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Bano, Nargis
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Publications (10 of 21) Show all publications
Yousuf Soomro, M., Hussain, I., Bano, N., Nur, O. & Willander, M. (2013). Annealing effect on the electrical and optical properties of Au/n-ZnO NWs Schottky diodes white LEDs. Superlattices and Microstructures, 62, 200-206
Open this publication in new window or tab >>Annealing effect on the electrical and optical properties of Au/n-ZnO NWs Schottky diodes white LEDs
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2013 (English)In: Superlattices and Microstructures, ISSN 0749-6036, E-ISSN 1096-3677, Vol. 62, p. 200-206Article in journal (Refereed) Published
Abstract [en]

We report the post-growth heat treatment effect on the electrical and the optical properties of hydrothermally grown zinc oxide (ZnO) nanowires (NWs) Schottky white light emitting diodes (LEDs). It was found that there is a changed in the electroluminescence (EL) spectrum when post growth annealing process was performed at 600 degrees C under nitrogen, oxygen and argon ambients. The EL spectrum for LEDs based on the as grown NWs show three bands red, green and blue centered at 724, 518 and 450 nm respectively. All devices based on ZnO NWs annealed in oxygen (O-2), nitrogen (N-2) and argon (Ar) ambient show blue shift in the violet and the red emissions whereas a red shift is observed in the green emission compared to the as grown NWs based device. The color rendering index (CRI) and the correlated color temperature (CCT) of all LEDs were calculated to be in the range 78-91 and 2753-5122 K, respectively. These results indicate that light from the LEDs can be tuned from cold white light to warm white light by post growth annealing.

Place, publisher, year, edition, pages
Elsevier, 2013
Keywords
ZnO nanowires, Schottky diodes, Post growth annealing, Electroluminescence
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-100481 (URN)10.1016/j.spmi.2013.07.014 (DOI)000325588700022 ()
Available from: 2013-11-08 Created: 2013-11-08 Last updated: 2018-02-20
Yousuf Soomro, M., Hussain, S., Bano, N., Hussain, I., Nur, O. & Willander, M. (2013). Hybrid organic zinc oxide white-light-emitting diodes on disposable paper substrate. Physica Status Solidi (a) applications and materials science, 210(8), 1600-1605
Open this publication in new window or tab >>Hybrid organic zinc oxide white-light-emitting diodes on disposable paper substrate
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2013 (English)In: Physica Status Solidi (a) applications and materials science, ISSN 1862-6300, E-ISSN 1862-6319, Vol. 210, no 8, p. 1600-1605Article in journal (Refereed) Published
Abstract [en]

ZnO-organic hybrid white-light-emitting diodes (WLEDs) were demonstrated on a paper substrate. The configuration used for ZnO-organic hybrid WLEDs consists a layer of poly (9,9)-(dioctylfluorene) (PFO) on poly (3,4-ethylenedioxythiophene) poly (styrenesulfonate) (PEDOT: PSS) on n-type ZnO nanorods grown by a low-temperature chemical aqueous method on paper substrate. Room temperature photoluminescence, electroluminescence, and cathodoluminescence (CL) spectra reveal a broad visible region covering the range from 420 to 800nm. By using room temperature-CL, we got luminescence information, especially to verify the origin of specific emissions, the internal absorption of the ultraviolet and the spatial distribution of radiative defects. It was observed that the visible wavelength range depends on the penetration depth of the excitation. This suggests that the concentration of deep levels responsible for the visible luminescence is at the sample surface to a depth of 1-2 mu m when using an accelerating voltage up to 20-30kV. The results indicate that demonstration of WLEDs on paper substrate with reasonable electrical performance greatly influences the reduction of substrate cost, furthermore, this may open way to fabricate optoelectronics devices on disposable substrates for large-area applications.

