WoS İndeksli Yayınlar Koleksiyonu / WoS Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7150
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Article Citation - WoS: 22Citation - Scopus: 23Effect of Heat Treating Metallic Constituents on the Properties of Cu2znsnse4 Thin Films Formed by a Two-Stage Process(Elsevier Ltd., 2017) Olgar, Mehmet Ali; Başol, B. M.; Aygün, Gülnur; Özyüzer, Lütfi; Aygün, Gülnur; Özyüzer, Lütfi; Bacaksız, Emin; 04.05. Department of Pyhsics; 04. Faculty of Science; 01. Izmir Institute of TechnologyIn this study Cu2ZnSnSe4 (CZTSe) thin films were grown by a two-stage process that involved sputter deposition of a Cu/Sn/Zn/Cu metallic stack, annealing the stack at various temperatures for 30 min, evaporation of a Se cap over the metallic stack thus forming a precursor layer, and subjecting the precursor layer to a final high temperature reaction step at 550 °C. Different samples were prepared with annealing temperatures of the metallic stacks ranging from 200 °C to 350 °C. The results showed that heat treatment of the metallic stacks did not cause much change in their morphology and elemental composition, however their phase content changed noticeably when the anneal temperature was raised to 250 °C. Specifically, while the metallic films were dominated by CuSn and Cu5Zn8 phases at low temperatures, the dominant phase shifted to Cu6Sn5 at the annealing temperature of 250 °C and higher. Also formation of a distinct Cu3Zn2 phase was observed upon annealing at temperatures at or above 250 °C. After reaction with Se, the CZTSe layer obtained from the metallic film, which was annealed at 250 °C was found to be the best n terms of its composition, crystalline quality and purity, although it contained a small amount of CuSe. The other layers were found to contain small amounts of other secondary phases such as SnSe, CuSe2, ZnSe and Cu2SnSe3. SEM micrographs showed denser structure for CZTSe layers grown from metallic films annealed at or above 250 °C. Optical band gap, resistivity and carrier concentration of the best quality CZTSe film were found to be about 0.87 eV, 2 Ω-cm and 4 × 1017 cm− 3, respectively.Article Citation - WoS: 36Citation - Scopus: 37Influence of Copper Composition and Reaction Temperature on the Properties of Cztse Thin Films(Elsevier Ltd., 2016) Olgar, Mehmet Ali; Atasoy, Y.; Özyüzer, Lütfi; Aygün, Gülnur; Özyüzer, Lütfi; Bacaksız, Emin; 04.05. Department of Pyhsics; 04. Faculty of Science; 01. Izmir Institute of TechnologyIn this study Cu2ZnSnSe4 (CZTSe) compound layers were grown using a two-stage technique that involved deposition of metallic precursors (Cu, Zn, and Sn) and Se in the first stage, followed by reaction of all the species at temperatures between 525 °C and 600 °C, during the second stage of the process. Two sets of samples, one with Cu-poor, Zn-rich and the other with Cu-rich, Zn-rich compositions, were prepared and their structural, optical and electrical properties were measured. XRD analyses showed the characteristic peaks of CZTSe regardless of the Cu content and the processing temperature. However, for samples reacted at temperatures of 575 °C and 600 °C a Cu2-xSe secondary phase separation was detected for all films suggesting that the reaction temperatures should be limited to values below 575 °C in a two-stage process such as ours. Excessive Sn loss was also present in samples processed at the highest temperatures. Raman scattering measurements confirmed formation of the CZTSe kesterite structure, and also indicated a small ZnSe phase, which could not be detected by XRD. Scanning electron micrographs demonstrated dense film structure with the Cu-rich films having smoother morphology. Optical characterization showed that increasing the Cu content in the compound layers caused a reduction in the optical band gap values due to increased interaction between the Cu-3d orbital electrons and the Se-4p orbital electrons. Electrical measurements showed that the carrier concentration increased with Cu content.