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

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 mono- and 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.