular monolayer doping (MD), consisting in immersing the Si to be doped inside a liquid solution with dopant chemical precursors [28]. The techniques of formation SiNHs will be then considered [10,29].…”

Monolayer Doping of Si with Improved Oxidation Resistance

“…Samples were capped with a 50 nm layer of SiO 2 via sputtering and transferred to a rapidthermal-anneal tool where the substrates were subjected to a 5 s anneal at 1050 ο C, based on parameters from our previous work and other P-MLD reports 50 , under a nitrogen atmosphere.…”