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Sample records for al-doped zno thin

  1. Thermoelectric Properties of Al-Doped Mesoporous ZnO Thin Films

    OpenAIRE

    Min-Hee Hong; Chang-Sun Park; Won-Seon Seo; Young Soo Lim; Jung-Kun Lee; Hyung-Ho Park

    2013-01-01

    Al-doped mesoporous ZnO thin films were synthesized by a sol-gel process and an evaporation-induced self-assembly process. In this work, the effects of Al doping concentration on the electrical conductivity and characterization of mesoporous ZnO thin films were investigated. By changing the Al doping concentration, ZnO grain growth is inhibited, and the mesoporous structure of ZnO is maintained during a relatively high temperature annealing process. The porosity of Al-doped mesoporous ZnO thi...

  2. Thermoelectric Properties of Al-Doped Mesoporous ZnO Thin Films

    Directory of Open Access Journals (Sweden)

    Min-Hee Hong

    2013-01-01

    Full Text Available Al-doped mesoporous ZnO thin films were synthesized by a sol-gel process and an evaporation-induced self-assembly process. In this work, the effects of Al doping concentration on the electrical conductivity and characterization of mesoporous ZnO thin films were investigated. By changing the Al doping concentration, ZnO grain growth is inhibited, and the mesoporous structure of ZnO is maintained during a relatively high temperature annealing process. The porosity of Al-doped mesoporous ZnO thin films increased slightly with increasing Al doping concentration. Finally, as electrical conductivity was increased as electrons were freed and pore structure was maintained by inhibiting grain growth, the thermoelectric property was enhanced with increasing Al concentration.

  3. Semiconducting properties of Al doped ZnO thin films.

    Science.gov (United States)

    Al-Ghamdi, Ahmed A; Al-Hartomy, Omar A; El Okr, M; Nawar, A M; El-Gazzar, S; El-Tantawy, Farid; Yakuphanoglu, F

    2014-10-15

    Aluminum doped ZnO (AZO) thin films were successfully deposited via spin coating technique onto glass substrates. Structural properties of the films were analyzed by X-ray diffraction, atomic force microscopy (AFM) and energy dispersive X-ray spectroscopy. X-ray diffraction results reveal that all the films are polycrystalline with a hexagonal wurtzite structure with a preferential orientation according to the direction (002) plane. The crystallite size of ZnO and AZO films was determined from Scherrer's formula and Williamson-Hall analysis. The lattice parameters of the AZO films were found to decrease with increasing Al content. Energy dispersive spectroscopy (EDX) results indicate that Zn, Al and O elements are present in the AZO thin films. The electrical conductivity, mobility carriers and carrier concentration of the films are increased with increasing Al doping concentration. The optical band gap (Eg) of the films is increased with increasing Al concentration. The AZO thin films indicate a high transparency in the visible region with an average value of 86%. These transparent AZO films may be open a new avenue for optoelectronic and photonic devices applications in near future.

  4. Elaboration and characterization of Al doped ZnO nanorod thin films annealed in hydrogen

    Energy Technology Data Exchange (ETDEWEB)

    Zhong Wenwu [Department of Physics, School of Physics and Nuclear Energy Engineering, Key Laboratory of Micro-nano Measurement-Manipulation and Physics (Ministry of Education), Beijing University of Aeronautics and Astronautics, Beijing 100191 (China); Liu Famin, E-mail: fmliu@buaa.edu.cn [Department of Physics, School of Physics and Nuclear Energy Engineering, Key Laboratory of Micro-nano Measurement-Manipulation and Physics (Ministry of Education), Beijing University of Aeronautics and Astronautics, Beijing 100191 (China); Cai Lugang; Peng Ding; Zhou Chuancang; Zeng Legui [Department of Physics, School of Physics and Nuclear Energy Engineering, Key Laboratory of Micro-nano Measurement-Manipulation and Physics (Ministry of Education), Beijing University of Aeronautics and Astronautics, Beijing 100191 (China); Liu Xuequan; Li Yi [Central Iron and Steel Research Institute, Beijing 100081 (China)

    2011-03-03

    Research highlights: > High transparent and conductive Al doped ZnO nanorod thin films were synthesized using sol-gel spin-coating method. > Al doped ZnO nanorod thin films can be got by annealing in hydrogen rather than in air. > Crystal orientation of Al doped ZnO thin film has been raised. > Resistivity of films has been remarkably reduced by annealing in hydrogen. - Abstract: ZnO thin films doped with Al concentrations of 1.0, 2.0, 3.0, 4.0, 5.0 at% were prepared by a sol-gel spin-coating method on glass substrates and respectively annealed at 550 deg. C for 2 h in hydrogen and air. The X-ray diffraction and selected-area electron diffraction results confirm that the Al doped ZnO thin films are of wurtzite hexagonal ZnO. The scanning electron microscope results indicate that the Al doped ZnO nanorod thin films can be got by annealing in hydrogen rather than in air. The optical properties reveal that the Al doped ZnO thin films have obviously enhanced transmittance in the visible region. The electrical properties show that the resistivity of 1.0 at% Al doped ZnO thin films has been remarkably reduced from 0.73 {Omega} m by annealing in air to 3.2 x 10{sup -5} {Omega} m by annealing in hydrogen. It is originated that the Al doped ZnO nanorod thin films annealed in hydrogen increased in electron concentration and mobility due to the elimination of adsorbed oxygen species, and multicoordinated hydrogen.