Place, publisher, year, edition, pages
Wiley-VCH Verlag, 2013
Keywords
aqueous chemical method, cathodoluminescence, light-emitting diodes, nanorods, paper, ZnO
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-102791 (URN)10.1002/pssa.201329041 (DOI)000327709700020 ()
Available from: 2014-01-07 Created: 2013-12-26 Last updated: 2017-12-06
Hussain, I., Yousuf Soomro, M., Bano, N., Nur, O. & Willander, M. (2013). Systematic study of interface trap and barrier inhomogeneities using I-V-T characteristics of Au/ZnO nanorods Schottky diode. Journal of Applied Physics, 113(23)
Open this publication in new window or tab >>Systematic study of interface trap and barrier inhomogeneities using I-V-T characteristics of Au/ZnO nanorods Schottky diode
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2013 (English)In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 113, no 23Article in journal (Refereed) Published
Abstract [en]

This paper presents in-depth analysis of I-V-T characteristics of Au/ZnO nanorods Schottky diodes. The temperature dependence I-V parameters such as the ideality factor and the barrier heights have been explained on the basis of inhomogeneity. Detailed and systematic analysis was performed to extract information about the interface trap states. The ideality factor decreases, while the barrier height increases with increase of temperature. These observations have been ascribed to barrier inhomogeneities at the Au/ZnO nanorods interface. The inhomogeneities can be described by the Gaussian distribution of barrier heights. The effect of tunneling, Fermi level pinning, and image force lowering has contribution in the barrier height lowering. The recombination-tunneling mechanism is used to explain the conduction process in Au/ZnO nanorods Schottky diodes. The ionization of interface states has been considered for explaining the inhomogeneities.

Place, publisher, year, edition, pages
American Institute of Physics (AIP), 2013
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-95963 (URN)10.1063/1.4810924 (DOI)000321011700072 ()
Available from: 2013-08-19 Created: 2013-08-12 Last updated: 2017-12-06
Soomro, M. Y., Hussain, I., Bano, N., Hussain, S., Nur, O. & Willander, M. (2012). Enhancement of zinc interstitials in ZnO nanotubes grown on glass substrate by the hydrothermal method. Applied Physics A: Materials Science & Processing, 106(1), 151-156
Open this publication in new window or tab >>Enhancement of zinc interstitials in ZnO nanotubes grown on glass substrate by the hydrothermal method
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2012 (English)In: Applied Physics A: Materials Science & Processing, ISSN 0947-8396, E-ISSN 1432-0630, Vol. 106, no 1, p. 151-156Article in journal (Refereed) Published
Abstract [en]

In this study, high density well aligned ZnO nanotubes were grown on glass via a two-step growth-then-etching by simple and template-free hydrothermal method. We used etching procedure to introduce additional zinc interstitial defects in the ZnO nanotubes. The optical properties of the ZnO nanotubes have been investigated by depth-resolved cathodluminescence spectroscopy (DRCLS) which provides information about the physical origin and growth dependence of optically active defects together with their spatial distribution. The DRCLS study gives clear evidence about the enhancement of zinc interstitial defects which are responsible for the violet and decrease of the DL emission in ZnO nanotubes when compared to the as grown ZnO nanorods. We observed a variation in the zinc interstitials along the nanotube depth.

Place, publisher, year, edition, pages
Springer Verlag (Germany), 2012
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-74648 (URN)10.1007/s00339-011-6658-8 (DOI)000298644100022 ()
Available from: 2012-02-03 Created: 2012-02-03 Last updated: 2017-08-30
Hussain, I., Soomro, M. Y., Bano, N., Nur, O. & Willander, M. (2012). Interface trap characterization and electrical properties of Au-ZnO nanorod Schottky diodes by conductance and capacitance methods. Journal of Applied Physics, 112(6), 064506
Open this publication in new window or tab >>Interface trap characterization and electrical properties of Au-ZnO nanorod Schottky diodes by conductance and capacitance methods
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2012 (English)In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 112, no 6, p. 064506-Article in journal (Refereed) Published
Abstract [en]

