2003 Fiscal Year Final Research Report Summary
Evaluation of Mechanical Properties for Nanometric Silicon Wire Used for Single Electron
Grant-in-Aid for Scientific Research (B)
|Allocation Type||Single-year Grants |
Materials/Mechanics of materials
|Research Institution||Ritsumeikan University |
ISONO Yoshitada Ritsumeikan Univ., Fac.Science and Engineering, Professor -> 立命館大学, 理工学部, 助教授 (20257819)
|Project Period (FY)
2001 – 2003
|Keywords||Silicon nanowire / Bending test / Tensile test / Atomic force microscope / Electrostatic actuator / Size effect|
This research focuses on revealing specimen size and temperature effects on mechanical properties of nanometric single crystal silicon (SCS) wires used for single electron devices. Mechanical properties of the nanometric SCS wires were characterized by bending tests with an atomic force microscope (AFM). The fixed-fixed SCS wires with widths from 200 nm to 800 nm and a thickness of 255 nm were fabricated on a silicon diaphragm by means of field-enhanced anodization with AFM and anisotropic wet etching. The AFM bending tests of the SCS wires were carried out at temperatures ranging from 295 K to 573 K in high vacuum. The tensile tesiting device including an electrostatic actuator and nanometric SCS wire was also designed.
The nanometric SCS wires fractured in a brittle manner at room temperature, whereas they deformed plastically above 373 K. Young's modulus of the wires in the <110> direction on the (111) surface at temperature ranging from 295 K to 573 K averaged from 170 GPa to 159 GP
a, respectively, but had no specimen size effect. However, the specimen size produced a large effect on the fracture strength since the fracture strength of the 200 nm-wide wires ranged from 17.8 GPa to 15.9 GPa, which were 1.5 times larger than that of the 800 nm-wide wires.
Plastic flow of the nanometric SCS wires appeared in force-displacement curves at 373 K, which was caused by high shear stress acting on the wires. Slip lines comprised of edge dislocations responsible for the plastic flow was observed by AFM and SEM techniques. The slip line density of the nanometric wires was 100 times larger than that of the micrometer scale specimen, which meant the specimen size had a large influence on the plastic deformation behavior. The edge dislocation model newly proposed in this research was able to rationalize that the specimen size effect on the plastic deformation behavior at elevated temperature was determined by the correlation between the specimen size and the activation Gibbs free energy.
Finally, the electrostatic actuator on the tensile testing device, developed here, gave a useful performance in the nanoscale tensile testing. Less
Research Products (4 results)