ZnO p-n junction light-emitting diodes fabricated on sapphire substrates

Jiao, Shujie; Zhang, Z. Z.; Lu, Youming; Shen, Dezhen; Ye, Bin; Zhang, J. Y.; Li, B. H.; Zhao, Dongxu; Fan, X.W.; Tang, Zikang

doi:10.1063/1.2166686

Cited by 275 publications

(112 citation statements)

References 16 publications

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“…The ZnO nanoparticles are of great interest for researchers due to their potential applications in ultraviolet (UV) to blue-violet light-emitting devices [1][2][3], photocatalysis [4,5], dye-sensitized solar cell [6], diluted magnetic semiconductors [7,8], etc. It is already well known that the optical properties of ZnO nanoparticles can be modulated by doping the ZnO matrix with different metal ions, i.e., classical 3d transition metals or rare earth metals, and/or by modifying the morphological characteristics [9,10].…”

Section: Introductionmentioning

confidence: 99%

A valence states approach for luminescence enhancement by low dopant concentration in Eu-doped ZnO nanoparticles

et al. 2015

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The paper presents a simple, reproducible, controllable, and direct wet chemical synthesis method for Zn 1-x Eu x O nanoparticles. The full understanding of decomposition mechanism of the as-obtained oxalate precipitate was achieved based on the thermal analysis correlated with the evolved gas analysis and FTIR spectroscopy. The structure, morphology, and optical luminescent properties of the Zn 1-x Eu x O nanoparticles have been investigated by X-ray diffraction, Raman spectroscopy, HRTEM, SAED, XPS, and PL. The XRD studies reveal the formation of a hexagonal wurtzite-type structure. The presence of Eu 2 O 3 cubic structure can be observed up to 0.5 mol% Eu, suggesting that the solubility of the divalent or trivalent Eu into the ZnO lattice is limited. The formation of Eu 2 O 3 secondary phase at higher Eu concentration is sustained by Raman spectroscopy and XPS, as well. The TEM investigations of the Eu-doped ZnO samples illustrate the presence of aggregates with different shapes and dimensions formed by agglomerated spherical and polyhedral nanoparticles with sizes ranging from 20 to 120 nm. The effect of europium concentration on the structural and morphological characteristics, as well as on the luminescent properties was studied with special emphasis on the europium chemical states-Eu 2? and Eu 3? . The PL measurements sustain the presence of both divalent and trivalent europium ions into the ZnO host lattice and, at the same time, an increase of its defects density induced by the dopant presence.

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Section: Introductionmentioning

confidence: 99%

A valence states approach for luminescence enhancement by low dopant concentration in Eu-doped ZnO nanoparticles

et al. 2015

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“…Several hybrid LEDs have been proposed, with either n-type ZnO 7-10 or n-type MgZnO layers, [11][12][13] using III-V nitrides for the p-layers. Fully ZnO-based LEDs presented in the recent literature include, e.g., bulk p-i-n ZnO structures, 14 bulk p-n ZnO structures, [15][16][17][18][19][20][21][22][23][24][25][26][27] MgZnO/CdZnO double heterostructures, 8 p-n MgZnO structures, 28 ZnO/MgZnO single quantum wells (SQWs), [29][30][31] and ZnO/MgZnO multiple quantum wells (MQWs). 32 The demonstration of the first BeZnO/ZnO MQW LEDs 33 and lasers 34 has stimulated significant experimental and theoretical work also on BeZnO, [35][36][37][38] an interesting alternative to MgZnO because it crystallizes in the wurtzite phase over its entire composition range.…”

Section: Introductionmentioning

confidence: 99%

Electronic and Optical Properties of Mg x Zn1−x O and Be x Zn1−x O Quantum Wells

Furno

Chiaria

Penna

et al. 2010

Journal of Elec Materi

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As a preparatory step toward establishing reliable numerical design tools for ZnO-based optoelectronic devices, we have reassessed the available information on material parameters relevant for the simulation of light-emitting diodes (LEDs) with active regions including ZnO, MgZnO, and BeZnO layers. The impact of different approximations for the electronic structure and the interface polarization charge on the optical properties of bulk ZnO and ZnO/MgZnO quantum wells has been evaluated, and a consistent set of parameters has been used not only for systematic comparison of ZnO/MgZnO and ZnO/BeZnO single quantum well structures but also for the first simulation of a realistic ZnO/BeZnO multiple quantum well LED.

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“…p-type ZnO is achievable but difficult to control and stabilize over time. Examples include p-i-n homojunctions, 50 p-n homojunction light emitting diodes, 51 and p-Cu:ZnO/n-6 H:SiC p-n heterojunctions, 52 each of which emit light with electric current. Very recently, Liu et al have demonstrated lasing within ZnO nanorods.…”

Section: Defect Roles In Achieving Controlled Dopingmentioning

confidence: 99%

Interplay of native point defects with ZnO Schottky barriers and doping

Brillson¹,

Dong²,

Tuomisto³

et al. 2012

Journal of Vacuum Science &Amp; Technology B, Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phen

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A combination of depth-resolved electronic and structural techniques reveals that native point defects can play a major role in ZnO Schottky barrier formation and charged carrier doping. Previous work ignored these lattice defects at metal-ZnO interfaces due to relatively low point defect densities in the bulk. At higher densities, however, they may account for the wide range of Schottky barrier results in the literature. Similarly, efforts to control doping type and density usually treat native defects as passive, compensating donors or acceptors. Recent advances provide a deeper understanding of the interplay between native point defects and electronic properties at ZnO surfaces, interfaces, and epitaxial films. Key to ZnO Schottky barrier formation is a massive redistribution of native point defects near its surfaces and interfaces. It is now possible to measure the energies, densities, and in many cases the type of point defects below the semiconductor-free surface and its metal interface with nanoscale precision. Depth-resolved cathodoluminescence spectroscopy of deep level emissions calibrated with electrical techniques show that native point defects can (1) increase by orders of magnitude in densities within tens of nanometers of the semiconductor surface, (2) alter free carrier concentrations and band profiles within the surface space charge region, (3) dominate Schottky barrier formation for metal contacts to ZnO, and (4) play an active role in semiconductor doping. The authors address these issues by clearly identifying transition energies of leading native point defects and defect complexes in ZnO and the effects of different annealing methods on their spatial distributions on a nanoscale. These results reveal the interplay between ZnO electronic defects, dopants, polarity, and surface nanostructure, highlighting new ways to control ZnO Schottky barriers and doping.

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ZnO p-n junction light-emitting diodes fabricated on sapphire substrates

Cited by 275 publications

References 16 publications

A valence states approach for luminescence enhancement by low dopant concentration in Eu-doped ZnO nanoparticles

A valence states approach for luminescence enhancement by low dopant concentration in Eu-doped ZnO nanoparticles

Electronic and Optical Properties of Mg x Zn1−x O and Be x Zn1−x O Quantum Wells

Interplay of native point defects with ZnO Schottky barriers and doping

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