Solution-based growth of ZnO nanorods for light-emitting devices: hydrothermal vs. electrodeposition

Ng, A. M. C.; Chen, Xin Yi; Fang, F.; Hsu, Yu‐Ling; Djurišić, Aleksandra B.; Ling, C. C.; Tam, Hoi Lam; Cheah, Kok Wai; Fong, W.K.; Lui, H. F.; Surya, C.; Chan, W. K.

doi:10.1007/s00340-010-4173-9

Cited by 36 publications

(34 citation statements)

References 42 publications

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“…2, are consistent with the presence of tunneling mechanisms and show a shape resembling the backward diode. 10,12,13,41 Similar I-V curve shapes can also be observed for QW1 and QW2 devices. 37 The contacts have been verified to be ohmic, 37 as illustrated in the inset of Fig.…”

Section: A I-v Curvessupporting

confidence: 64%

“…13 A platinum foil was used as the anode while the substrate was used as the cathode. The solution was heated up to 80 C. A fixed current of 10 mA was first applied for 1 min and then a fixed current of 1 mA was applied for another 29 min.…”

Section: Methodsmentioning

confidence: 99%

“…The tunneling is expected to occur due to the large energy band offset at p-GaN/n-ZnO interface. 4,8,10,12,13,28,[45][46][47] The yellow (or orange yellow) emission appears at relatively low bias voltages, so that it likely occurs due to tunneling. Tunneling phenomena in III-nitride heterojunctions have been previously observed for different material combinations.…”

Section: B Performance Under Reverse Biasmentioning

confidence: 99%

“…23 However, very different behavior has been reported for pGaN/n-ZnO devices even for similar device architectures, which makes it difficult to establish strategies for the improvement of device performance. For example, in addition to devices lighting up under forward bias, devices lighting up under reverse bias 4, [8][9][10]12,13,28 have been reported. Also, a variety of the emission peaks at different wavelengths have been observed, including UV, UV-violet, violet-blue, green, yellow, and orange-red, with multiple peaks frequently present 11,14,18,19,22 which in some cases results in white emission.…”

Section: Introductionmentioning

confidence: 99%

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ZnO nanorod/GaN light-emitting diodes: The origin of yellow and violet emission bands under reverse and forward bias

Chen

Fang

et al. 2011

Journal of Applied Physics

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Study of droop phenomena in InGaN-based blue and green light-emitting diodes by temperature-dependent electroluminescence Appl. Phys. Lett. 100, 153506 (2012) Silicon-nanocrystal resonant-cavity light emitting devices for color tailoring J. Appl. Phys. 111, 074512 (2012) Effects of energetic disorder on the low-frequency differential capacitance of organic light emitting diodes J. Appl. Phys. 111, 074506 (2012) Probing the electrode-polymer interface in conjugated polymer devices with surface-enhanced Raman scattering Appl. Phys. Lett. 100, 141907 (2012) Low-cost caesium phosphate as n-dopant for organic light-emitting diodes J. Appl. Phys. 111, 074502 (2012) Additional information on J. Appl. Phys. ZnO nanorods have been prepared by electrodeposition under identical conditions on various p-GaN-based thin film structures. The devices exhibited lighting up under both forward and reverse biases, but the turn-on voltage and the emission color were strongly dependent on the p-GaN-based structure used. The origin of different luminescence peaks under forward and reverse bias has been studied by comparing the devices with and without ZnO and by photoluminescence and cathodoluminescence spectroscopy. We found that both yellow-orange emission under reverse bias and violet emission under forward bias, which are commonly attributed to ZnO, actually originate from the p-GaN substrate and/or surface/interface defects. While the absolute brightness of devices without InGaN multiple quantum wells was low, high brightness with luminance exceeding 10 000 cd/m 2 and tunable emission (from orange at 2.1 V to blue at 2.7 V, with nearly white emission with Commission internationale de l'éclairage (CIE) coordinates (0.30, 0.31) achieved at 2.5 V) was obtained for different devices containing InGaN multiple quantum wells.