  5. Atomic layer deposition of Al-doped ZnO thin films

    OpenAIRE

    Tynell, Tommi; Yamauchi, Hisao; Karppinen, Maarit; Okazaki, Ryuji; Terasaki, Ichiro

    2013-01-01

    Atomic layer deposition has been used to fabricate thin films of aluminum-doped ZnO by depositing interspersed layers of ZnO and Al 2O3 on borosilicate glass substrates. The growth characteristics of the films have been investigated through x-ray diffraction, x-ray reflection, and x-ray fluorescence measurements, and the efficacy of the Al doping has been evaluated through optical reflectivity and Seebeck coefficient measurements. The Al doping is found to affect the carrier density of ZnO up...

  6. Atomic layer deposition of Al-doped ZnO thin films

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    Tynell, Tommi; Yamauchi, Hisao; Karppinen, Maarit; Okazaki, Ryuji; Terasaki, Ichiro [Department of Chemistry, Aalto University, FI-00076 Aalto (Finland); Department of Physics, Nagoya University, Nagoya 464-8602 (Japan)

    2013-01-15

    Atomic layer deposition has been used to fabricate thin films of aluminum-doped ZnO by depositing interspersed layers of ZnO and Al{sub 2}O{sub 3} on borosilicate glass substrates. The growth characteristics of the films have been investigated through x-ray diffraction, x-ray reflection, and x-ray fluorescence measurements, and the efficacy of the Al doping has been evaluated through optical reflectivity and Seebeck coefficient measurements. The Al doping is found to affect the carrier density of ZnO up to a nominal Al dopant content of 5 at. %. At nominal Al doping levels of 10 at. % and higher, the structure of the films is found to be strongly affected by the Al{sub 2}O{sub 3} phase and no further carrier doping of ZnO is observed.

  7. Synthesis and conductivity enhancement of Al-doped ZnO nanorod array thin films.

    Science.gov (United States)

    Hsu, Chih-Hsiung; Chen, Dong-Hwang

    2010-07-16

    Al-doped ZnO (AZO) nanorod array thin films with various Al/Zn molar ratios were synthesized by chemical bath deposition. The resultant AZO nanorods were well-aligned at the glass substrate, growing vertically along the c-axis [001] direction. In addition, they had an average diameter of 64.7 +/- 16.8 nm and an average length of about 1.0 microm with the structure of wurtzite-type ZnO. Analyses of energy dispersive x-ray spectra and x-ray photoelectron spectra indicated that Al atoms had been doped into the ZnO crystal lattice. The doping of Al atoms did not result in significant changes in the structure and crystal orientation, but the electrical resistivity was found to increase first and then decrease with increasing Al content owing to the increase of carrier concentration and the decrease of mobility. In addition, the transmission in the visible region increased but the increase was reduced at higher Al doping levels. After hydrogen treatment, the morphology of the AZO nanorod array thin films remained unchanged. However, the electrical resistivity decreased significantly due to the formation of oxygen vacancies and interstitial hydrogen atoms. When the real Al/Zn molar ratio was about 3.7%, the conductivity was enhanced about 1000 times and a minimum electrical resistivity of 6.4 x 10( - 4) Omega cm was obtained. In addition, the transmission of the ZnO nanorod array thin film in the visible region was significantly increased but the increase was less significant for the AZO nanorod array thin film, particularly at higher Al doping levels. In addition, the current-voltage curves of the thin film devices with ZnO or AZO nanorod arrays revealed that AZO had a higher current response than ZnO and hydrogen treatment led to a more significant enhancement of current responses (about 100-fold).

  8. Formation of Al-doped ZnO thin films on glass by sol-gel process and characterization

    Science.gov (United States)

    Shahid, M. U.; Deen, K. M.; Ahmad, A.; Akram, M. A.; Aslam, M.; Akhtar, W.

    2016-02-01

    In this study, pure ZnO and Al-doped ZnO thin films were developed on glass by sol-gel process followed by drying and annealing in air at 170 and 400 °C, respectively. The surface morphology and structural characteristics were determined through scanning electron microscopy, atomic force microscopy and X-ray diffraction. The Fourier transform infrared spectroscopy validated the formation of Al-doped ZnO film on glass substrate. It was evaluated that 1 at% aluminum (Al) doping in ZnO film showed low electrical resistivity and higher charge carrier concentration due to uniformly dispersed regular shape crystallites as compared to pure ZnO and 2 at% `Al'-doped thin films.

  9. Pulsed laser deposited Al-doped ZnO thin films for optical applications

    Directory of Open Access Journals (Sweden)

    Gurpreet Kaur

    2015-02-01

    Full Text Available Highly transparent and conducting Al-doped ZnO (Al:ZnO thin films were grown on glass substrates using pulsed laser deposition technique. The profound effect of film thickness on the structural, optical and electrical properties of Al:ZnO thin films was observed. The X-ray diffraction depicts c-axis, plane (002 oriented thin films with hexagonal wurtzite crystal structure. Al-doping in ZnO introduces a compressive stress in the films which increase with the film thickness. AFM images reveal the columnar grain formation with low surface roughness. The versatile optical properties of Al:ZnO thin films are important for applications such as transparent electromagnetic interference (EMI shielding materials and solar cells. The obtained optical band gap (3.2–3.08 eV was found to be less than pure ZnO (3.37 eV films. The lowering in the band gap in Al:ZnO thin films could be attributed to band edge bending phenomena. The photoluminescence spectra gives sharp visible emission peaks, enables Al:ZnO thin films for light emitting devices (LEDs applications. The current–voltage (I–V measurements show the ohmic behavior of the films with resistivity (ρ~10−3 Ω cm.

