Achieving micron-scale plasticity and theoretical strength in Silicon

• Published in: Nature communications Vol. 11; no. 1; pp. 2681 - 10
• Main Authors: Chen, Ming, Pethö, Laszlo, Sologubenko, Alla S., Ma, Huan, Michler, Johann, Spolenak, Ralph, Wheeler, Jeffrey M.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 29.05.2020; Nature Publishing Group; Nature Portfolio
• Subjects: 142/126; 147/135; 147/137; 147/143; 639/301/1005; 639/301/357/537; 639/301/357/551; Ambient temperature; Deformation; Deformation mechanisms; Diamonds; Elastic limit; Fabrication; Humanities and Social Sciences; Ion beams; multidisciplinary; Plastic deformation; Plastic properties; Plasticity; Science; Science (multidisciplinary); Shear strength; Silicon; Size effects; Strain; Structure-function relationships; Surface properties
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-020-16384-5

As the backbone material of the information age, silicon is extensively used as a functional semiconductor and structural material in microelectronics and microsystems. At ambient temperature, the brittleness of Si limits its mechanical application in devices. Here, we demonstrate that Si processed by modern lithography procedures exhibits an ultrahigh elastic strain limit, near ideal strength (shear strength ~4 GPa) and plastic deformation at the micron-scale, one order of magnitude larger than samples made using focused ion beams, due to superior surface quality. This extended elastic regime enables enhanced functional properties by allowing higher elastic strains to modify the band structure. Further, the micron-scale plasticity of Si allows the investigation of the intrinsic size effects and dislocation behavior in diamond-structured materials. This reveals a transition in deformation mechanisms from full to partial dislocations upon increasing specimen size at ambient temperature. This study demonstrates a surface engineering pathway for fabrication of more robust Si-based structures. Silicon is thought to be brittle, which limits its mechanical application in devices. Here, the authors lithographically fabricate silicon and show its superior surface quality leads to near ideal strength and micron-scale plasticity.