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Alnoor, Hatim
Publications (8 of 8) Show all publications
David, D., Alnoor, H., Mancir da Silva Santana, V., Bargiela, P., Nur, O., Willander, M., . . . Ferreira da Silva, A. (2019). Optical properties from photoelectron energy-loss spectroscopy of low-temperature aqueous chemically synthesized ZnO nanorods grown on Si. Semiconductor Science and Technology, 34(4), Article ID 045019.
Open this publication in new window or tab >>Optical properties from photoelectron energy-loss spectroscopy of low-temperature aqueous chemically synthesized ZnO nanorods grown on Si
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2019 (English)In: Semiconductor Science and Technology, ISSN 0268-1242, E-ISSN 1361-6641, Vol. 34, no 4, article id 045019Article in journal (Refereed) Published
Abstract [en]

The optical properties of zinc oxide (ZnO) nanorods (NRs) synthesized by the low-temperature aqueous chemical method on top of silicon (Si) substrate have been investigated by means of photoelectron energy loss spectroscopy (PEELS). The ZnO NRs were obtained by the low temperature aqueous chemical synthesis on top of Si substrate. The measured valence band, the dynamical dielectric functions and optical absorption of the material show a reasonable agreement when the trending and shape of the theoretical calculations are considered. A first-principle calculation based on density functional theory (DFT) was performed using the partially self-consistent GW approximation (scGW0) and compared to the experimental results. The application of these two techniques brings a new analysis of the electronic properties of this material. The experimental results regarding the density of states (DOS) obtained for the valence band using x-ray photoelectron spectroscopy (XPS) was found to be consistent with the theoretical calculated value. Due to this consistency, the same wavefunctions was then employed to calculate the dielectric function of the ZnO NRs. The experimentally extracted dielectric function was also consistent with the calculated values.

Place, publisher, year, edition, pages
American Institute of Physics (AIP), 2019
Keywords
ZnO nanorods; optical properties; density of states; dielectric function; density functional theory
National Category
Physical Sciences
Identifiers
urn:nbn:se:liu:diva-155654 (URN)10.1088/1361-6641/ab0bc4 (DOI)000461940800007 ()
Note

Funding agencies: National Research Council of Scientific and Technological Development (CNP); Bahia Research Foundation (FAPESB)/PRONEX; CAPES Foundation within the Ministry of Education, Research Council of Norway [243642]

Available from: 2019-03-22 Created: 2019-03-22 Last updated: 2019-04-03Bibliographically approved
Alnoor, H. (2017). Toward the Optimization of Low-temperature Solution-based Synthesis of ZnO Nanostructures for Device Applications. (Doctoral dissertation). Linköping: Linköping University Electronic Press
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: 2019-10-11Bibliographically approved
Alnoor, H., Pozina, G., Khranovskyy, V., Liu, X., Iandolo, D., Willander, M. & Nur, O. (2016). Influence of ZnO seed layer precursor molar ratio on the density of interface defects in low temperature aqueous chemically synthesized ZnO nanorods/GaN light-emitting diodes. Journal of Applied Physics, 119(16), 165702
Open this publication in new window or tab >>Influence of ZnO seed layer precursor molar ratio on the density of interface defects in low temperature aqueous chemically synthesized ZnO nanorods/GaN light-emitting diodes
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2016 (English)In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 119, no 16, p. 165702-Article in journal (Refereed) Published
Abstract [en]

Low temperature aqueous chemical synthesis (LT-ACS) of zinc oxide (ZnO) nanorods (NRs) has been attracting considerable research interest due to its great potential in the development of light-emitting diodes (LEDs). The influence of the molar ratio of the zinc acetate (ZnAc): KOH as a ZnO seed layer precursor on the density of interface defects and hence the presence of non-radiative recombination centers in LT-ACS of ZnO NRs/GaN LEDs has been systematically investigated. The material quality of the as-prepared seed layer as quantitatively deduced by the X-ray photoelectron spectroscopy is found to be influenced by the molar ratio. It is revealed by spatially resolved cathodoluminescence that the seed layer molar ratio plays a significant role in the formation and the density of defects at the n-ZnO NRs/p-GaN heterostructure interface. Consequently, LED devices processed using ZnO NRs synthesized with molar ratio of 1:5M exhibit stronger yellow emission (similar to 575 nm) compared to those based on 1:1 and 1:3M ratios as measured by the electroluminescence. Furthermore, seed layer molar ratio shows a quantitative dependence of the non-radiative defect densities as deduced from light-output current characteristics analysis. These results have implications on the development of high-efficiency ZnO-based LEDs and may also be helpful in understanding the effects of the ZnO seed layer on defect-related non-radiative recombination. Published by AIP Publishing.

