Pt nanoparticles utilized as efficient ultraviolet plasmons for enhancing whispering gallery mode lasing of a ZnO microwire via Ga-incorporation

Exciton-polariton light-emitting diode based on a single ZnO superlattice microwire heterojunction with performance enhanced by Rh nanostructures

One-dimensional (1D) wirelike superlattice micro/nanostructures have received considerable attention for potential applications due to their versatility and capability for modulating optical and electrical characteristics. In this study, 1D superlattice microwires (MWs), which are made of undoped ZnO and Ga-doped ZnO with periodic and alternating crystalline layers (ZnO/ZnO:Ga), were synthesized individually. Under optical excitation, a series of resonance peaks in the photoluminescence spectrum can be ascribed to polariton emission, which originates from the coupling interaction of the 1D photonic crystal and confined excitons along the wire direction. Using a p-type GaN layer as the hole transport layer, a kind of waveguide light source based on an individual ZnO/ZnO:Ga superlattice MW was proposed and constructed. By analysing the spatially resolved electroluminescence spectra, the observed multipeak was ascribed to exciton-polariton emission with a vacuum Rabi splitting of about 275 meV. Cladding with Rh nanostructures gives rise to appropriate ultraviolet plasmons, and the Rabi splitting energy of our device was enhanced up to 413 meV. The exciton-polariton properties were further examined using angle-resolved electroluminescence measurements. Therefore, individual superlattice MWs can act as optical microresonators to achieve photon-exciton coupling with a large Rabi splitting energy. The experimental results indicate that an individual ZnO/ZnO:Ga superlattice MW can be generally used in developing exciton-polariton luminescence/lasing light sources, particularly for constructing low-threshold/thresholdless lasers toward pragmatic applications.

Electrically driven single microwire-based single-mode microlaser

Engineering the lasing-mode oscillations effectively within a laser cavity is a relatively updated attentive study and perplexing issue in the field of laser physics and applications. Herein, we report a realization of electrically driven single-mode microlaser, which is composed of gallium incorporated zinc oxide microwire (ZnO:Ga MW) with platinum nanoparticles (PtNPs, d ~ 130 nm) covering, a magnesium oxide (MgO) nanofilm, a Pt nanofilm, and a p-type GaN substrate. The laser cavity modes could resonate following the whispering-gallery mode (WGM) among the six side surfaces by total internal reflection, and the single-mode lasing wavelength is centered at 390.5 nm with a linewidth of about 0.18 nm. The cavity quality factor Q is evaluated to about 2169. In the laser structure, the usage of Pt and MgO buffer layers can be utilized to engineer the band alignment of ZnO:Ga/GaN heterojunction, optimize the p-n junction quality and increase the current injection. Thus, the well-designed device structure can seamlessly unite the electron-hole recombination region, the gain medium, and optical microresonator into the PtNPs@ZnO:Ga wire perfectly. Such a single MW microlaser is essentially single-mode regardless of the gain spectral bandwidth. To study the single-mode operation, PtNPs working as superabsorber can engineering the multimode lasing actions of ZnO:Ga MWs even if their dimensions are typically much larger than that of lasing wavelength. Our findings can provide a straightforward and effective scheme to develop single-mode microlaser devices based on one-dimensional wire semiconductors.

Plasmon-enabled spectrally narrow ultraviolet luminescence device using Pt nanoparticles covered one microwire-based heterojunction

Owing to great luminescent monochromaticity, high stability, and independent of automatic color filter, low dimensional ultraviolet light-emitting diodes (LEDs) via the hyperpure narrow band have attracted considerable interest for fabricating miniatured display equipments, solid state lighting sources, and other ultraviolet photoelectrical devices. In this study, a near-ultraviolet LED composed of one Ga-doped ZnO microwire (ZnO:Ga MW) and p-GaN layer was fabricated. The diode can exhibit bright electroluminescence (EL) peaking at 400.0 nm, with a line width of approximately 35 nm. Interestingly, by introducing platinum nanoparticles (PtNPs), we achieved an ultraviolet plasmonic response; an improved EL, including significantly enhanced light output; an observed blueshift of main EL peaks of 377.0 nm; and a reduction of line width narrowing to 10 nm. Working as a powerful scalpel, the decoration of PtNPs can be employed to tailor the spectral line profiles of the ultraviolet EL performances. Also, a rational physical model was built up, which could help us study the carrier transportation, recombination of electrons and holes, and dynamic procedure of luminescence. This method offers a simple and feasible way, without complicated fabricating technology such as an added insulating layer or core shell structure, to realize hyperpure ultraviolet LED. Therefore, the proposed engineering of energy band alignment by introducing PtNPs can be employed to build up high performance, high spectral purity luminescent devices in the short wavelengths.