Enhanced internal quantum efficiency in non-polar ZnO/Zn0.81Mg0.19O multiple quantum wells by Pt surface plasmons coupling

High performance lasing in a single ZnO microwire using Rh nanocubes

High-purity and size-controlled Rh nanocubes (RhNCs) with plasmonic responses in the ultraviolet spectrum range were synthesized; the ultraviolet plasmonic features of RhNCs have potential applications in wide bandgap semiconductors and optoelectronic devices because of their optical tunability and stability, as well as the compatibility with neighboring semiconductor micro/nanostructures. In this work, by incorporating RhNCs, the near-band-edge emission of a single ZnO microwire is considerably enhanced. When optically pumped by a fs pulsed laser at room temperature, RhNCs-plasmon enhanced high-performance whispering gallery mode (WGM) lasing characteristics, including lower lasing threshold, higher Q-factor, and lasing output enhancement, can be achieved from a single ZnO microwire covered by RhNCs. To further probe the modulation effect of RhNCs plasmons on the lasing characteristics of the ZnO microwires, time-resolved photoluminescence (TRPL) and electromagnetic simulation analyses were also performed. Based on our results, it can be concluded that size-controlled RhNCs with ultraviolet energy-tunable plasmons have the potential for use in optoelectronic devices requiring stable and high-performance in the short wavelength spectrum band owing to their unique ultraviolet plasmonic features.

Employing rhodium tripod stars for ultraviolet plasmon enhanced Fabry–Perot mode lasing

Rhodium tripod stars serving as ultraviolet plasmons can provide a highly competitive platform to achieve high-performance Fabry–Perot lasing of quadrilateral ZnO microwires.

Photoluminescence enhancement in non-polar ZnO films through metallodielectric mediated Al surface plasmons

Non-polar ZnO thin films are grown on m-plane sapphire substrates by plasma-assisted molecular beam epitaxy. Emission enhancement from non-polar ZnO thin films coated with Al/AlO_x has been studied by photoluminescence spectroscopy. AlO_x has been used to mediate the surface plasmon (SP) energy of Al nanoparticles. Taking advantage of the resonant coupling between the UV emission of non-polar ZnO film and Al nanoparticle SPs, an 84-fold enhancement of the UV emission and an 8.3-fold enhancement of internal quantum efficiency (η_int) have been achieved under the optimized sputtering time and energy of SPs.

Peculiar near-band-edge emission of polarization-dependent XEOL from a non-polar a-plane ZnO wafer

Polarization-dependent hard X-ray excited optical luminescence (XEOL) was used to study not only the optical properties but also the crystallographic orientations of a non-polar a-plane ZnO wafer. In addition to a positive-edge jump and extra oscillations in the near-band-edge (NBE) XEOL yield, we observed a blue shift of the NBE emission peak that follows the polarization-dependent X-ray absorption near-edge structure (XANES) as the X-ray energy is tuned across the Zn K-edge. This NBE blue shift is caused by the larger X-ray absorption, generating higher free carriers to reduce the exciton-LO phonon coupling, which causes a decrease in the exciton activation energy. The extra oscillations in XANES and XEOL as the polarization is set parallel to the c-axis is attributed to simultaneous excitations of the Zn 4p - O 2pπ -bond along the c-axis and the bilayer σ-bond, whereas only the σ-bond is excited when the polarization is perpendicular to the c-axis. The polarization-dependent XEOL spectra can be used to determine the crystallographic orientations.

Great photoluminescence enhancement in Al-sputtered Zn0.78Mg0.22O films

Zn_0.78Mg_0.22O thin films were grown on a-plane sapphire substrates by plasma-assisted molecular beam epitaxy. Compared with ZnO, the crystal quality of Zn_0.78Mg_0.22O thin films degrades significantly, which results in low internal quantum efficiency (η_int). Besides improving the quality of Zn_0.78Mg_0.22O, an effective method has been used to enhance the internal quantum efficiency and the UV emission of Zn_0.78Mg_0.22O by sputtering Al nanoparticles. Taking advantage of the resonant coupling between UV emission of Zn_0.78Mg_0.22O film and Al nanoparticle surface plasmons (SPs), a 59-fold enhancement of the UV emission and a 3.5-fold enhancement of η_int has been achieved under the optimized sputtering time. Moreover, the enhancement ratio is stable after two months. It paves a facile way in fabricating high-efficiency UV optoelectronic devices.

Polarity control and enhanced luminescence characteristics of semi-polar ZnO nanostructures grown on non-polar MgO(100) substrates

Enhancing luminescence characteristics is one of the key challenges in ZnO nanostructures for highly efficient UV-blue LEDs and laser diodes. We report enhanced CL emission intensity by tailoring polar and non-polar ZnO nanostructures.