Epitaxial growth of vertically aligned ZnO nanowires for bidirectional direct-current driven light-emitting diodes applications

Abstract

We presented a comparative investigation on the morphological and structural properties of the produced ZnO nanowires (NWs) on c-Al 2 O 3 substrates under different preparation conditions. The effects of a lowtemperature nucleation layer, reaction pressure and light irradiation on the alignment, diameter and growth rate of ZnO NWs were evaluated in detail. It was found that the low-temperature nucleation layer acting as a supporting layer favored the formation of a transition layer featuring initially a rough surface and a high density of grain boundaries, guiding and facilitating the subsequent homoepitaxy of ZnO NWs grown on the top of developed (0001) facets of the new activation sites. The crystallinity and vertical alignment of epitaxial ZnO NWs were further optimized to achieve the best value, as the second growth stage was conducted with a higher reaction pressure and light irradiation, such that a relatively low full width at halfmaximum (701 arcsec) of the rocking curve could be obtained. The thermodynamical growth kinetics of the produced ZnO NWs via the two-step growth process was also investigated by monitoring the morphology evolution at different growth stages. Coaxial n-ZnO/MgO/p-NiO-core/shell NWs heterostructured light-emitting diodes (LEDs) were then fabricated and characterized, and a unique tunability of the electroluminescence (EL) spectra depending on the bias polarities was observed. We studied in detail the bicolor EL characteristic of the bidirectional direct-current driven LEDs and tentatively proposed carrier tunneling and hole generation models to explain such interesting features. 40 | CrystEngComm, 2015, 17, 40-49 This journal is

All Transparent Metal Oxide Ultraviolet Photodetector

“…Due to its versatile material properties, NiO material has been used in a variety of applications, such as energy conversion (anode buffer layer in organic solar cells, transparent solar cells, piezoelectric nanogenerator, and photoelectrochemical cells), energy storage (Li‐ion batteries, rechargeable batteries, and supercapacitors), light generation (Light‐emitting devices and double‐side electroluminescence, electronic circuits (transparent conducting layers, transparent diodes, switching, memory,) and logic circuits, and energy sensing (gas sensors, multispectral photodetectors, and UV photodetectors (please refer Table 1 )).…”

Review—Growth of Al-, Ga-, and In-Doped ZnO Nanostructures via a Low-Temperature Process and Their Application to Field Emission Devices and Ultraviolet Photosensors

“…Moreover, their application in devices, such as field-effect transistors, 19,20 ultraviolet (UV) photosensors, 21,22 UV light-emitting diodes, 23 glucose sensors, 24,25 varistors, 26 gas sensors, 27 laser diodes, 28 surface acoustic wave (SAW) devices, 29 solar cells, 30,31 memory devices, 32,33 and field emission (FE) devices, 34 is promising. In recent years, FE devices have gained widespread attention for their application in flat-panel displays and other electronic devices, such as microwave amplifiers, high-brightness electron-source X-ray tubes, cathode-ray tube monitors, and electron microscopes.…”

High selectivity to ethanol gas sensor based on ZnO nanosheets decorated with Ag nanoparticles by aqueous solution and photochemical deposition

“…ZnO nanostructure have many synthetic methods, such as hydrothermal method (HTM), chemical vapor deposition (CVD), aqueous solution methods (ASM), pulsed laser deposition (PLD), electrochemical deposition (ECD), and electron-beam lithography (EBL) 8,[12][13][14][15][16][17][18][19] . Currently, ZnO nanostructures have been applied to optical and electronic devices, such as field-effect transistors (FETs), UV photodetectors (UV PD), light emitting diodes (LEDs), glucose sensors, varistors devices, gas sensors [20][21][22][23][24][25][26][27][28] .…”