Growth of quasi-1 dimensional (Bi1-xSbx)(2)S-3 nanowires on fluorine-doped tin oxide glass substrate by vapor transport

摘要

(Bi1-xSbx)(2)S-3 solid solution nanowires (0 <= x <= 0.73) are grown on fluorine-doped tin oxide (FTO) glass via physical vapor transport. The compositions were controlled by varying the Sb2S3 source temperature (300 degrees C-453 degrees C) by changing the upstream locations of the Sb2S3 source in the furnace while keeping the Bi2S3 source at the center of the furnace (497 degrees C). Defect-free nanowires with phase-pure orthorhombic and quasi-1 dimensional crystal structures were grown under a modified vapor-solid mechanism affected by FTO at initial growth stage. The aspect ratios of the nanowires reached the minimum at composition x similar to 0.6. As the Sb2S3 source approached the Bi2S3 source, x increased owing to the increase in the Sb2S3 source temperature. x/(1-x), which is proportional to the evaporation flux of the Sb2S3 source, could be well-fitted with a thermally activated equation with an apparent activation energy (105 kJ mol(-1)). However, at the distance between the Sb2S3 and Bi2S3 sources, with the Sb2S3 source at temperatures higher than 410 degrees C, the compositions reduced despite the increased Sb2S3 evaporation flux. Such retrograde behavior was confirmed by high-resolution transmission electron microscopy, x-ray diffraction, and micro-Raman studies. This retrograde behavior is ascribed to the loss due to the reaction of gaseous Sb species with the Bi2S3 source.