Place, publisher, year, edition, pages
AMER INST PHYSICS, 2016
National Category
Materials Chemistry
Identifiers
urn:nbn:se:liu:diva-129174 (URN)10.1063/1.4947593 (DOI)000375929900043 ()
Note

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

Available from: 2016-06-13 Created: 2016-06-13 Last updated: 2017-11-28
Alnoor, H., Chey, C. O., Pozina, G., Liu, X., Khranovskyy, V., Willander, M. & Nour, O. (2015). Effect of precursor solutions stirring on deep level defects concentration and spatial distribution in low temperature aqueous chemical synthesis of zinc oxide nanorods. AIP Advances, 5(8), Article ID 087180.
Open this publication in new window or tab >>Effect of precursor solutions stirring on deep level defects concentration and spatial distribution in low temperature aqueous chemical synthesis of zinc oxide nanorods
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2015 (English)In: AIP Advances, ISSN 2158-3226, E-ISSN 2158-3226, Vol. 5, no 8, article id 087180Article in journal (Refereed) Published
Abstract [en]

Hexagonal c-axis oriented zinc oxide (ZnO) nanorods (NRs) with 120-300 nm diameters are synthesized via the low temperature aqueous chemical route at 80 degrees C on silver-coated glass substrates. The influence of varying the precursor solutions stirring durations on the concentration and spatial distributions of deep level defects in ZnO NRs is investigated. Room temperature micro-photoluminesnce (mu-PL) spectra were collected for all samples. Cathodoluminescence (CL) spectra of the as-synthesized NRs reveal a significant change in the intensity ratio of the near band edge emission (NBE) to the deep-level emission (DLE) peaks with increasing stirring durations. This is attributed to the variation in the concentration of the oxygen-deficiency with increasing stirring durations as suggested from the X-ray photoelectron spectroscopy analysis. Spatially resolved CL spectra taken along individual NRs revealed that stirring the precursor solutions for relatively short duration (1-3 h), which likely induced high super saturation under thermodynamic equilibrium during the synthesis process, is observed to favor the formation of point defects moving towards the tip of the NRs. In contrary, stirring for longer duration (5-15 h) will induce low super saturation favoring the formation of point defects located at the bottom of the NRs. These findings demonstrate that it is possible to control the concentration and spatial distribution of deep level defects in ZnO NRs by varying the stirring durations of the precursor solutions.

Place, publisher, year, edition, pages
AMER INST PHYSICS, 2015
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:liu:diva-122070 (URN)10.1063/1.4929981 (DOI)000360655900089 ()
Note

Funding Agencies|Avdanced Functional Materials (AFM) SFO project at Linkoping Univeristy, Sweden

Available from: 2015-12-18 Created: 2015-10-19 Last updated: 2017-12-01
Hatamie, A., Khan, A., Golabi, M., Turner, A., Beni, V., Mak, W. C., . . . Willander, M. (2015). Zinc Oxide Nanostructure-Modified Textile and Its Application to Biosensing, Photocatalysis, and as Antibacterial Material. Langmuir, 31(39), 10913-10921
Open this publication in new window or tab >>Zinc Oxide Nanostructure-Modified Textile and Its Application to Biosensing, Photocatalysis, and as Antibacterial Material
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2015 (English)In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 31, no 39, p. 10913-10921Article in journal (Refereed) Published
Abstract [en]

