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.