DGIST and Yonsei use third-harmonic microscopy to read strain in wrinkled 15 nm silicon films

Korean researchers showed how light response changes in wrinkled ultrathin silicon and proposed a non-destructive way to read local strain, relevant to flexible electronic and optical devices.

DGIST and Yonsei University researchers in South Korea have developed a way to analyze strain in wrinkled ultrathin silicon, fnnews.com reports. Yonsei made the wrinkled silicon nanomembranes, and the DGIST group studied their optical response. fnnews.com

DGIST combined third-harmonic generation microscopy, which yields light at three times the input frequency, with first-principles quantum calculations. Infrared light at 1040 nm produced a resonance with electrons in silicon and an ultraviolet signal near 346 nm. The ratio of signal intensity between polarization directions differed at wrinkle crests and troughs, depending on strain.

In membranes about 15 nm thick, changes in electronic structure and the 3D wrinkle shape alter the local light distribution and affect the signal. The study was published in Nano Letters.