Recently, one-dimensional nanostructures with different morphologies (such as nanowires, nanorods (NRs), and nanotubes) have become the focus of intensive research, because of their unique properties with potential applications. Among them, zinc oxide (ZnO) nanomaterials has been found to be highly attractive, because of the remarkable potential for applications in many different areas such as solar cells, sensors, piezoelectric devices, photodiode devices, sun screens, antireflection coatings, and photocatalysis. Here, we present an innovative approach to create a new modified textile by direct in situ growth of vertically aligned one-dimensional (1D) ZnO NRs onto textile surfaces, which can serve with potential for biosensing, photocatalysis, and antibacterial applications. ZnO NRs were grown by using a simple aqueous chemical growth method. Results from analyses such as X-ray diffraction (XRD) and scanning electron microscopy (SEM) revealed that the ZnO NRs were dispersed over the entire surface of the textile. We have demonstrated the following applications of these multifunctional textiles: (1) as a flexible working electrode for the detection of aldicarb (ALD) pesticide, (2) as a photo catalyst for the degradation of organic molecules (i.e., Methylene Blue and Congo Red), and (3) as antibacterial agents against Escherichia coli. The ZnO-based textile exhibited excellent photocatalytic and antibacterial activities, and it showed a promising sensing response. The combination of sensing, photo catalysis, and antibacterial properties provided by the ZnO NRs brings us closer to the concept of smart textiles for wearable sensing without a deodorant and antibacterial control. Perhaps the best known of the products that is available in markets for such purposes are textiles with silver nanoparticles. Our modified textile is thus providing acceptable antibacterial properties, compared to available commercial modified textiles.

Place, publisher, year, edition, pages
AMER CHEMICAL SOC, 2015
National Category
Other Chemistry Topics Materials Chemistry
Identifiers
urn:nbn:se:liu:diva-122428 (URN)10.1021/acs.langmuir.5b02341 (DOI)000362629000033 ()26372851 (PubMedID)
Note

Funding Agencies|Shahid Chamran University; AFM/SFO project at Linkoping University

Available from: 2015-11-03 Created: 2015-11-02 Last updated: 2017-12-01
Chey, C. O., Liu, X., Alnoor, H., Nur, O. & Willander, M. (2014). Fast piezoresistive sensor and UV photodetector based on Mn-doped ZnO nanorods. Physica Status Solidi. Rapid Research Letters, 9(1), 87-91
Open this publication in new window or tab >>Fast piezoresistive sensor and UV photodetector based on Mn-doped ZnO nanorods
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2014 (English)In: Physica Status Solidi. Rapid Research Letters, ISSN 1862-6254, E-ISSN 1862-6270, Vol. 9, no 1, p. 87-91Article in journal (Refereed) Published
Abstract [en]

A low cost hydrothermal synthesis method to synthesize Mn-doped ZnO nanorods (NRs) with controllable morphology and structure has been developed. Ammonia is used to tailor the ammonium hydroxide concentration, which provides a source of OH– for hydrolysis and precipitation during the growth instead of HMT. The morphological, chemical composition, structural, and electronic structure studies of the Mn-doped ZnO NRs show that the Mn-doped ZnO NRs have a hexagonal wurtzite ZnO structure along the c-axis and the Mn ions replace the Zn sites in the ZnO NRs matrix without any secondary phase of metallic manganese element and manganese oxides observed. The fabricated PEDOT:PSS/Zn0.85Mn0.15O Schottky diode based piezoresistive sensor and UV photodetector shows that the piezoresistive sensor has pressure sensitivity of 0.00617 kPa–1 for the pressure range from 1 kPa to 20 kP and 0.000180 kPa–1for the pressure range from 20 kPa to 320 kPa with relatively fast response time of 0.03 s and the UV photodetector has both relatively high responsivity and fast response time of 0.065 A/W and 2.75 s, respectively. The fabricated Schottky diode can be utilized as a very useful human-friendly interactive electronic device for mass/force sensor or UV photodetector in everyday living life. This developed device is very promising for small-size, low-cost and easy-to-customize application-specific requirements. (© 2014 WILEY-VCH Verlag GmbH &Co. KGaA, Weinheim)

