Surface Roughness Assisted Growth of Vertically Oriented Ferroelectric SbSI Nanorods

We report the catalyst-free synthesis of arrays of c-axis oriented antimony sulfoiodide nanorods on anodic aluminum oxide (AAO) substrates by vapor phase deposition. The surface roughness of the AAO substrates played a decisive role in the orientation control of the SbSI nanorods produced. The as-grown SbSI nanorods were single-crystalline and <001> oriented, as revealed from the X-ray diffraction and transmission electron microscopy analysis. Switching spectroscopy-piezoresponse force microscopy experiments demonstrated, for the first time, the presence of switchable ferroelectricity and piezoelectricity in individual SbSI nanorods. Ferroelectric switching in the SbSI nanorods was found to occur via a 180 domain reversal, because of the preferred orientation of the nanorods along their polar c-axis.