Light and Force Reveal Hardening of Materials Under Illumination

Researchers from Nagoya University and the Technical University of Darmstadt developed a method to quantitatively study the effect of light on nanoscale mechanical properties of thin-wafer semiconductors or any other crystalline material. The method, which the researchers characterized as “photoindentation,” uses a tiny, pointed probe to indent the material while a light source illuminates the material in a controlled environment, in which the depth and rate at which the probe indents the surface can be measured. The probe creates dislocations, or slippages of crystal planes, near the material surface. The researchers observed the effect of light at a range of wavelengths on dislocation nucleation (the birth of new...