Place, publisher, year, edition, pages
John Wiley & Sons, 2014
Keywords
ZnO nanorods, Mn doping, hydrothermal method, piezoresistive sensors, ultraviolet photodetectors, optical properties
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:liu:diva-112912 (URN)10.1002/pssr.201409453 (DOI)000348763500015 ()
Available from: 2014-12-19 Created: 2014-12-19 Last updated: 2017-12-05Bibliographically approved
Chey, C. O., Alnoor, H., Abbasi, M. A., Nur, O. & Willander, M. (2014). Fast synthesis, morphology transformation, structural and optical properties of ZnO nanorods grown by seed-free hydrothermal method. Physica Status Solidi (a) applications and materials science, 211(11), 2611-2615
Open this publication in new window or tab >>Fast synthesis, morphology transformation, structural and optical properties of ZnO nanorods grown by seed-free hydrothermal method
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2014 (English)In: Physica Status Solidi (a) applications and materials science, ISSN 1862-6300, E-ISSN 1862-6319, Vol. 211, no 11, p. 2611-2615Article in journal (Refereed) Published
Abstract [en]

A fast and low cost seed-free hydrothermal synthesis method to synthesize zinc oxide (ZnO) nanorods with controllable morphology, size and structure has been developed. Ammonia is used to react with water to tailor the ammonium hydroxide concentration, which provides a continuous source of OH− for hydrolysis and precipitation of the final products. Hence, allowing ZnO nanorods to growth on large areas of metal (Au and Ag coated glass), p-type Si and organic flexible (PEDOT: PSS) substrates. Increasing the growth time, the morphology transforms from pencil-like to hexagonal shape rod-like morphology. Within one hour the length of the ZnO nanorods has reached almost 1 µm. The optical characteristics has shown that the grown ZnO nanorods are dominated by two emission peaks, one is in the UV range centered at 381 nm and other one with relatively high intensity appears in the visible range and centered at 630 nm. While the growth duration was increased from 2 h to 6 h, the optical band gap was observed to increase from 2.8 eV to 3.24 eV, respectively. This fast and low cost method is suitable for LEDs, UV-photodetector, sensing, photocatalytic, multifunctional devices and other optoelectronic devices, which can be fabricated on any substrates, including flexible and foldable substrates.

Keywords
hydrothermal method, low temperature growth, seed-free growth ZnO, ZnO nanorods
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:liu:diva-112903 (URN)10.1002/pssa.201431311 (DOI)000344461800029 ()
Available from: 2014-12-19 Created: 2014-12-19 Last updated: 2017-12-05Bibliographically approved
Chey, C. O., Alnoor, H., Liu, X., Abbasi, M. A., Nur, O. & Willander, M.ZnO nanorods based piezoresistive sensor synthesized by rapid mixing hydrothermal method.
Open this publication in new window or tab >>ZnO nanorods based piezoresistive sensor synthesized by rapid mixing hydrothermal method
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(English)Manuscript (preprint) (Other academic)
Abstract [en]

We have successfully synthesized well-aligned, shape controlled and uniform size distribution of ZnO nanorods by using a rapid mixing hydrothermal method. The scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) characterizations showed that the ZnO nanorods grow along the c-axis with hexagonal wurtzite ZnO structure. The room temperature cathodoluminescence (CL) investigation revealed that the ZnO nanorods have optical emissions in both the UV and visible ranges and the crystal quality of the ZnO nanorods can be improved by increasing the growth duration. The well-aligned and uniform ZnO nanorods were used to fabricate efficient piezoresistive sensor. The piezoresistive sensor has demonstrated a pressure sensitivity of 0.033 KPa-1 with a fast response and recovery times within 0.088 and 0.29 s, respectively. The piezoresistive sensor has potential applications in industrial, civil and transportation fields. Furthermore, the fabricated sensor can be utilized as a very useful human-friendly interactive electronic device for load sensing.

Keywords
Growth ZnO nanorods, rapid mixing hydrothermal method, piezoresistive sensor
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:liu:diva-112905 (URN)
Available from: 2014-12-19 Created: 2014-12-19 Last updated: 2015-01-13
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