Iodization of antimony thin films:: XRD, SEM and optical studies of nanostructured SbI3

Antimony films of thicknesses of 25, 40 and 80 nm deposited using thermal evaporation technique were annealed at 200 degrees C for 6 h. Programmed iodization was carried out at room temperature for periods ranging from 5 min to 9 h on both as-deposited and annealed films. X-ray diffraction studies on iodized films reveal that Antimony tri-iodide nanoparticles grow only on annealed antimony films. Surface morphology as revealed through SEM consists of antimony and antimony tri-iodide nanoparticles are 25 nut and 1 mu m, respectively. Optical absorption of Sb and SbI3 nanoparticles carried out at room temperature. As-deposited antimony film of thickness 25nm exhibits a sharp rise in the absorption near ultraviolet region while post-deposition annealed films were characterized by red shifted absorption. Interestingly 45 nm thick Sb films exhibit a broad volume plasmon resonance peak around 500 nm with a width of 200 nm. Progressive iodization of 25 nm thick film reveals two absorption bands at 381.7 nm (A(2)) and 458.3 nm (B-3) with photon energies 3.25 and 2.70 eV, respectively, due to the development of SbI3 valence band structure. Last members of hydrogen-like series of absorption levels A(2) and B-3 due to halogen doublet (3/2, 1/2) splitting have been observed at room temperature. (c) 2007 Published by Elsevier Ltd.