  10. Growth, structure and optical characterization of Al-doped ZnO nanoparticle thin films

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    Prajapati, C.S.; Sahay, P.P. [Department of Physics, Motilal Nehru National Institute of Technology, Allahabad (India)

    2011-10-15

    Al-doped ZnO nanoparticle thin films were prepared on glass substrate at the optimum temperature of (410{+-}10) C by spray pyrolysis technique using zinc nitrate as a precursor solution and aluminium chloride as a dopant. The dopant concentration (Al/Zn at%) was varied from 0 to 2 at%. Structural analysis of the films shows that all the films are of polycrystalline zinc oxide in nature, possessing hexagonal wurtzite structure. The films exhibit variation in peak intensities corresponding to (100), (002) and (101) reflection planes on Al-doping. The crystallite size calculated by Scherrer formula has been found to be in the range of 35-65 nm. The optical absorption study shows that the optical band gap in the Al-doped films varies in the range of 3.11 - 3.22 eV. The width of localized states in the band gap estimated by the Urbach tail analysis has been found to be minimum in case of the 1 at% Al-doped zinc oxide thin film. (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  11. Al-doped and in-doped ZnO thin films in heterojunctions with silicon

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    Chabane, L.; Zebbar, N.; Kechouane, M. [LCMS, Faculty of Physics, University of Sciences and Technology (USTHB), BP 32-16111, Algiers (Algeria); Aida, M.S. [LCMet Interface, Faculty of Sciences, University of Constantine, 25000 (Algeria); Trari, M. [Laboratory of Storage and Valorization of Renewable Energies, Faculty of Chemistry (USTHB), BP 32-16111 Algiers (Algeria)

    2016-04-30

    The undoped, Al-doped and In-doped ZnO thin films were deposited by ultrasonic spray pyrolysis technique, onto glass and p-Si substrates and the physical properties of the films were investigated. The X-ray diffraction, optical analysis and electrical characterisations, indicate that the films were polycrystalline with hexagonal würtzite type structure and revealed that the aluminium doping deteriorates the crystalline and optical properties and enhances the electrical conductivity whereas indium doping improves all properties. The transport mechanism controlling the conduction through the heterojunctions was studied. For the heterostructures, the temperature dependent current–voltage characteristics showed rectifying behaviour in the dark, but current transport mechanism is not the same for all heterojunctions. Therefore, the presence of the interface states and volume defects are identified as limiting factors for obtaining a high quality heterojunction interface. - Highlights: • Al-doped and In-doped ZnO thin films have been deposited onto Si. • In-doped ZnO/p-Si heterojunction showed poor rectifying behaviour. • Al-doped ZnO/p-Si heterojunction showed a good rectifying at room temperature. • The carriers transport mechanisms was controlled by interfacial and volume defects.

  12. Al-doped ZnO Thin Films for Ethanol Sensors

    Science.gov (United States)

    Nulhakim, Lukman; Nugraha; Nuruddin, Ahmad; Suyatman; Yuliarto, Brian

    2011-12-01

    Al doped ZnO (AZO) is done to understand the effect of Al dopant on ZnO. The sensor response condition will be analyzed for ethanol detection. Chemical Bath Deposition (CBD) method is used to fabrication pure ZnO and AZO thin films. Al dopant concentrations used in this study is 2.9 at% Al. The crystallinity, composition and morphology were investigated by using XRD, EDS and SEM. The ZnO and AZO gas sensors were exposed to different concentrations of ethanol at room temperature, 2.5%, 5% and 7.5% volume ethanol, respectively. The sensor response at low concentrations (2.5% V) for pure ZnO sample is 70.88% and 88.57% for high concentrations of ethanol (7.5% V). The highest sensor response for AZO sample is 95.29% at low concentrations (2.5% V) and 96.68% V at the high concentration (7.5% V).

  13. Preparation and characterization of sol-gel Al-doped ZnO thin films and ZnO nanowire arrays grown on Al-doped ZnO seed layer by hydrothermal method

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    Zhang, Jin; Que, Wenxiu [Electronic Materials Research Laboratory, School of Electronic and Information Engineering, Xi' an, Jiaotong University, Xi' an 710049, Shaanxi (China)

    2010-12-15

    Al-doped ZnO (AZO) nanocrystalline thin films are prepared by a sol-gel technique. Effects of the Al-doped concentration on microstructural, electrical and optical properties of the AZO thin films are studied and discussed. Results indicate that the AZO crystalline thin film with a highly preferred c-axis orientation perpendicular to the substrate is grown, and the AZO thin film with a small crystal grain size of 30-40 nm, high transmittance of above 90% in visible region, and low resistivity of 1.9 x 10{sup -2} {omega} cm can be obtained when the Al-doped concentration is up to 1 at%. Furthermore, ZnO nanowire (ZnO NW) arrays with a large surface area are grown on the sol-gel derived AZO thin film, which acts as a seed layer, by using a hydrothermal method. Optical properties of the grown ZnO NW arrays reveal that a high transmittance in visible region can be obtained, and only a strong UV emission at about 380 nm is observed in the room-temperature photoluminescence spectra, which implies that few crystal defects exist inside the as-assembled ZnO NW arrays. (author)

