Figure 1

Spring constants of individual SiNWs and SiNW bundles obtained by beam theory and in situ TEM indentation. The theoretical spring constants of individual SiNWs and SiNW bundles in the six SiNWs groups were calculated using beam theory [Equation (1)] from the SiNW dimensions (L and D). At least 300 individual SiNWs were analyzed for each group. The spring constants of SiNW bundles were also determined on the basis of force–displacement curves measured by in situ TEM picoindentation (PI 95 TEM Picoindenter, Hysitron, USA). The TEM image in the inset (JEM 2010, Jeol, Japan) shows that the SiNWs easily formed bundles because of capillarity (stiction).