Significant resistance reduction in modulation-doped silicon nanowires via aluminum-induced acceptor states in SiO${}_2$

Silicon nanowires (Si NWs) like structures in the form of nanosheets are the building blocks for future transistors in the most advanced complementary metal-oxide-semiconductor technologies. However, Si NWs with few nanometers in diameter suffer from severe difficulties with respect to efficient impurity doping. These difficulties can be overcome by a novel doping concept for Si NWs comparable to the modulation doping approach known from III-V semiconductors. Modulation doping means that the parent dopant atoms are spatially separated from the volume that is to be doped by embedding them into an adjacent material with a higher bandgap. Herein, Al-doped SiO${}_2$ shells around the Si NWs are used for the experimental realization of modulation doping. In two independent experiments, a significant reduction of the electrical resistance of Si NWs by several orders of magnitude is measured, when compared to the resistance of Si NWs with undoped SiO${}_2$ shells. The results are discussed in the context of modulation doping by the surface functionalization with SiO${}_2$:Al shells. (© 2023 The Authors. physica status solidi (a) applications and materials science published by Wiley‐VCH GmbH)