Solution-based straight and branched CdTe nanowires

The synthesis, characterization, and optical properties of high quality straight and branched CdTe nanowires (NWs) are described. A solution-based (solution-liquid-solid) approach is used to synthesize the NWs by employing a low melting bimetallic nanoparticle catalyst to induce one-dimensional (1D) growth. This leverages advances in the development of high quality colloidal quantum dots (QDs) with emerging techniques for manufacturing 1D nanomaterials. Resulting straight and branched CdTe NWs have diameters below twice the corresponding bulk exciton Bohr radius and, as a consequence, exhibit confinement effects in their linear absorption. Size distributions range from 15% to 20%, with NW lengths commonly exceeding 10 Am. Intrawire diameter variations are on the order of 5%. High-resolution transmission electron microscopy (TEM) images reveal that the wires are crystalline and grow exclusively along the < 111 > and < 0001 > directions of the corresponding zincblende and wurtzite phases. Branched NW morphologies include tripod, v-shape, y-shape, "merge-y", and " higher-order" structures. Preliminary optical studies of both straight and branched NWs are reported, including estimates of the absorption cross section and electrochemical band offsets. Such NWs open up avenues for further investigating the effects of size and shape on the optical/electrical properties of 1D nanomaterials and also have potential uses as active elements in photovoltaics and/or polarization sensitive photodetectors.