  14. Effect of heat treatment on microstructural and optical properties of CBD grown Al-doped ZnO thin films

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    Chandramohan, R., E-mail: rathinam.chandramohan@gmail.com [Department of Physics, Sree Sevugan Annamalai College, College Road, Devakottai 630303 (India); Vijayan, T.A. [Department of Physics, Sree Sevugan Annamalai College, College Road, Devakottai 630303 (India); Arumugam, S.; Ramalingam, H.B. [Department of Physics, Government Arts College, Udumalpet 642126 (India); Dhanasekaran, V.; Sundaram, K.; Mahalingam, T. [Department of Physics, Alagappa University, Karaikudi 630003 (India)

    2011-02-15

    Research highlights: > Effect of annealing temperature on Al-doped ZnO thin films. > Microstructural properties of Al-doped ZnO thin films. > Optical constants are found to increase with increase of heat treatment. - Abstract: Investigations on the effect of annealing temperature on the structural, optical properties and morphology of Al-doped ZnO thin films deposited on glass substrate by chemical bath deposition have been carried out. X-ray diffraction studies revealed that deposited films are in polycrystalline nature with hexagonal structure along the (0 0 2) crystallographic plane. Microstructural properties of films such as crystallite size, texture coefficient, stacking fault probability and microstrain were calculated from predominant (0 0 2) diffraction lines. The UV-Vis-NIR spectroscopy studies revealed that all the films have high optical transmittance (>60%) in the visible range. The optical band gap values are found to be in the range of 3.25-3.31 eV. Optical constants have been estimated and the values of n and k are found to increase with increase of heat treatment. The films have increased transmittance with increase of heat treatment. Al-doped ZnO thin films fabricated by this simple and economic chemical bath deposition technique without using any carrier gas are found to be good in structural and optical properties which are desirable for photovoltaic applications. Scanning electron microscopic images revealed that the hexagonal shaped grains that occupy the entire surface of the film with its near stoichiometric composition.

  15. Work function increase of Al-doped ZnO thin films by B+ ion implantation.

    Science.gov (United States)

    Hong, Sang-Jin; Heo, Gi-Seok; Park, Jong-Woon; Lee, In-Hwan; Choi, Bum-Ho; Lee, Jong-Ho; Park, Se-Yeon; Shin, Dong-Chan

    2007-11-01

    The work function of an Al-doped ZnO (AZO) thin film can be increased via B+ ion implantation from 3.92 eV up to 4.22 eV. The ion implantation has been carried out with the ion dose of 1 x 10(16) cm(-2) and ion energy of 5 keV. The resistance of the B+ implanted AZO films has been a bit raised, while their transmittance is slightly lowered, compared to those of un-implanted AZO films. These behaviors can be explained by the doping profile and the resultant band diagram. It is concluded that the coupling between the B+ ions and oxygen vacancies would be the main reason for an increase in the work function and a change in the other properties. We also address that the work function is more effectively alterable if the defect density of the top transparent conducting oxide layer can be controlled.

  16. Sol-gel synthesis and characterization of undoped and Al-doped ZnO thin films for memristive application

    Directory of Open Access Journals (Sweden)

    Dawit G. Ayana

    2016-11-01

    Full Text Available The Sol-gel route is a versatile method to fabricate multi-layer, dense and homogeneous ZnO thin films with a controlled thickness and defects for a memristive application. In this work, sol-gel derived multi-layer undoped and Al-doped ZnO thin films were prepared by a spin-coating technique on SiO2/Ti/Pt and silica glass substrates. The effect of both Al doping and curing conditions on the structural and morphological features of ZnO films was investigated by complementary techniques, including electron microscopy, atomic force microscopy, X-ray photoelectron spectroscopy, micro-Raman spectroscopy, and X-ray diffraction analysis. Electrical measurements were performed on SiO2/Ti/Pt/ZnO/Pt(dishes and SiO2/Ti/Pt/ZnO(Al/Pt(dishes fabricated memristive cells and preliminary current-voltage curves were acquired.

  17. Sol-gel synthesis and characterization of undoped and Al-doped ZnO thin films for memristive application

    Science.gov (United States)

    Ayana, Dawit G.; Prusakova, Valentina; Collini, Cristian; Nardi, Marco V.; Tatti, Roberta; Bortolotti, Mauro; Lorenzelli, Leandro; Chiappini, Andrea; Chiasera, Alessandro; Ferrari, Maurizio; Lunelli, Lorenzo; Dirè, Sandra

    2016-11-01

    The Sol-gel route is a versatile method to fabricate multi-layer, dense and homogeneous ZnO thin films with a controlled thickness and defects for a memristive application. In this work, sol-gel derived multi-layer undoped and Al-doped ZnO thin films were prepared by a spin-coating technique on SiO2/Ti/Pt and silica glass substrates. The effect of both Al doping and curing conditions on the structural and morphological features of ZnO films was investigated by complementary techniques, including electron microscopy, atomic force microscopy, X-ray photoelectron spectroscopy, micro-Raman spectroscopy, and X-ray diffraction analysis. Electrical measurements were performed on SiO2/Ti/Pt/ZnO/Pt(dishes) and SiO2/Ti/Pt/ZnO(Al)/Pt(dishes) fabricated memristive cells and preliminary current-voltage curves were acquired.

