The origin of the red emission in n-ZnO nanotubes/p-GaN white light emitting diodes

Alvi, Naveed ul Hassan; Hasan, Kamran ul; Nur, Omer; Willander, Magnus

doi:10.1186/1556-276x-6-130

Cited by 263 publications

(118 citation statements)

References 33 publications

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“…or V Zn levels that are created in oxygen-rich conditions, 33,[41][42][43][44] as confirmed by DLTS. 36,37 In order to confirm the type of defects in these samples, PL measurements were carried out for the vacuum-annealed Sample D3 grown at 100 mTorr (Figure 4(c)).…”

Section: Resultsmentioning

confidence: 83%

Identifying the influence of the intrinsic defects in Gd-doped ZnO thin-films

Flemban

Sequeira

Zhang

et al. 2016

Journal of Applied Physics

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Gd-doped ZnO thin films were prepared using pulsed laser deposition at different oxygen pressures and varied Gd concentrations. The effects of oxygen deficiency-related defects on the Gd incorporation, optical and structural properties, were explored by studying the impact of oxygen pressure during deposition and post-growth thermal annealing in vacuum. Rutherford Backscattering Spectrometry revealed that the Gd concentration increases with increasing oxygen pressure for samples grown with the same Gd-doped ZnO target. Unexpectedly, the c-lattice parameter of the samples tends to decrease with increasing Gd concentration, suggesting that Gd-defect complexes play an important role in the structural properties. Using low-temperature photoluminescence (PL), Raman measurements and density functional theory calculations, we identified oxygen vacancies as the dominant intrinsic point defects. PL spectra show a defect band related to oxygen vacancies for samples grown at oxygen deficiency. V C 2016 AIP Publishing LLC.

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Section: Resultsmentioning

confidence: 83%

Identifying the influence of the intrinsic defects in Gd-doped ZnO thin-films

Flemban

Sequeira

Zhang

et al. 2016

Journal of Applied Physics

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“…In its most common form, the hexagonal wurtzite structure of ZnO has two different surfaces; one is the polar plane and includes respectively [61]. ZnO does not only emit in the UV region, it also emits covering the whole visible spectra which emits green, yellow and in the red region [62][63][64]. The UV spectrum is associated with near band-edge transition in ZnO, namely, the recombination of the free excitons.…”

Section: Zinc Oxide (Zno)mentioning

confidence: 99%

Synthesising Metal Oxide Materials and Their Composite Nanostructures for Sensing and Optoelectronic Device Applications

Khun¹

2015

Linköping Studies in Science and Technology. Dissertations

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Research on nanomaterials has been revolutionized in the last few years because of the attractive properties they have in comparison to the bulk phase of similar materials. These properties are physical, chemical, catalytic and optical. Among these nanomaterials, the metal oxide nanostructures have become of particular interest to scientists for the development of different optical, biochemical and biomedical nanodevices. In the present research work using the advantageous features of nanotechnology, high performance nanodevices for optoelectronics with a wide band gap compound nanostructure and highly sensitive sensor devices have been demonstrated. The nanotechnology is used to fabricate sensitive and precise nanodevices based on nanomaterials for the application of sensing.Among metal oxide nanostructures, ZnO, CuO and NiO are attractive materials because of their unique properties; their high surface area to volume ratio, their energy band gap of 3.37 eV, 1.2 eV and 3.7 eV, respectively, biocompatibility, high electron mobility, fast electron transfer rate and they are environmental-friendly in many applications. When used in sensor devices, nanomaterials have indicated high selectivity for possible use to detect the various analytes even in small volumes. Metal oxide nanostructures have shown to be good for optoelectronic nanodevices because of their electrical characteristics, high optical absorption and low-processing temperature.In this thesis, the synthesis of different morphologies of metal oxide semiconductor nanostructures and their composite using the hydrothermal method are demonstrated for various applications. This thesis is divided into three parts:In the first part of this research work, the fabrication of well-aligned ZnO nanorods using different concentrations of composite seed layer of inorganic and organic materials when using the hydrothermal growth method is presented. The effect of the composite seed layer on the i Abstract alignment, density and optical properties of the grown ZnO nanorods is investigated (paper I).Utilizing the advantage of ZnO nanostructure, a comparative study of ZnO nanorods and thin films for chemical and biosensing application was carried out. The ZnO nanorods and thin films were functionalized with strontium ionophore membrane, immobilized the galactose oxidase and lactate oxidase for determining the strontium ions, D-galactose and L-lactic acid, respectively (paper II).In the second part, the effects of different urea concentrations on the morphology of CuO nanostructures is studied as described in paper III. Moreover, CuO nanoflowers were functionalized with cadmium ion ionophore for the detection of Cd ions, while CuO nanosheets were grown by the low temperature growth method and were used for the development of a nonenzymatic glucose sensor, respectively (Paper IV).In the last part of this thesis, composite nanostructures of CuO/ZnO and NiO/ZnO were applied to develop dopamine sensor and fast sensitive UV photodetector, respectively. A nanohybrid of C...

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“…7,3 ZnO also possesses deep-level emission bands that emit all colors in the visible range with good color-rendering properties. 8 An understanding of the origins of emissions related to deep-level defects in ZnO for development of high efficiency optoelectronic devices is also required. There is a need to have control over the conductivity and defects in ZnO, i.e., by removing them if unwanted or introducing them when required.…”

Section: Introductionmentioning

confidence: 99%

Effects of high temperature annealing on single crystal ZnO and ZnO devices

Mtangi

Auret

Diale

et al. 2012

Journal of Applied Physics

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AlN thin film transducers for high temperature non-destructive testing applications J. Appl. Phys. 111, 074510 (2012) Fast programming metal-gate Si quantum dot nonvolatile memory using green nanosecond laser spike annealing Appl. Phys. Lett. 100, 143501 (2012) Al2O3/InAs metal-oxide-semiconductor capacitors on (100) and (111)B substrates Appl. Phys. Lett. 100, 132905 (2012) Sub-diffraction-limit semiconductor resonators operating on the fundamental magnetic resonance Appl. Phys. Lett. 100, 131113 (2012) Additional information on J. Appl. Phys. We have systematically investigated the effects of high-temperature annealing on ZnO and ZnO devices using current voltage, deep level transient spectroscopy (DLTS) and Laplace DLTS measurements. Current-voltage measurements reveal the decrease in the quality of devices fabricated on the annealed samples, with the high-temperature annealed samples yielding devices with low barrier heights and high reverse currents. DLTS results indicate the presence of three prominent defects in the as-received samples. Annealing the ZnO samples at 300 C, 500 C, and 600 C in Ar results in an increase in reverse leakage current of the Schottky contacts and an introduction of a new broad peak. After 700 C annealing, the broad peak is no longer present, but a new defect with an activation enthalpy of 0.18 eV is observed. Further annealing of the samples in oxygen after Ar annealing causes an increase in intensity of the broad peak. High-resolution Laplace DLTS has been successfully employed to resolve the closely spaced energy levels. V C 2012 American Institute of Physics. [http://dx

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The origin of the red emission in n-ZnO nanotubes/p-GaN white light emitting diodes

Cited by 263 publications

References 33 publications

Identifying the influence of the intrinsic defects in Gd-doped ZnO thin-films

Identifying the influence of the intrinsic defects in Gd-doped ZnO thin-films

Synthesising Metal Oxide Materials and Their Composite Nanostructures for Sensing and Optoelectronic Device Applications

Effects of high temperature annealing on single crystal ZnO and ZnO devices

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