Effect of the synthesis conditions on the structural, morphological and optical properties of Bi2Te2. 7Se0. 3 nanoparticles

Beside their promising utility as thermoelectric generators, Bi₂Te₃ and related compounds have several applications in electronic and optoelectronic devices. In this work, Bi₂Te_2.7Se_0.3 nanoparticles (NPs) were successfully prepared via physical vapor deposition technique at different conditions of flow rate and temperature. The x-ray diffraction patterns show that, the NPs crystallize in a rhombohedral crystal structure with preferable growth along the (015) plane. Field-emission scanning electron microscope (FE-SEM) investigation shows that the NPs size depends significantly on the synthesis conditions of flow rate and temperature where it decreases with the decrease in the former or with the increase in the later. The effect of deposition conditions on the final morphology can be interpreted through the accompanied variation in the concentration of the gaseous precursors in the hot zone. The optical properties were studied using Kubelka- Munk theory. Optical band gaps of 0.52, 0.58, 0.53 eV were determined for the samples synthesized under different conditions.