  18. Exploration of Al-Doped ZnO in Photovoltaic Thin Films

    Science.gov (United States)

    Ciccarino, Christopher; Sahiner, M. Alper

    The electrical properties of Al doped ZnO-based thin films represent a potential advancement in the push for increasing solar cell efficiency. Doping with Aluminum will theoretically decrease resistivity of the film and therefore achieve this potential as a viable option in the P-N junction phase of photovoltaic cells. The n-type semi-conductive characteristics of the ZnO layer will theoretically be optimized with the addition of Aluminum carriers. In this study, Aluminum doping concentrations ranging from 1-3% by mass were produced, analyzed, and compared. Films were developed onto ITO coated glass using the Pulsed Laser Deposition technique. Target thickness was 250 nm and ellipsometry measurements showed uniformity and accuracy in this regard. Active dopant concentrations were determined using Hall Effect measurements. Efficiency measurements showed possible applications of this doped compound, with upwards of 7% efficiency measured, using a Keithley 2602 SourceMeter set-up. XRD scans showed highly crystalline structures, with effective Al intertwining of the hexagonal wurtzile ZnO molecular structure. This alone indicates a promising future of collaboration between these two materials.

  19. Effect of RF power on an Al-doped ZnO thin film deposited by RF magnetron sputtering

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    Kim, Jong-Wook; Kim, Hong-Bae [Cheongju University, Cheongju (Korea, Republic of); Kim, Deok-Kyu [Samsung LED Co. Ltd., Suwon (Korea, Republic of)

    2011-09-15

    Transparent and conductive Al-doped ZnO thin films (thickness: 200 nm) were prepared on glass substrates via RF magnetron sputtering at room temperature by using a disk of ZnO mixed with 2-wt% Al{sub 2}O{sub 3} as a target (diameter: 3 in). We investigated the effects of RF power (20 - 100 W in steps of 20 W) on the structural, optical, and electrical properties of the fabricated thin films. The preferred orientation was observed on the (002) plane of all the Al-doped ZnO thin films deposited on the glass substrates. Moreover, good crystallinity was obtained in the RF power range of 40 - 80 W. All the Al-doped ZnO thin films exhibited more than 80% transmittance, regardless of the RF power; the optical band gap increased with the RF power. The best electrical properties were obtained at 80 W as follows: electrical resistivity = 1.76 x 10{sup -3} {Omega}cm, carrier concentration = 6.35 x 10{sup 20} cm{sup -3}, and mobility = 5.57 cm{sup 2} V{sup -1} s{sup -1}. The results of X-ray photoelectron spectroscopy (XPS) analysis showed that the number of O vacancies and Al atoms depended on the RF power and that they were maximum at 80 W.

  20. Optical parameters of Al-doped ZnO nanorod array thin films grown via the hydrothermal method.

    Science.gov (United States)

    Kim, Soaram; Kim, Min Su; Nam, Giwoong; Park, Hyunggil; Yoon, Hyunsik; Leem, Jae-Young

    2013-09-01

    ZnO seed layers were deposited onto a quartz substrate using the sol--gel method, and Al-doped ZnO (AZO) nanorod array thin films with different Al concentrations that ranged from 0 to 2.0 at. % were grown on the ZnO seed layers via the hydrothermal method. Optical parameters, including the optical band gap, the absorption coefficient, the Urbach energy, the refractive index, the dispersion parameter, and the optical conductivity, were studied to investigate the effects of Al doping on the optical properties of AZO nanorod array thin films. The optical band gaps of the ZnO and AZO nanorod array thin films were 3.206 at 0 at.%, 3.214 at 0.5 at.%, 3.226 at 1.5 at.%, and 3.268 at 2.0 at.%. The Urbach energy gradually decreased from 126 meV (0 at.%) to 70 meV (2.0 at.%) as the Al concentration was increased. The dispersion energy, the single-oscillator energy, the average oscillator wavelength, the average oscillator strength, the refractive index, and the optical conductivity of the AZO nanorod array thin films were all affected by Al doping.

  1. Tailoring Energy Bandgap of Al Doped ZnO Thin Films Grown by Vacuum Thermal Evaporation Method.

    Science.gov (United States)

    Vyas, Sumit; Singh, Shaivalini; Chakrabarti, P

    2015-12-01

    The paper presents the results of our experimental investigation pertaining to tailoring of energy bandgap and other associated characteristics of undoped and Al doped ZnO (AZO) thin film by varying the atomic concentration of Al in ZnO. Thin films of ZnO and ZnO doped with Al (1, 3, and 5 atomic percent (at.%)) were deposited on silicon substrate for structural characterization and on glass substrate for optical characterization. The dependence of structural and optical properties of Al doped ZnO on the atomic concentration of Al added to ZnO has been reported. On the basis of the experimental results an empirical formula has been proposed to calculate the energy bandgap of AZO theoretically in the range of 1 to 5 at.% of Al. The study revealed that AZO films are composed of smaller and larger number of grains as compared to pure ZnO counterpart and density of the grains was found to increase as the Al concentration increased (from 1 to 5 at.%). The transmittance in the visible region was greater than 90% and found to increase with increasing Al concentration up to 5 at.%. The optical bandgap was found to increase initially with increase in atomic concentration of Al concentration up to 3 at.% and decrease thereafter with increasing concentration of Al.

  2. Laser-induced lateral voltage in epitaxial Al-doped ZnO thin films on tilted sapphire

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    Wang, Shufang; Chen, Mingjing; Yu, Wei; Chen, Jingchun; Wang, Jianglong; Fu, Guangsheng [Hebei University, College of Physics Science and Technology, Baoding (China); Zhao, Kun; Zhao, Songqing [Chinese University of Petroleum, Department of Mathematics and Physics, Beijing (China)

    2011-06-15

    Laser-induced voltage effects in epitaxial Al-doped ZnO thin films on tilted sapphire have been experimentally studied at room temperature. An open-circuit lateral voltage signal with nanosecond response time was observed when the film surface was irradiated by laser pulses of 308 nm and 1064 nm, and the voltage responsivity of the signal for 308-nm irradiation is much higher than that for 1064-nm irradiation. A mechanism based on the thermoelectric effect is proposed to explain the origin of the laser-induced lateral voltage in this system. The result suggests that the Al-doped ZnO thin films have a potential application in wide-band photodetectors from ultraviolet to near infrared. (orig.)