Schottky diodes with Au/ZnO nanorod (NR)/n-SiC configurations have been fabricated and their interface traps and electrical properties have been investigated by current-voltage (I-V), capacitance-voltage (C-V), capacitance-frequency (C-f), and conductance-frequency (G(p)/omega-omega) measurements. Detailed and systematic analysis of the frequency-dependent capacitance and conductance measurements was performed to extract the information about the interface trap states. The discrepancy between the high barrier height values obtained from the I-V and the C-V measurements was also analyzed. The higher capacitance at low frequencies was attributed to excess capacitance as a result of interface states in equilibrium in the ZnO that can follow the alternating current signal. The energy of the interface states (E-ss) with respect to the valence band at the ZnO NR surface was also calculated. The densities of interface states obtained from the conductance and capacitance methods agreed well with each other and this confirm that the observed capacitance and conductance are caused by the same physical processes, i.e., recombination-generation in the interface states. (C) 2012 American Institute of Physics.

Place, publisher, year, edition, pages
American Institute of Physics (AIP), 2012
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-85203 (URN)10.1063/1.4752402 (DOI)000309423200151 ()
Available from: 2012-11-09 Created: 2012-11-09 Last updated: 2017-12-07
Soomro, M. Y., Hussain, I., Bano, N., Broitman, E., Nur, O. & Willander, M. (2012). Nanoscale elastic modulus of single horizontal ZnO nanorod using nanoindentation experiment. Nanoscale Research Letters, 7, 146-148
Open this publication in new window or tab >>Nanoscale elastic modulus of single horizontal ZnO nanorod using nanoindentation experiment
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2012 (English)In: Nanoscale Research Letters, ISSN 1931-7573, E-ISSN 1556-276X, Vol. 7, p. 146-148Article in journal (Refereed) Published
Abstract [en]

We measure the elastic modulus of a single horizontal ZnO nanorod [NR] grown by a low-temperature hydrothermal chemical process on silicon substrates by performing room-temperature, direct load-controlled nanoindentation measurements. The configuration of the experiment for the single ZnO NR was achieved using a focused ion beam/scanning electron microscope dual-beam instrument. The single ZnO NR was positioned horizontally over a hole on a silicon wafer using a nanomanipulator, and both ends were bonded with platinum, defining a three-point bending configuration. The elastic modulus of the ZnO NR, extracted from the unloading curve using the well-known Oliver-Pharr method, resulted in a value of approximately 800 GPa. Also, we discuss the NR creep mechanism observed under indentation. The mechanical behavior reported in this paper will be a useful reference for the design and applications of future nanodevices.

Place, publisher, year, edition, pages
Springer, 2012
National Category
Ceramics Physical Sciences
Identifiers
urn:nbn:se:liu:diva-88523 (URN)10.1186/1556-276X-7-146 (DOI)000208952000001 ()22353250 (PubMedID)
Available from: 2013-02-11 Created: 2013-02-11 Last updated: 2018-07-19
Soomro, M. Y., Hussain, I., Bano, N., Nur, O. & Willander, M. (2012). Piezoelectric power generation from zinc oxide nanowires grown on paper substrate. Physica Status Solidi. Rapid Research Letters, 6(2), 80-82
Open this publication in new window or tab >>Piezoelectric power generation from zinc oxide nanowires grown on paper substrate
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2012 (English)In: Physica Status Solidi. Rapid Research Letters, ISSN 1862-6254, E-ISSN 1862-6270, Vol. 6, no 2, p. 80-82Article in journal (Refereed) Published
Abstract [en]

In this study, we demonstrate piezoelectric power generation from zinc oxide (ZnO) nanowires grown on paper substrate. Vertically aligned ZnO nanowires are deflected by an atomic force microscopy (AFM) tip in contact mode which generates an output voltage of up to 7 mV. Furthermore, the effects of different parameters mainly influencing the magnitude of the output voltage are discussed. We expect that due to its simplicity, this approach represents an important step within the development of nanoscale power generators. It offers a promising alternative powering source for the next generation of nanodevices on disposable paper.

