Fabrication, characterization and optical properties of Au-decorated Bi(2)Se(3) nanoplatelets

Au-decorated Bi(2)Se(3) nanoplatelet heterostructures are fabricated by a two-step process of thermal CVD at 600 °C and magnetron sputtering at room-temperature. The crystal structures and binding energies of rhombohedral Bi(2)Se(3) and FCC Au are determined by XRD, HRTEM, XPS, and Raman spectroscopy. XPS and Raman spectroscopy reveal the interaction between Au and Bi(2)Se(3) by shifting in the binding energies of Au–Au, Au–Se and Bi–Se bonds and the wavenumber of A(1g)(2) and E(g)(2) modes. Au-decorated Bi(2)Se(3) nanoplatelet heterostructures are observed using FESEM, and confirmed by XPS, Raman spectroscopy, and HRTEM imaging. Their optical band gap of the Au-decorated Bi(2)Se(3) nanoplatelet heterostructures increases with Au thickness about 1.92-fold as much as that of pristine Bi(2)Se(3) (0.39 eV), owing to the Burstein-Moss effect. The optical absorptance of the Au-decorated Bi(2)Se(3) nanoplatelet heterostructures revealed increment with wavelength from 200 to 500 nm and decrement with increasing wavelength from 500 to 800 nm.