Highly Sensitive Detection of the Lattice Distortion in Single Bent ZnO Nanowires by Second-Harmonic Generation Microscopy

We demonstrate a highly sensitive detection of the lattice distortion in single bent ZnO nanowires (NWs) by second-harmonic generation (SHG) microscopy. As the curvature of the single bent ZnO NW increases to 21 mm –1 (<4% bending distortion), it shows a significant decrease (∼70%) in the SHG intensity ratio between perpendicular and parallel excitation polarization with respect to c -axis of ZnO NWs. A high detection sensitivity of 10 –3 nm on the bending distortion is obtained in our experiment. Importantly, the extraordinary nonaxisymmetrical SHG polarimetric patterns are also observed, indicating the twisting distortion around c -axis of ZnO NWs. Thus, SHG microscopy provides a sensitive all-optical and noninvasive method for in situ detecting the lattice distortion under various circumstances.