Growth direction and morphology of ZnO nanobelts revealed by combining<i>in situ</i>atomic force microscopy and polarized Raman spectroscopy

Control over the morphology and structure of nanostructures is essential for their technological applications, since their physical properties depend significantly on their dimensions, crystallographic structure, and growth direction. A combination of polarized Raman (PR) spectroscopy and atomic force microscopy (AFM) is used to characterize the growth direction, the presence of point defects and the morphology of individual ZnO nanobelts. PR-AFM data reveal two growth modes during the synthesis of ZnO nanobelts by physical vapor deposition. In the thermodynamics-controlled growth mode, nanobelts grow along a direction close to [0001], their morphology is growth-direction dependent, and they exhibit no point defects. In the kinetics-controlled growth mode, nanobelts grow along directions almost perpendicular to [0001], and they exhibit point defects.