Structural, Optical, and Improved Field-Emission Properties of Tetrapod-Shaped Sn-Doped ZnO Nanostructures Synthesized via Thermal Evaporation

Abstract

High-quality tetrapod-shaped Sn-doped ZnO (T-SZO) nanostructures have been successfully synthesized via the thermal evaporation of mixed Zn and Sn powder. The effects of the Sn dopant on the morphology, microstructure, optical, and field-emission (FE) properties of T-SZO were investigated. It was found that the growth direction of the legs of T-SZO is parallel to the [0001] crystal c-axis direction and that the incorporation of Sn in the ZnO matrix increases the aspect ratio of the tetrapods, leads to blue shift in the UV region, and considerably improves the FE performance. The results also show that tetrapod cathodes with around a 0.84 atom % Sn dosage have the best FE properties, with a turn-on field of 1.95 V/μm, a current density of 950 μA/cm2 at a field of 4.5 V/μm, and a field-enhancement factor as high as 9556.

Unique visible-light-assisted field emission of tetrapod-shaped ZnO/reduced graphene-oxide core/coating nanocomposites

“…Figure 2(c) presents high-resolution scanning information on the elemental Zn in pure T-ZnO and in T-ZnO/rGO nanocomposites. The binding energies of the Zn 2p 3/2 and the Zn 2p 1/2 peaks for pure T-ZnO are located at 1022.05 and 1045.20 eV, respectively, exhibiting an energy difference of 23.15 eV, which is in reasonable agreement with the standard XPS spectrum of ZnO5. The high-resolution XPS spectrum of Zn for the T-ZnO/rGO nanocomposites shows a doublet, corresponding to the Zn 2p 3/2 and the Zn 2p 1/2 orbitals, at 1022.05 eV and 1045.20 eV, respectively.…”

“…The peak at 530.28 eV is attributed to oxidized metal ions (O−Zn 2+ ). The binding energy component at 532.32 eV might correspond to the existence of a weakly-bound oxygen species on the surface of the T-ZnO5. The O 1 s signal for the T-ZnO/rGO nanocomposites can be fitted by using three nearly Gaussian components centered at 530.28, 531.54, and 532.98 eV, respectively.…”

“…Especially, zinc oxide (ZnO) nanostructures are high-performance field-emission sources due to their high thermal and mechanical stability, high oxidation resistance in harsh environments, low work functions and easy preparation. We have demonstrated that ZnO nanostructures, including nanorods, tetrapod-shaped ZnO (T-ZnO), nanoparticles, and ZnO film4567, exhibit excellent field-emission properties. However, their relatively low conductivity and low aspect ratio have limited their emission current density and have hindered their practical applications in efficient field-emission devices.…”

Enhanced field emission from ZnO nanowire arrays utilizing MgO buffer between seed layer and silicon substrate

“…Meanwhile, the alignment is an important factor for field emission (FE) properties [13]. All kinds of fabrication methods such as vapor transfer process [14], metal organic chemical vapor deposition [15], thermal evaporation [16] and hydrothermal synthesis [17] have been utilized to prepare 1D ZnO nanostructures.…”

Synthesis of CdS multipods from cadmium xanthate in ethylenediamine solution

“…In particular, when used as field emitters, the four legs yield more efficient electron emission and there is always one leg vertically oriented to the anode, enabling a lower turn-on field. Further improvement of field emission performance can be achieved using the tetrapodshaped Sn-doped ZnO (T-SZO) nanostructures, which offer not only the geometric factors but also higher conductivity, which could be expected to result in a lower turn-on field and higher emission current (Zhou et al, 2013). The CdS-CdSe tetrapod quantum dots, when incorporated into polymer matrices via electrospinning, may be used as an in situ luminescent stress probe for monitoring the mechanical properties of polymer fibers (Raja et al, 2013).…”