Facile synthesis of ultra-small Bi2Te3 nanoparticles, nanorods and nanoplates and their morphology-dependent Raman spectroscopy

High-crystalline 0D, 1D and 2D ultra-small Bi2Te3 nanocrystals were synthesized using the pyrolysis of organometallic compound method. The Bi2Te3 nanocrystals was studied with transmission electron microscopy (TEM). Samples synthesized at 35 °C possessed a dominant morphology of 0D nanoparticles or 1D nanorods, while samples synthesized at temperatures higher than 75 °C possessed a dominant morphology of 2D nanoplates. Phonon vibrations were investigated by Raman spectroscopy. The 2D nanoplates showed similar Raman features as few-quintuple-thick Bi2Te3 layers, while the 0D and 1D nanostructures showed a blue-shifted A1g2 mode and a much stronger A1u mode. This is the first report regarding the morphology effect on the Raman-active phonon modes of Bi2Te3 nanocrystals.