Structure and Properties of ZnSxSe1-x Alloy Nanostructures Embedded in Anodic Alumina Membrane.
A.I. Chukavin, R.G. Valeev, A.N. Beltiukov, Ya.V. Zubavichus, A.L. Trigub, V.V. Kriventsov. Structure and properties of ZnSxSe1-x alloy nanostructures embedded in anodic alumina membrane.
The International Conference "Synchrotron and Free electron laser Radiation: generation and application" (SFR-2016) – Novosibirsk, 04 - 07 Jul 2016.
ZnSxSe1-x alloys, as an important member of II–VI ternary semiconductors, have attracted significant interest until now due to their variable band gap, spanning from 2.7 eV to 3.67 eV, which makes them appropriate for developing short wave length LEDs and laser diodes operating entirely in the blue–violet region. Recently, the ZnSxSe1-x alloy nanostructures were synthesized by a variety of methods such as chemical vapor deposition (CVD) and metal organic chemical vapor deposition [2-4]. The electronic structure and band gap of ZnSxSe1-x were also discussed. The design of ZnS ySe1-y/GaAs (001) heterostructures and their dynamical X-ray diffraction were reported [6,7]. It is worthy to note that the 1D ZnSxSe1-x-based ZnO/ZnSxSe1-x core/shell nanowire arrays, ZnO/ZnSxSe1-x/ZnSe double-shelled heterostructure and ZnS/ZnSxSe1-x nano-heterostructures have also been synthesized by chemical vapor deposition method or magnetic force assistant growth technique, which exhibit efficient visible light absorption, enhanced photoelectrochemical performance and integrating emission property, respectively . However, the data on the optical absorption and photoluminescence spectra yielded different results for the ternary compounds produced by different methods, and understanding of the physical mechanism leading to this controversy is still not achieved. The semiconductor nanostructures in dielectric matrixes are of current interest due to absorption and luminescent properties improved in comparison to thin films of materials. In nanocrystals, the surface-to-volume ratio is considerably large, therefore there is a high contribution of surface in the luminescence properties. The unsaturated bonds on the surface create band-gap states that can easily capture the excited electrons and holes and relax the energy in non-radiative ways . In addition, matrix isolation allows to protect nanostructures from external influences. In this work we for the first time have successfully synthesized alloyed ZnSxSe1–x nanowires embedded in a anodic alumina membrane via thermal evaporation of the mixture of ZnS and ZnSe powders. Various compositions can be easily obtained by changing the mole ratio of ZnS to ZnSe in a source material. The X-ray diffraction patterns show that the lattice structure of these nanostructures is cubic ZnSe-like, as S atoms replace Se and nanostructures compositions correlate with their initial S/Se ratio. Chemical composition was controlled by XPS method. Optical absorption spectra show that band gaps of the alloy cover the entire range from 2.7 eV to 3.67 eV by changing the component ratio, in agreement with literature. The study of the local atomic structure was carried out via EXAFS method. The set of structural parameters, namely the interatomic distances and corresponded coordination numbers, were established. All possible structural models were discussed in detail. Additionally ZnSxSe1–x samples were characterized by the TEM, EDX and XPS methods. The data obtained by all the methods are in a good agreement.