Centimeter-scale free-standing flexible 3C-SiC films by laser chemical vapor deposition

Abstract

Flexible 3C-SiC is considered a promising material for durable and adaptable electronics serving in harsh environments due to its chemical stability, high electron mobility, and wide bandgap. However, the application of flexible 3C-SiC is limited by the difficulty in producing large-scale free-standing films with excellent mechanical properties. Herein, centimeter-scale (1.5 × 1.2 cm²) free-standing 3C-SiC films were obtained through a two-step route: depositing SiC films on Si substrates via laser chemical vapor deposition (LCVD), followed by wet-etching to remove the substrates. The high-power, continuous laser promotes the growth of SiC films with a high density of twin boundaries and stacking faults, along with strong interfacial bonding at grain boundaries, which suppresses crack initiation and propagation, thereby enhancing elastic deformability. The as-prepared free-standing SiC film with thickness of 200 nm withstands a maximum tensile strain of 7.35 % and a maximum bending curvature of 1 mm^-1, demonstrating excellent flexibility, which is comparable to that of the reported SiC nano-spring. Moreover, no catastrophic failure is observed after the film undergoes 1500 bending-releasing cycles, verifying its robust mechanical durability. This study lays a foundational groundwork for the development and prospective commercialization of flexible devices, which are in urgent need for large-scale, wide-bandgap inorganic flexible materials.