Scalable and Tunable In-Plane Ge/Si(001) Nanowires Grown by Molecular Beam Epitaxy

TL;DR

This paper introduces a low-temperature epitaxial method for growing high-quality, in-plane germanium nanowires with high hole mobility on SiGe/Si substrates, enabling scalable nanoelectronic and quantum device applications.

Contribution

It presents a novel, scalable growth technique for pure germanium nanowires with high mobility using pre-patterned templates and temperature control.

Findings

Nanowires exhibit hole mobility exceeding 7000 cm²/Vs at 2-20 K

Growth method suppresses Si-Ge interdiffusion effectively

Nanowires are precisely positioned and shaped on substrates

Abstract

Germanium nanostructures offer significant potential in developing advanced integrated circuit and disruptive quantum technologies, yet achieving both scalability and high carrier mobility remains a challenge in materials science. Here, we report an original low-temperature epitaxial method for growth of site-controlled in-plane germanium nanowires with high hole mobility by molecular beam epitaxy. By reducing the growth temperature, we effectively suppress Si-Ge interdiffusion, ensuring pure germanium composition within the nanowires while preserving their high crystalline quality. The method employs pre-patterned ridges on strain-relaxed Si$_{0.75}$Ge$_{0.25}$/Si(001) substrates as tailored templates, enabling control over the position, length, spacing and cross-sectional shape of the nanowires. Electrical measurements of field-effect devices made from as-grown germanium nanowires show that the nanowires are of hole conduction with mobility exceeding 7000 cm$^{2}$/Vs at 2-20 K. The method paves a way for fabrication of scalable germanium nanowire networks, providing a reliable platform for the developments of high-performance nanoelectronics and multi-qubit chips.