Stable, Step-Guided Growth of Planar Germanium Nanowires at 200 °C via the In-Plane Solid-Liquid-Solid Mechanism

Germanium nanowires (GeNWs) are an ideal 1D platform for advanced nanoelectronics and optoelectronics, offering high carrier mobility, strong quantum confinement effects, and full compatibility with silicon-based complementary metal-oxide-semiconductor (CMOS) technology. However, achieving stable guided growth of planar GeNWs via the in-plane solid-liquid-solid (IPSLS) mechanism has remained challenging due to rapid intermixing between the catalytic droplet and the amorphous germanium (a-Ge) precursor. This study investigates the previously overlooked role of the absorption rate in stabilizing the interface between the indium (In) droplet and the a-Ge layer. A comprehensive analytical growth model elucidates the key dynamic processes governing mass transport and droplet stability during IPSLS growth. Systematic parametric studies identify a critical parameter window, enabling the guided growth of ultralong and uniform germanium nanowires with lengths exceeding 10 µm and diameters of ≈30 nm at a remarkably low growth temperature of 200 °C. These findings advance the understanding of the IPSLS growth mechanism and demonstrate precise control over GeNW morphology, opening new avenues for transformative applications in high-performance electronics, optoelectronics, and flexible sensing technologies.