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ZnO nanostructures for optoelectronics: Material properties and device applications

A common misconception is that the irradiation of solids with energetic electrons and ions has exclusively detrimental effects on the properties of target materials. In addition to the well-known cases of doping of bulk semiconductors and ion beam nitriding of steels, recent experiments show that irradiation can also have beneficial effects on nanostructured systems. Electron or ion beams may serve as tools to synthesize nanoclusters and nanowires, change their morphology in a controllable manner, and tailor their mechanical, electronic, and even magnetic properties. Harnessing irradiation as a tool for modifying material properties at the nanoscale requires having the full microscopic picture of defect production and annealing in nanotargets. In this article, we review recent progress in the understanding of effects of irradiation on various zero-dimensional and one-dimensional nanoscale systems, such as semiconductor and metal nanoclusters and nanowires, nanotubes, and fullerenes. We also consider the t...

Ion and electron irradiation-induced effects in nanostructured materials

1D metal-oxide nanostructures have attracted much attention because metal oxides are the most fascinating functional materials. The 1D morphologies can easily enhance the unique properties of the metal-oxide nanostructures, which make them suitable for a wide variety of applications, including gas sensors, electrochromic devices, light-emitting diodes, field emitters, supercapacitors, nanoelectronics, and nanogenerators. Therefore, much effort has been made to synthesize and characterize 1D metal-oxide nanostructures in the forms of nanorods, nanowires, nanotubes, nanobelts, etc. Various physical and chemical deposition techniques and growth mechanisms are exploited and developed to control the morphology, identical shape, uniform size, perfect crystalline structure, defects, and homogenous stoichiometry of the 1D metal-oxide nanostructures. Here a comprehensive review of recent developments in novel synthesis, exceptional characteristics, and prominent applications of one-dimensional nanostructures of tungsten oxides, molybdenum oxides, tantalum oxides, vanadium oxides, niobium oxides, titanium oxides, nickel oxides, zinc oxides, bismuth oxides, and tin oxides is provided.

One-Dimensional Metal-Oxide Nanostructures: Recent Developments in Synthesis, Characterization, and Applications

Semiconductor micro/nano-cavities with high quality factor (Q) and small modal volume provide critical platforms for exploring strong light-matter interactions and quantum optics, enabling further development of coherent and quantum photonic devices. Constrained by exciton binding energy and thermal fluctuation, only a handful of wide-band semiconductors such as ZnO and GaN have stable excitons at room temperature. Metal halide perovskite with cubic lattice and well-controlled exciton may provide solutions. In this work, high-quality single-crystalline cesium lead halide CsPbX3 (X = Cl, Br, I) whispering-gallery-mode (WGM) microcavities are synthesized by vapor-phase van der Waals epitaxy method. The as-grown perovskites show strong emission and stable exciton at room temperature over the whole visible spectra range. By varying the halide composition, multi-color (400–700 nm).WGM excitonic lasing is achieved at room temperature with low threshold (~ 2.0 μJ cm−2) and high spectra coherence (~0.14–0.15 nm). The results advocate the promise of inorganic perovskites towards development of optoelectronic devices and strong light-matter coupling in quantum optics.

/pdf/high-quality-whispering-gallery-mode-lasing-from-cesium-lead-5aoufrknta.pdf

High-Quality Whispering-Gallery-Mode Lasing from Cesium Lead Halide Perovskite Nanoplatelets

O N In recent years, low-dimensional semiconductor structures have attracted extensive research interest because of their fundamental importance and wide range of potential applications in nanotechnology. Notable achievements have been witnessed by light-emitting devices, lasers, and solar cells based on group IV elements (Si and Ge), [ 1 ] and group III–V (GaN and GaAs), [ 2 ] and II–VI compound semiconductors (ZnO, ZnS, and CdSe). [ 3–6 ]

/pdf/room-temperature-excitonic-whispering-gallery-mode-lasing-5bfklbed1q.pdf

Room Temperature Excitonic Whispering Gallery Mode Lasing from High‐Quality Hexagonal ZnO Microdisks

Ultraviolet electroluminescence was demonstrated at room temperature from a ZnO rod homojunction light-emitting diode array The p-type doping was realized by phosphorous (P) ion implantation into defect-free ZnO rods followed by annealing High resolution transmission electron microscopy shows the lattice compression of annealed single crystalline P-doped ZnO rod compared to the as-grown ZnO rod, suggesting atomically incorporation of P into the ZnO wurtzite structure p-type doping was confirmed by low temperature photoluminescence spectra and single rod current-voltage characterization

https://dr.ntu.edu.sg/bitstream/10220/6882/1/27. ultraviolet emission from a zno rod homojunction light-emitting diode.pdf

Ultraviolet emission from a ZnO rod homojunction light-emitting diode

n-ZnO nanorod/p-CuAlO 2 heterojunction light-emitting diodes have been fabricated on p + -Si substrates. The CuAlO 2 thin film was deposited by dc-magnetron sputtering while the ZnO nanorods (NRs) were fabricated using the vapor-phase transport method. The current–voltage characteristics of the devices showed good rectifying behavior with a high forward-to-reverse current ratio of around 120 at ±7 V. Strong ultraviolet electro-luminescence centered at ∼390 nm and a broad green-band emission were observed from the diode at room-temperature. The p-CuAlO 2 layer was found to facilitate hole injection from p + -Si into n-ZnO while confining the electrons at ZnO/CuAlO 2 interface, thus effectively enhancing the recombination emission efficiency in ZnO NRs.

/pdf/electroluminescence-from-a-n-zno-nanorod-p-cualo2-iit8hvy1qs.pdf

Electroluminescence from a n-ZnO nanorod/p-CuAlO2 heterojunction light-emitting diode

Single-crystalline zero-dimensional tin dioxide (SnO2) nanoparticles and one-dimensional SnO2 nanobelts were synthesized on silicon (Si) substrates with different seed layer coatings by simple vapo...

A SnO2 Nanoparticle/Nanobelt and Si Heterojunction Light-Emitting Diode

Wide-range color tuning from red to blue was achieved in phosphor-free p+-Si/p-CuAlO2/n-ZnO nanorod light-emitting diodes at room temperature. CuAlO2 films were deposited on p+-Si substrates by sputtering followed by annealing. ZnO nanorods were further grown on the annealed p+-Si/p-CuAlO2 substrates by vapor phase transport. The color of the p-CuAlO2/n-ZnO nanorod array heterojunction electroluminescence depended on the annealing temperature of the CuAlO2 film. With the increase of the annealing temperature from 900 to 1050 °C, the emission showed a blueshift under the same forward bias. The origin of the blueshift is related to the amount of Cu concentration diffused into ZnO.

/pdf/color-tunable-light-emitting-diodes-based-on-p-si-p-cualo2-n-3919dicw35.pdf

Bo Ling

Papers

Room Temperature Excitonic Whispering Gallery Mode Lasing from High‐Quality Hexagonal ZnO Microdisks

Ultraviolet emission from a ZnO rod homojunction light-emitting diode

Electroluminescence from a n-ZnO nanorod/p-CuAlO2 heterojunction light-emitting diode

A SnO2 Nanoparticle/Nanobelt and Si Heterojunction Light-Emitting Diode

Color tunable light-emitting diodes based on p+-Si/p-CuAlO2/n-ZnO nanorod array heterojunctions