| ZnS is an important kind of direct wide band gap II-VI semiconductor materials with band gap of 3.7eV at room temperature. Due to its excellent optical and electrical properties, ZnS has important use in the electronic, chemical, aerospace, defense and other fields. ZnS nanomaterial has been a hot research topic in the industry, such as the control of the size, morphology and structure, the element doping and the analysis of the influence on its performance caused by these aspects.In this paper, we successfully prepared ZnS nanomaterials with different size and morphology, also administered the doping elements in ZnS nanostructures. In addition, we synthesized ZnS:Al one-dimensional nanostructures. Finally, the performance of the various aspects of the above-mentioned material samples were tested and analyzed. The specific content is as follows.Firstly, syntheses of ZnS nanoparticles and nanorods with different size have been achieved by the hydrothermal method. SEM, TEM, HRTEM and XRD results showed that ZnS nanoparticles are cubic structure and the size of them are about 5-30 nm. In contrast, ZnS nanorods have a wurtzite crystal structure, which grows along the [0001] direction. The length of the ZnS nanorods are 100-200 nm approximately, and the diameter is about tens of nanometers. Both in nanoparticles and nanorods samples we all observed the random distribution of stacking faults (SFs) and twin crystal structure. Based on the research of the Raman spectrum analysis, we obtained some interesting phenomenon.The first-order longitudinal optical phonon mode exhibits a blueshift of 6 cm-1 when the particle size increases from 5 to 15 nm, but there is no shift in the range of 15-30 nm because of quantum confinement and microdefects.Compared with ZnS nanoparticles, due to the phonon confinement effect, the SO and LO of ZnS nanorods have a blueshift of 2-4 cm-1 and 2-8 cm-1, respectively.Secondly, through hydrothermal method, we prepared the samples of Er-doped ZnS particles. XDR analysis showed that all of the samples have cubic phase structure with a good crystallinity. Calculated by Shaler Formula, we found when the concentration of the Er increased, the size of Er-doped particles presents a special variation trend, which is first decrease and then increase, then decrease. We believe this change relationship caused by the synergy of two factors. One is that the Er atoms with larger size expand the lattice, the other one is that Er3+ ions can strengthen the interaction between the anion and cation, which lead to the lattice contraction. SEM analysis showed that all samples are spherical particles, and have a uniform size. From the ultraviolet absorption spectrum, we not only got absorption peak of ZnS, also found the absorption peak of Er3+ion, which proves that ZnS samples are doped with Er3+ ions. In addition, with the increase of Er doped concentration, the absorption peak of Er3+ strengthened. Through PL spectrum analysis, we got two luminescence peaks, located at 520 nm and 556 nm, respectively caused by the surface state and the energy level transition of Er3+. From the Raman spectra, we observed 1LO,1TO,2LO,2TO and some process of phonon, and the red shift phenomenon related to the lattice strain, also found that as the sample size is reduced, exciton phonon coupling strength enhanced. Paramagnetic resonance analysis showed that all the samples are in the hyperfine structure, further confirmed the Er3+ ions doped to ZnS.Thirdly, Al-doped ZnS one-dimensional nano material were ssuccessfully grow on Au-coated Si substrates by a chemical vapor transport method. In the growth process, the distance between raw materials and substrates has an important impact on the morphology of material. SEM showed that samples have two main types of morphology. XRD showed that the structure of the material is a mixture of zinc-blende crystal and wurtzite crystal structure. Raman spectroscopy analysis showed that the proportion of SO peak of the samples with "burr", and the overall strength of Raman scattering are strengthened. This all comes down with the special structure, large specific surface area and surface state. |
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