Place, publisher, year, edition, pages
Wiley-VCH Verlag Berlin, 2012
Keywords
ZnO, nanowires, piezoelectric effects, power generation, paper substrates
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-76026 (URN)10.1002/pssr.201105519 (DOI)000300768400011 ()
Available from: 2012-03-29 Created: 2012-03-23 Last updated: 2017-08-30
Bano, N. (2011). Fabrication and Characterization of ZnO Nanorods Based Intrinsic White Light Emitting Diodes (LEDs). (Doctoral dissertation). Linköping: Linköping University Electronic Press
Open this publication in new window or tab >>Fabrication and Characterization of ZnO Nanorods Based Intrinsic White Light Emitting Diodes (LEDs)
2011 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

ZnO material based hetero-junctions are a potential candidate for the design andrealization of intrinsic white light emitting devices (WLEDs) due to several advantages overthe nitride based material system. During the last few years the lack of a reliable andreproducible p-type doping in ZnO material with sufficiently high conductivity and carrierconcentration has initiated an alternative approach to grow n-ZnO nanorods (NRs) on other ptypeinorganic and organic substrates. This thesis deals with ZnO NRs-hetero-junctions basedintrinsic WLEDs grown on p-SiC, n-SiC and p-type polymers. The NRs were grown by thelow temperature aqueous chemical growth (ACG) and the high temperature vapor liquid solid(VLS) method. The structural, electrical and optical properties of these WLEDs wereinvestigated and analyzed by means of scanning electron microscope (SEM), current voltage(I-V), photoluminescence (PL), cathodoluminescence (CL), electroluminescence (EL) anddeep level transient spectroscopy (DLTS). Room temperature (RT) PL spectra of ZnOtypically exhibit one sharp UV peak and possibly one or two broad deep level emissions(DLE) due to deep level defects in the bandgap. For obtaining detailed information about thephysical origin, growth dependence of optically active defects and their spatial distribution,especially to study the re-absorption of the UV in hetero-junction WLEDs structure depthresolved CL spectroscopy, is performed. At room temperature the CL intensity of the DLEband is increased with the increase of the electron beam penetration depth due to the increaseof the defect concentration at the ZnO NRs/substrate interface. The intensity ratio of the DLEto the UV emission, which is very useful in exploring the origin of the deep level emissionand the distribution of the recombination centers, is monitored. It was found that the deepcenters are distributed exponentially along the ZnO NRs and that there are more deep defectsat the root of ZnO NRs compared to the upper part. The RT-EL spectra of WLEDs illustrateemission band covering the whole visible range from 420 nm and up to 800 nm. The whitelightcomponents are distinguished using a Gaussian function and the components were foundto be violet, blue, green, orange and red emission lines. The origin of these emission lines wasfurther identified. Color coordinates measurement of the WLEDs reveals that the emitted lighthas a white impression. The color rendering index (CRI) and the correlated color temperature(CCT) of the fabricated WLEDs were calculated to be 80-92 and 3300-4200 K, respectively.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2011. p. 68
Series
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 1401
Keywords
Zinc Oxide nanorods, White light emitting diode, Photoluminescence, Cathodoluminescence, Electroluminescence, Deep level transient spectroscopy (DLTS)
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-71829 (URN)978-91-7393-054-3 (ISBN)
Public defence
2011-11-11, K3, Kåkenhus, Campus Norrköping, Linköpings universitet, Norrköping, 10:15 (English)
Opponent
Supervisors
Available from: 2011-11-07 Created: 2011-11-07 Last updated: 2014-01-15Bibliographically approved
Willander, M., Nur, O., Zaman, S., Zainelabdin, A., Amin, G., Jamil Rana, S., . . . Alvi, N. u. (2011). Intrinsic White Light Emission from Zinc Oxide Nanorods Heterojunctions on Large Area Substrates. In: Ferechteh Hosseini Teherani, David C. Look, David J. Rogers (Ed.), Proceedings of SPIE Volume 7940. Paper presented at Conference on Oxide-based Materials and Devices II, San Francisco, CA, USA, JAN 23-26, 2011. Bellingham, Washington, USA: SPIE - International Society for Optical Engineering
Open this publication in new window or tab >>Intrinsic White Light Emission from Zinc Oxide Nanorods Heterojunctions on Large Area Substrates
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2011 (English)In: Proceedings of SPIE Volume 7940 / [ed] Ferechteh Hosseini Teherani, David C. Look, David J. Rogers, Bellingham, Washington, USA: SPIE - International Society for Optical Engineering, 2011Conference paper, Published paper (Other academic)
Abstract [en]

