In₂Se₃ Nanocubes as High Current Density Cold Cathode Materials

Abstract

In the present study, we report a simple method to prepare indium­(III) selenide (In2Se3) nanocubes synthesized by laser ablation in aqueous medium. The morphological characterization carried out using field-emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) reveal that the nanocubes have an average size of 70 nm. X-ray diffraction and Raman analysis clearly imply formation of pure and crystalline In2Se3 phases only, without any impurity phases, despite laser ablation being carried out in aqueous medium. In addition, the field emission and charge carrier behavior of In2Se3 nanocubes have been investigated. The laser-ablated sample shows a cubical morphology having a 70 nm average particle size. The ultrafast transient absorption spectroscopy (UTAS) suggests the slow decay behavior of charge carriers and an increase in the trap state levels after laser ablation, in contrast to the untreated bulk sample. Surprisingly, the In2Se3 nanocubes on a carbon tape emitter exhibits superior FE properties characterized by lower values of turn-on and threshold fields as compared to In2Se3 nanowire emitters and the ability to deliver very large current density ∼2656 μA/cm2 by applying a field of 9.7 V/μm. Furthermore, the In2Se3 nanocube emitter showed very good emission stability at the pre-set value 10 μA over a duration of 5 h. The superior FE characteristics of the In2Se3 nanocube emitter is attributed to unique morphology characterized by nanometric cubes and improved electrical properties, as revealed by UTAS analysis. The observed results imply the potential of In2Se3 nanocube emitters for practical applications in vacuum nano-microelectronic devices.

A Self-Selector and Self-Rectifying Charge-Trap-Based Resistive Switching Device Using In2Se3 Thin Films

“…The presence of oxygen can be because of surface oxidation. The two intense peaks corresponding to In 3d 5/2 and In 3d 3/2 peaks match well with the previous reports, whereas the splitting in the deconvoluted Se 3d peaks indicates a higher full width at half maxima (fwhm), which is the characteristic of chalcogenides with defect nature. ,,, …”

“…In order to analyze the role of defects in the resistive switching observed in bilayer α-In 2 Se 3 , X-ray photoelectron spectroscopy (XPS) and photoluminescence (PL) spectroscopy measurements were carried out, as shown in Figure . It can be observed from Figure a,b, that the as-grown bilayer α-In 2 Se 3 films show two peaks corresponding to a binding energy of 444.5 and 452 eV for the In 3d orbitals, and 53.4 and 54.2 eV for the Se 3d orbitals, as shown in Figure c, where the observed values match well with the previous reports in literature. , Also, the peaks at 284.6 and 296.9 eV correspond to the C 1s orbitals and those at 529.8 and 531.8 eV correspond to O 1s, similar to the reports in literature . The peak corresponding to C 1s can be used as a reference to the calibration of binding energies.…”

“…The two intense peaks corresponding to In 3d 5/2 and In 3d 3/2 peaks match well with the previous reports, whereas the splitting in the deconvoluted Se 3d peaks indicates a higher full width at half maxima (fwhm), which is the characteristic of chalcogenides with defect nature. 33,34,36,37 However, the PL spectra show two peaks at 947 and 981 nm corresponding to 1.30 and 1.26 eV, respectively. 38 This indicates that there exist two in-gap states for the prepared bilayer α-In 2 Se 3 , which can act as the charge trap states leading to the observed planar switching characteristic through the Poole-Frenkel charge conduction mechanism as shown in Figure 5.…”

Characteristics of Field Emitters on the Basis of Pd-Adsorbed ZnO Nanostructures by Photochemical Method

“…Recently, many metal oxide semiconductor (MOS) materials have been developed with this aim. − Among them, ZnO is an interesting MOS material that can be used as a device of field emitter and exhibits several outstanding characteristics: (1) ZnO shows a property of direct wide band gap (3.37 eV), a large exciton binding energy (60 meV), and lattice constants of a = 3.24–3.26 Å and c = 5.13–5.43 Å at room temperature (RT). (2) ZnO is an n-type II–VI semiconductor and possesses chemical and thermal stability and a high saturated carrier drift rate.…”