Effect of crystallinity-damage recovery on mechanical properties of Ga-implanted sub-100nm Si nanowires

摘要

In this paper, the effect of high-vacuum annealing with crystallinity-damage recovery on mechanical characteristics of Ga-implanted Si nanowires (NWs) fabricated by focused ion beam (FIB) is described. We have specially designed and developed “Beetle-like” tensile test device, presented for the first time, enables us to directly tension 10 ∼ 200 nm-wide Si NWs with high precision. Also, we have established the test technique to perform the tensile testing with in-situ observation in a field-emission scanning electron microscope (FE-SEM), which has the displacement measurement system by a digital image correlation using SEM image. In addition, “Cassette-type” sample preparation technique for Si NWs made from silicon on nothing (SON) membrane is contrived for annealing at 700 °C in high-vacuum. After the annealing, Si NWs were sampled to the device without FIB observation, and tensile tested. The Young's modulus gradually recovers with increasing annealing time, whereas the strength drops first at 10 sec annealing and then slightly increases with annealing time. The difference in recovering process between these characteristics is discussed from the viewpoint of crystallinity recovery and Ga-nanocluster generation & annihilation.