Zinc oxide (ZnO) and especially in the nanostructure form is currently being intensively investigated world wide for the possibility of developing different new photonic devices. We will here present our recent findings on the controlled low temperature chemical growth of ZnO nanorods (NRs) on different large area substrates. Many different heterojunctions of ZnO NRs and p-substrates including those of crystalline e. g. p-GaN, p-SiC or amorphous nature e. g. p-polymer coated plastic and p-polymer coated paper will be shown. Moreover, the effect of the p-electrode of these heterojunctions on tuning the emitted wavelength and changing the light quality will be discussed. An example using ZnO NR/p-GaN will be shown and the electrical and electro-optical characteristics will be analyzed. For these heterojunctions the effect of post growth annealing and its effect on the electroluminescence (EL) spectrum will be shown. Finally, intrinsic white light emitting diodes based on ZnO NRs on foldable and disposable amorphous substrates (plastic and paper) will also be presented.

Place, publisher, year, edition, pages
Bellingham, Washington, USA: SPIE - International Society for Optical Engineering, 2011
Series
Proceedings of SPIE, ISSN 0277-786X ; 7940
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-74726 (URN)10.1117/12.879327 (DOI)9780819484772 (ISBN)
Conference
Conference on Oxide-based Materials and Devices II, San Francisco, CA, USA, JAN 23-26, 2011
Available from: 2012-02-06 Created: 2012-02-06 Last updated: 2017-02-23Bibliographically approved
Hussain, I., Bano, N., Hussain, S., Nur, O. & Willander, M. (2011). Study of intrinsic white light emission and its components from ZnO-nanorods/p-polymer hybrid junctions grown on glass substrates. Journal of Materials Science, 46(23), 7437-7442
Open this publication in new window or tab >>Study of intrinsic white light emission and its components from ZnO-nanorods/p-polymer hybrid junctions grown on glass substrates
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2011 (English)In: Journal of Materials Science, ISSN 0022-2461, E-ISSN 1573-4803, Vol. 46, no 23, p. 7437-7442Article in journal (Refereed) Published
Abstract [en]

We report white-light luminescence from ZnO-organic hybrid light emitting diodes grown on glass substrate by low temperature aqueous chemical growth. The configuration used for the hybrid white light emitting diodes (HWLEDs) consists of two-layers of polymers (PEDOT:PSS/PFO) on glass with top ZnO nanorods. Electroluminescence spectra of the HWLEDs demonstrate the combination of emission bands arising from the radiative recombination in polymer and ZnO nanorods. In order to distinguish emission bands we used a Gaussian function to simulate the experimental data. The emitted white light was found to be the superposition of a blue line at 454 nm, a green emission at 540 nm, orange line at 617 nm, and finally a red emission at 680 nm. The transitions causing these emissions are identified and discussed in terms of the energy band diagram of the hybrid junction. Color coordinates measurement of the WLED reveals that the emitted light has a white impression with 70 color rendering index and correlated color temperature 5500 K. Comparison between ITO and aluminum top contacts and its influence on the emitted intensity is also discussed.

Place, publisher, year, edition, pages
Springer Verlag (Germany), 2011
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-71543 (URN)10.1007/s10853-011-5708-0 (DOI)000295179700011 ()
Available from: 2011-10-21 Created: 2011-10-21 Last updated: 2017-12-08Bibliographically approved
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