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Section: A I-v Curvessupporting

confidence: 64%

Section: Methodsmentioning

confidence: 99%

Section: B Performance Under Reverse Biasmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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ZnO nanorod/GaN light-emitting diodes: The origin of yellow and violet emission bands under reverse and forward bias

Chen

Fang

et al. 2011

Journal of Applied Physics

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“…[60][61][62][63][64][65] In general, the seed layer can be prepared in the form of thin film (TF) or nanoparticles (NPs) and then can be deposited on a certain substrate by several deposition techniques e.g., sputtering, spin coating and dip coating. [18,35,60] In particular, the NPs seed layer is often prepared by the dissolution of zinc acetate dihydrate (Zn(CH3COO)2.H2O) in organic solvents e.g., methanol, and the subsequent addition of a basic aqueous solution e.g., potassium hydroxide (KOH).…”

Section: Zno Seed Layer Preparationmentioning

confidence: 99%

Toward the Optimization of Low-temperature Solution-based Synthesis of ZnO Nanostructures for Device Applications

Alnoor¹

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One-dimensional (1D) nanostructures (NSs) of Zinc Oxide (ZnO) such as nanorods (NRs) have recently attracted considerable research attention due to their potential for the development of optoelectronic devices such as ultraviolet (UV) photodetectors and light-emitting diodes (LEDs). The potential of ZnO NRs in all these applications, however, would require synthesis of high crystal quality ZnO NRs with precise control over the optical and electronic properties. It is known that the optical and electronic properties of ZnO NRs are mostly influenced by the presence of native (intrinsic) and impurities (extrinsic) defects. Therefore, understanding the nature of these intrinsic and extrinsic defects and their spatial distribution is critical for optimizing the optical and electronic properties of ZnO NRs. However, identifying the origin of such defects is a complicated matter, especially for NSs, where the information on anisotropy is usually lost due to the lack of coherent orientation. Thus, the aim of this thesis is towards the optimization of the lowtemperature solution-based synthesis of ZnO NRs for device applications. In this connection, we first started with investigating the effect of the precursor solution stirring durations on the deep level defects concentration and their spatial distribution along the ZnO NRs. Then, by choosing the optimal stirring time, we studied the influence of ZnO seeding layer precursor’s types, and its molar ratios on the density of interface defects. The findings of these investigations were used to demonstrate ZnO NRs-based heterojunction LEDs. The ability to tune the point defects along the NRs enabled us further to incorporate cobalt (Co) ions into the ZnO NRs crystal lattice, where these ions could occupy the vacancies or interstitial defects through substitutional or interstitial doping. Following this, high crystal quality vertically welloriented ZnO NRs have been demonstrated by incorporating a small amount of Co into the ZnO crystal lattice. Finally, the influence of Co ions incorporation on the reduction of core-defects (CDs) in ZnO NRs was systematically examined using electron paramagnetic resonance (EPR)

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Controlled synthesis of ZnO nanoparticles from a Zn(II) coordination polymer: Structural characterization, optical properties and photocatalytic activity

Said

Aly

El‐Said

et al. 2020

Applied Organom Chemis

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A zinc coordination polymer derived from pyridine‐2,6‐dicarboxylate (PDC), {[Zn2(PDC)2]}n, was successfully prepared via conventional, sonication and microwave‐irradiation methods. The composition and characteristics of the obtained coordination polymers (CPs) were investigated by elemental analysis, TGA/DTA, X‐ray diffraction and spectroscopic techniques. The so obtained CPs were heat‐treated in the air at 600 °C for 2 h to produce ZnO of nanosized particles (NPs). It is of interest to note that the synthesis approach of the precursor greatly affects both the nanoparticle size and the structure of the resulting ZnO NPs. Moreover, the smallest particle size was associated with the sample derived from the ultrasonically prepared precursor. TEM analysis revealed that all samples have sphere‐like morphologies. Structural analysis of the prepared ZnO samples was conducted and compared using Rietveld analysis of their PXRD patterns. Optical band gap calculations based on analysis of the UV–vis spectra of ZnO samples using Tauc's power law were achieved. The highest band gap of 3.63 eV was observed for ZnO sample obtained from the ultrasonically prepared precursor. Furthermore, the photocatalytic activity of ZnO NPs for the removal of Eosin Y color was monitored. The highest removal efficiency was recorded for ZnO originated from the ultrasonically synthesized precursor. Enhancement of removal efficiency that reached 98% was attained in only a period of 8 min. Its recycling test showed that it can be reused without structural changes over four cycling experiments.

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Solution-based growth of ZnO nanorods for light-emitting devices: hydrothermal vs. electrodeposition

Cited by 36 publications

References 42 publications

ZnO nanorod/GaN light-emitting diodes: The origin of yellow and violet emission bands under reverse and forward bias

ZnO nanorod/GaN light-emitting diodes: The origin of yellow and violet emission bands under reverse and forward bias

Toward the Optimization of Low-temperature Solution-based Synthesis of ZnO Nanostructures for Device Applications

Controlled synthesis of ZnO nanoparticles from a Zn(II) coordination polymer: Structural characterization, optical properties and photocatalytic activity

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