From nano-twinning to the glide of full dislocations: Micropillar compression tests on silicon up to 900 °C

This work investigates the micromechanical deformation behavior of monocrystalline [1 0 0]-oriented silicon micropillars at high temperatures, focusing on the range between 500 °C and 900 °C. A significant reduction in material strength is observed with increasing temperature. Tests at varying strain rates indicate a change in the deformation mechanism with increasing temperature. Correlative post-deformation TEM characterization was employed to detail the microstructural origins. Indeed, a gradual transition was unveiled. While plasticity is almost exclusively dominated by twinning through the glide of leading Shockley partial dislocations at 500 °C, a gradual transition towards full dislocations is observed with increasing temperature. While this transition has been previously observed in macroscopic samples, this study further delves into the strain rate-dependent high-temperature plasticity of silicon at small scales, reporting valuable mechanistic data highly relevant for miniaturized silicon structures in modern information technology.