  3. Photoluminescence properties of defect emissions in Al-doped ZnO nanorod array thin films.

    Science.gov (United States)

    Kim, Soaram; Nam, Giwoong; Park, Hyunggil; Yoon, Hyunsik; Kim, Min Su; Kim, Do Yeob; Kim, Sung-O; Leem, Jae-Young

    2013-09-01

    The power- and temperature-dependent photoluminescence properties of Al-doped ZnO nanorod array thin films grown by the hydrothermal method were investigated. The intensities of both the near-band-edge emission (NBE) and deep-level emission (DLE) as well as the overall spectral line shape were strongly affected by the excitation power. At low excitation power, the blue emission was found to show the highest intensity among the different emission lights. A low-temperature photoluminescence analysis revealed the bound-exciton-related luminescence peak at 3.362 eV. The dependence of peak energy with the excitation power indicates that these DLE processes are generated by DAP transitions. The overall intensity of DLE was found to decrease as the temperature increases. With regard to the blue emission (around 2.52 eV), it showed a well-pronounced shoulder at 200 K. The activation energy for this blue emission was 51.93 meV, which corresponds to the thermal dissociation energy required for the donor-acceptor pair transitions.

  4. Laser induced photoconductivity in sol–gel derived Al doped ZnO thin films

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    Eskandari, F.; Ranjbar, M., E-mail: ranjbar@cc.iut.ac.ir; Kameli, P.; Salamati, H.

    2015-11-15

    In this paper Al doped ZnO (AZO) thin films with 0, 3, 6 and 12 at. % Al concentration were prepared by sol–gel method on glass substrates. The deposited films were annealed at different temperatures of 300, 350, 400, 450 and 500 °C for 1 h in air. X-ray diffraction (XRD) showed wurtzite crystalline structure for the films annealed above 400 °C. The films were subsequently irradiated by beams of excimer (KrF, λ = 248 nm) laser. The evolution of crystal structure, surface morphology and optical properties were studied using XRD, filed emission scanning electron microscope (FE-SEM) and UV–Vis spectrophotometer, respectively. Real-time measurement of electrical conductivity during laser irradiation showed a transient or persistent photoconductivity effect. The effect of laser energy on this photoconductivity was also investigated. Based on the observed photoluminescence (PL) and X-ray photoelectron spectroscopy (XPS), the observed photoconductivity effect was described. - Highlights: • AZO (0–12 at. % Al) films were prepared by sol–gel method and annealed at different temperatures. • Excimer laser (λ = 248 nm) irradiation leads to improvement of crystalline structure. • Average optical transmission doesn't change and optical gap decreases by irradiation. • Photoconductivity was investigated by real-time measurement of electrical resistance. • Sample of 6% Al annealed at 450–500 °C showed the best photoconductivity effect.

  5. Using the hydrothermal method to grow p-type ZnO nanowires on Al-doped ZnO thin film to fabricate a homojunction diode.

    Science.gov (United States)

    Tseng, Yung-Kuan; Hung, Meng-Chun; Su, Shun-Lung; Li, Sheng-Kai

    2014-10-01

    In this study, the hydrothermal method is used to grow phosphorus-doped ZnO nanowires on Si/SiO2 substrates deposited with Al-doped ZnO thin film. This structure forms a homogeneous p-n junction. In this study, we are the pioneers to use ammonium hypophosphite (NH4H2PO2) as a source of phosphorus to prepare the precursor solution. Ammonium hypophosphite of different concentration levels is used to observe its effects on the growth of nanowires. The results show that the precursor solution prepared from ammonium hypophosphite can produce good crystalline ZnO nanowires while there is no linear relationship between the amounts and concentration levels of phosphorus doped into the nanowires. Whether the phosphorus-doped ZnO nanowires have the characteristics of a p-type semiconductor is indirectly verified by measuring whether the p-n junction made up of Al-doped ZnO thin film and phosphorus-doped ZnO nanowires shows rectifying behavior. I-V measurements are made on the specimens. The results show good rectifying behavior, proving that the phosphorus-doped ZnO nanowires and Al-doped AZO films have p-type and n-type semiconductor properties, constituting a good p-n junction. This result also proves that ammonium hypophosphite is a better source of phosphorus in the hydrothermal method to synthesize phosphorus-doped ZnO nanowires.

  6. Effect of annealing treatment on the structural, optical, and electrical properties of Al-doped ZnO thin films

    Institute of Scientific and Technical Information of China (English)

    LI Li; FANG Liang; CHEN Ximing; LIU Gaobin; LIU Jun; YANG Fengfan; FU Guangzong; KONG Chunyang

    2007-01-01

    Highly conductive and transparent Al-doped ZnO (AZO) thin films were prepared from a zinc target containing Al (1.5 wt.%) by direct current (DC) and radio frequency (RF) reactive magnetron sputtering. The structural, optical, and electrical properties of AZO films as-deposited and submitted to annealing treatment (at 300 and 400 ℃, respectively) were characterized using various techniques. The experimental results show that the properties of AZO thin films can be further improved by annealing treatment. The crystallinity of ZnO films improves after annealing treatment. The transmittances of the AZO thin films prepared by DC and RF reactive magnetron sputtering are up to 80% and 85% in the visible region, respectively. The electrical resistivity of AZO thin films prepared by DC reactive magnetron sputtering can be as low as tering have better structural and optical properties than that prepared by DC reactive magnetron sputtering.

  7. Amorphous-nanocrystalline Al doped ZnO transparent conducting thin films

    Energy Technology Data Exchange (ETDEWEB)

    Diez-Betriu, X., E-mail: xdiezbetriu@icmm.csic.es [Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Cientificas, Cantoblanco 28049 Madrid (Spain); Jimenez-Rioboo, R.; Marcos, J. Sanchez-; Cespedes, E.; Espinosa, A.; Andres, A. de [Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Cientificas, Cantoblanco 28049 Madrid (Spain)

    2012-09-25

    Highlights: Black-Right-Pointing-Pointer Al- doped ZnO films by RF- sputtering as amorphous TCO. Black-Right-Pointing-Pointer Structural characterization confirms amorphous-nanocrystalline nature of samples. Black-Right-Pointing-Pointer Optical gap dependence on substrate and grain size. Black-Right-Pointing-Pointer Resistivity correlates to the optical bandgap. - Abstract: Al-doped ZnO films have been deposited at room temperature by means of RF sputtering under different conditions and subjected to annealing treatments looking for amorphous Transparent Conducting Oxide (TCO) films in the search for their integration into the emerging area of the flexible electronics. Structural studies have been performed as well as optical and electrical characterization. Spectroscopic ellipsometry has been used for the determination of the optical gap for films grown on Si and the films thickness. The amorphous fraction of the films (up to 86%) depends on the substrate and RF power but not on the annealing temperature up to 600 Degree-Sign C for glass substrates. The resistivity is found to be independent of the amorphous degree and correlates to the optical bandgap which presents three regimes depending on the annealing temperature.

  8. Structures and properties of the Al-doped ZnO thin films prepared by radio frequency magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Yue Hongyun [School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024 (China); Wu Aimin, E-mail: aimin@dlut.edu.cn [School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024 (China); Key Laboratory of Materials Modification by Laser, Ion and Electron Beams (Dalian University of Technology), Ministry of Education, Dalian 116024 (China); Feng Yudong [State Key Laboratory of Surface Engineering, Lanzhou Institute of Physics, Lanzhou 730000 (China); Zhang Xueyu; Li Tingju [School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024 (China)

    2011-06-01

    Al-doped ZnO thin films were deposited by radio frequency magnetron sputtering using a ZnO target with 2 wt.% Al{sub 2}O{sub 3}. The structures and properties of the films were characterized by the thin film X-ray diffraction, high resolution transmission electron microscopy, Hall system and ultraviolet/visible/near-infrared spectrophotometer. The Al-doped ZnO film with high crystalline quality and good properties was obtained at the sputtering power of 100 W, working pressure of 0.3 Pa and substrate temperature of 250 deg. C. The results of further structure analysis show that the interplanar spacings d are enlarged in other directions besides the direction perpendicular to the substrate. Apart from the film stress, the doping concentration and the doping site of Al play an important role in the variation of lattice parameters. When the doping concentration of Al is more than 1.5 wt.%, part of Al atoms are incorporated in the interstitial site, which leads to the increase of lattice parameters. This viewpoint is also proved by the first principle calculations.

  9. Influence of deposition temperature on structural, optical and electrical properties of sputtered Al doped ZnO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Mosbah, A., E-mail: mosbah_ammar@yahoo.ca [Laboratoire des Couches Minces et Interfaces, Faculte des Sciences, Universite Mentouri 25000 Constantine (Algeria); Departement de Physique, Faculte des Sciences, Universite Ferhat Abbas, 19000 Setif (Algeria); Aida, M.S. [Laboratoire des Couches Minces et Interfaces, Faculte des Sciences, Universite Mentouri 25000 Constantine (Algeria)

    2012-02-25

    Highlights: Black-Right-Pointing-Pointer Al doped ZnO as transparent conducting oxide. Black-Right-Pointing-Pointer Al doping enhances physical properties of ZnO films. Black-Right-Pointing-Pointer Substrate temperature influences structure, morphology and physical properties of ZnO:Al films. Black-Right-Pointing-Pointer The RMS surface roughness decreases with substrate temperature. Black-Right-Pointing-Pointer Both carrier mobility and carrier concentration increase with substrate temperature. - Abstract: Al doped ZnO thin films have been deposited by DC magnetron sputtering technique from ZnO-2 wt.% Al{sub 2}O{sub 3} target onto glass and oxidized silicon substrates heated at temperature ranging between 150 and 370 Degree-Sign C in Ar plasma. X-ray diffraction analysis shows that the deposits have a preferential growth along the c-axis of the hexagonal structure. The average grain size increases from 10 to 59 nm with temperatures ranging from 150 up to 330 Degree-Sign C then it decreases to 45 nm at 370 Degree-Sign C. The root main square (RMS) surface roughness decreases with substrate temperature from 20.9 to 4.1 nm. The films are transparent up to 90% in the visible wavelength range and the optical gap increases with substrate temperature from 3.41 to 3.64 eV. The resistivity measured in Van der Pauw configuration at room temperature is very sensitive to the substrate temperature. It decreases from 5 Multiplication-Sign 10{sup -4} to 3 Multiplication-Sign 10{sup -5} {Omega} cm when the deposition temperature increases from 150 to 370 Degree-Sign C. Both carrier mobility and carrier concentration were found to increase with substrate temperature.

  10. Al-doped ZnO Nanostructured Thin Films: Density Functional Theory and Experiment

    Science.gov (United States)

    Sarma, J. V. N.; Rahman, A.; Jayaganthan, R.; Chowdhury, Rajib; Haranath, D.

    2015-06-01

    Nanostructured Al-doped ZnO (AZO) films are deposited on glass substrates by electroless deposition technique in the present work. AZO films with Al concentration from 1 at.% to 5 at.% are investigated for their structural and morphological properties by X-ray diffraction (XRD), and atomic force microscopy (AFM). An excellent homogeneity is achieved with average crystallite sizes of below 32 nm and a nearly constant root mean square (RMS) surface roughness between 1 nm and 3 nm, for various Al doping concentrations. These smooth and uniform films are characterized for their optical and photoluminescence (PL) properties. A higher value of average transparency between 79% and 92% in the wavelength range of 300-800 nm is achieved, and the PL intensity is found to be a strong function of doping. Density functional theory (DFT) calculations agree with the measured transmittance values, in addition to their predicted electronic structure. Moreover, time-resolved PL measurements indicate that the luminescence decay time decreases with increased doping concentration.

  11. Effects of a Pretreatment on Al-Doped ZnO Thin Films Grown by Atomic Layer Deposition.

    Science.gov (United States)

    Ko, Byoung-Soo; Lee, Sang-Ju; Kim, Dae-Hwan; Hwang, Dae-Kue

    2015-03-01

    In this study, we investigated the electrical, structural, and optical properties of Al-doped ZnO (AZO) thin films approximately 50 nm thick grown by atomic layer deposition (ALD) on glass substrates at 200 °C. An H2O pretreatment was conducted for all AZO samples. The electrical properties of the AZO thin film were improved after the pretreatment process. The Al doping concentrations were controlled by inserting an Al2O3 cycle after every "n" ZnO cycles while varying n from 99 to 16. As the doping concentration increases, the resistivity decreases and the optical band gap increases. When the Al2O3 cycle ratio is 5%, the electrical resistivity showed the lowest value of 4.66 x 10(-3) Ω cm. A carrier concentration of 1.10 x 10(20) cm(-3), and the optical transmittance exceeding 90% were obtained in the visible and near-infrared region. The thin film was strongly textured along the (100) direction in the X-ray diffraction patterns.

  12. Crystal Structure and Optical Properties of Al-Doped ZnO Large-Area Thin Films Using 1500 mm Dual Cylindrical Cathodes.

    Science.gov (United States)

    Lee, JinJu; Ha, Jong-Yoon; Yim, Haena; Choi, Won-Kook; Choi, Ji-Won

    2015-11-01

    The large-area Al-doped ZnO thin films are successfully deposited at room temperature on polycarbonate substrate using a 1500 mm dual cylindrical cathodes sputtering system. Those thin films have smooth surfaces (RMS: 9.6 nm) and lower thicknesses deviation (Uniformity: 98.6%) despite of high RF power. The optical transmittance properties of 3.13 wt% Al doped ZnO thin films have above 85% in visible region. A dual cylindrical cathodes sputtering system can fabricate transparent electrode on flexible electronic devices at room temperature for mass production of 6th generation solar cell and display industry.

  13. Sputtered Al-doped ZnO transparent conducting thin films suitable for silicon solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Ben Ayadi, Z., E-mail: Zouhaier.BenAyadi@fsg.rnu.tn [Laboratoire de Physique des Matériaux et des Nanomatériaux appliquée à l' Environnement, Université de Gabès, Faculté des Sciences de Gabès, Cité Erriadh Manara Zrig, 6072 Gabès (Tunisia); Mahdhi, H. [Laboratoire de Physique des Matériaux et des Nanomatériaux appliquée à l' Environnement, Université de Gabès, Faculté des Sciences de Gabès, Cité Erriadh Manara Zrig, 6072 Gabès (Tunisia); Djessas, K. [Laboratoire Procédés, Matériaux et Energie Solaire (PROMES-CNRS), TECNOSUD, Rambla de la Thermodynamique, 66100 Perpignan (France); Université de Perpignan Via Domitia, 52 Avenue Paul Alduy, 68860, Perpignan Cedex9 (France); Gauffier, J.L. [Département de Génie Physique, INSA de Toulouse, 135 Avenue de Rangueil, 31077 Toulouse cedex 4 (France); and others

    2014-02-28

    Highly transparent conducting Al-doped zinc oxide (AZO) thin films have been grown onto p-type porous silicon substrates by RF-magnetron sputtering at room temperature using aluminum doped nanocrystalline powder. The obtained AZO films were polycrystalline with a hexagonal wurtzite structure and preferentially oriented in the (002) crystallographic direction. The films are highly transparent in the visible wavelength region with a transmittance higher than 85% and an electrical resistivity of 1.56 × 10{sup −4} Ω·cm was obtained at room temperature. On the other hand, we have studied the position of the p–n junction involved in the In{sub 2}O{sub 3}:SnO{sub 2}/(n)AZO/Si(p) structure, by electron-beam induced current technique. Current density–voltage characterizations in dark and under illumination were also investigated. The cell exhibits an efficiency of 5%. - Highlights: • Al-doped zinc oxide (AZO) thin films were grown by RF-magnetron sputtering. • AZO nanopowder compacted target was prepared by a sol–gel method. • AZO thin films are polycrystalline and have preferred orientation along c-axis. • We report a photovoltaic effect in Si(p)/porous silicon/AZO heterostructure. • The cell exhibits an efficiency of 5%.

  14. Structural, