Cai Xing-Min

Composition-Dependent Characterization of Sb2Te3 Thin Films Prepared by Ion Beam Sputtering Deposition

The optimization of ion beam sputtering deposition process for Sb2Te3 thin films deposited on BK7 glass substrates is reported. The influence of composition ratio on the thermoelectric properties is investigated. X-ray diffraction shows that the major diffraction peaks of the films match with those of Sb2Te3. Hall effect and Seebeck coefficient measurement reveal that all the samples are of p-type. The Sb2Te3 thin films exhibit the Seebeck coefficient of 190 μVk−1 and the electrical conductivity of 1.1 × 103 Scm−1 when the atomic ratio of Sb to Te is 0.65. Carrier concentration and motility of the films increase with the increasing atomic ratio of Sb to Te. The Sb2Te3, film with a maximum power factor of 2.26 × 10−3 Wm−1K−2 is achieved when annealed at 400° C. Raman measurement shows that the main peaks are at about 120 cm−1, 252 cm−1 and 450 cm−1, in agreement with those of V-VI compound semiconductors.

Growth and Characterization of CIS Thin Films Prepared by Ion Beam Sputtering Deposition

Copper indium diselenide (CuInSe2) thin films were prepared by ion beam sputtering Cu, In and Se targets continuously on BK7 glass substrates and the three-layer film was then annealed in the same vacuum chamber. X-ray diffraction shows that the CuInSe2 thin films have a single chalcopyrite structure with preferential (112) orientation. Scanning electron microscopy reveals that the CIS thin films consist of uniform and densely packed grain clusters. Energy dispersive x-ray spectroscopy demonstrates that the elemental composition of CIS films approaches the stochiometric composition ratios of 1:1:2. Raman measurement shows that the main peak is at about 174 cm−1 and this peak is identified as the A1 vibrational mode from chalcopyrite ordered CuInSe2. Optical transmission and absorption spectroscopy measurement reveal an energy band gap of about 1.05eV and an absorption coefficient of 105 cm−1. The film resistivity is about 0.01 Ωcm.