High resolution optical images

Fig.1 (a) The optical image of a NW, sliding on the Si substrate at a constant speed due to the push from a W tip. (b) Mechanical loading model for the sliding NW.

Fig.2 The optical images of a NW (a) rest on the Si substrate, (b) being pushed horizontally and bent, (c) being pushed and pressed, and (d) being pulled and pressed by the W tip 1; (e) being pushed and pressed and (f) being pulled and pressed by the W tip 2. The insets in (b)–(e) show the contact configuration between the W tip and the NW, where the arrows describe the direction of the force, F, acted on the NW from the W tip.

Fig.3 The bent NW slid on the (a) Si substrate pushed by tip 1, (b) Si substrate pushed by tip 2, and (c) SiN substrate by tip 2. (d) Frictional shear stresses on Si and SiN substrates plotted as a function of the NW length. (e) Roughness of the Si and SiN substrates measured by AFM.