Crystallography of Novel T-Shaped ZnS Nanostructures and Their Cathodoluminescence

Abstract

Novel T-shaped ZnS nanostructures are synthesized through simple ZnS powder evaporation. High-resolution transmission electron microscopy (HRTEM) and electron diffraction (ED) analyses demonstrate that the structures are composed of a bicrystalline base sheet (010)/(102)/(010)* and a protruding thick wire. The two structural domains are connected along the twin boundary on the (102) plane. Cathodoluminescence measurements show that the T-shaped ZnS nanostructures exhibit three clear emission zones in the ranges of 380−550 nm, 550−760 nm, and 760−1000 nm, whereas the band gap emission is not observed. Finally, the related optical emission mechanism is discussed based on the TEM results.

Self-assembled highly symmetrical ZnS nanostructures and their cathodoluminescence

“…2a) and one can find that all the atoms exhibit the same atomic stacking sequence as the above two areas. Based on the detailed microstructure analysis, it can be concluded that the as-grown ZnS nanostructures were single crystal and no structural defect such as twin or stacking fault was found [5]. In addition, the crystalline characteristic of the ZnS nanostructures could be further demonstrated by the regularly arranged ED spots.…”

“…Thus, it can be used to fabricate some highly sensitive ultraviolet optoelectronic devices such as ultraviolet photodetector and H 2 sensor [7,15]. However, most of the ZnS crystals, either bulk or nanostructures, exhibit strong green emissions rather than the intrinsic band-gap ultraviolet emission due to the existence of large amount of structural defects such as twin or stacking fault [5]. In addition, the impurity contamination in ZnS lattice such as O element can also lead to the shift of emission wavelength towards the visible range.…”

“…ZnS nanostructures with high structural symmetry were directly synthesized in a horizontal electrical resistance furnace through a feasible thermal evaporation process, as reported elsewhere [5]. The typical procedure for ZnS nanostructure growth can be simply described as follows: high-purity ZnS powders of micro-size (Sinopharm Chemical Reagent Co., Ltd.; purity 99.99%) loaded into an Al 2 O 3 boat were placed at the center of a quartztube (140 cm in length and 40 mm in outer diameter) and then a piece of Si substrate ( deposition of ZnS nanostructures, with a distance of $10 cm from the center.…”

“…Compared with the formation of conventional nanostructures, the nucleation of three-dimensional (3D) complex nanostructures and their subsequent growth may rely on a selfassembly process [3,4]. In addition, some unexpected phenomena and interesting properties may also be found in these complex nanostructures and thus some specific applications based on these unconventional nanostructures in the field of optics, magnetism and electronics can be explored [5].…”

“…For instance, low-dimensional ZnS nanostructures such as nanowires, nanobelts and nanotubes fabricated from either physical evaporation or chemical routines have been widely reported and their applications as ultraviolet photodetectors and luminescent phosphors have been realized [7][8][9]. Unlike the normal synthesis of low-dimensional ZnS nanostructures, unconventional 3D ZnS nanostructures with peculiar morphologies and shapes can often be formed through a self-assembly process that possesses unexpected properties [3,5].…”