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Seed layer synthesis effect on the concentration of interface defects and emission spectra of ZnO nanorods/p-GaN light-emitting diode
Linköping University, Department of Science and Technology. Linköping University, Faculty of Science & Engineering.
Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.ORCID iD: 0000-0002-9840-7364
Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.ORCID iD: 0000-0001-6235-7038
Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
2017 (English)In: Physica Status Solidi (a) applications and materials science, ISSN 1862-6300, E-ISSN 1862-6319, Vol. 214, no 1, article id 1600333Article in journal (Refereed) Published
Abstract [en]

As the low-temperature aqueous chemical synthesis (LT-ACS), holds great promises for the synthesis of one-dimensional (1D) ZnO nanostructure-based light-emitting diodes (LEDs) and hence require parameter tuning for optimal performance. N-ZnO nanorods (NRs)/p-GaN heterojunction LEDs have been synthesized by the LT-ACS using ZnO nanoparticle (NPs) seed layers prepared with different precursor solutions. The effect of these seed layers on the interface defect properties and emission intensity of the as-synthesized n-Zn/p-GaN heterojunction LEDs has been demonstrated by spatially resolved cathodoluminescence (CL) and electroluminescence (EL) measurements, respectively. A significant reduction of the interface defects in the n-ZnO NRs/p-GaN heterostructure synthesized from a seed layer prepared from zinc acetate (ZnAc) with a mixture of potassium hydroxide (KOH) and hexamethylenetetramine (HMTA) (donated as ZKH seed) compared with those prepared from ZnAc and KOH (donated as ZK seed) is observed as revealed by spatially resolved CL. Consequently, the LEDs based on n-ZnO NRs/p-GaN prepared from ZKH seed show an improvement in the yellow emission (approximate to 578nm) compared to that based on the ZK seed as deduced from the electroluminescence measurements. The improvement in the yellow EL emission on the ZKH LED probably attributed to the low presence of the non-radiative defect as deduced by light-output current (L-I) characteristics analysis.

Place, publisher, year, edition, pages
WILEY-V C H VERLAG GMBH , 2017. Vol. 214, no 1, article id 1600333
Keyword [en]
GaN; interface defects; light-emitting diodes; low-temperature aqueous chemical synthesis; seed layers; ZnO
National Category
Condensed Matter Physics
Identifiers
URN: urn:nbn:se:liu:diva-136230DOI: 10.1002/pssa.201600333ISI: 000394423400006OAI: oai:DiVA.org:liu-136230DiVA: diva2:1086222
Note

Funding Agencies|Swedish Government Strategic Research Area in Materials Science on Functional Materials (Faculty Grant SFO-Mat-LiU) at Linkoping University [2009-00971]

Available from: 2017-03-31 Created: 2017-03-31 Last updated: 2017-11-29
In thesis
1. Toward the Optimization of Low-temperature Solution-based Synthesis of ZnO Nanostructures for Device Applications
Open this publication in new window or tab >>Toward the Optimization of Low-temperature Solution-based Synthesis of ZnO Nanostructures for Device Applications
2017 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

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).

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2017. p. 67
Series
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 1871
National Category
Condensed Matter Physics Materials Chemistry
Identifiers
urn:nbn:se:liu:diva-141753 (URN)10.3384/diss.diva-141753 (DOI)9789176854815 (ISBN)
Public defence
2017-10-27, K3, Kåkenhus, Campus Norrköping, Norrköping, 10:15 (English)
Opponent
Supervisors
Available from: 2017-10-06 Created: 2017-10-06 Last updated: 2017-10-06Bibliographically approved

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