Polarization-directed growth of single-crystalline silicon nanostructures

Polarization-directed growth is a special laser directing method enabling relatively large-scale fabrication of orientation-controlled subwavelength nanostructures; however, controlling the atomic arrangement of the deposition is challenging and reported structures are predominantly amorphous. In this work, we demonstrate the direct growth of single-crystal silicon nanostructures with lateral dimensions under 40 nm on Al₂O₃ substrates, achieving precise orientation control via polarized laser excitation. High-resolution transmission electron microscopy (HRTEM) confirmed the excellent crystallinity of the silicon structures and revealed that about 80% of them grew along the [111] orientation parallel to the laser polarization. Finally, through FDTD simulations and two-temperature model calculations, we believe that strong anisotropic field enhancement and high interfacial temperatures at the growth front contribute to polarization-directed single-crystalline silicon growth.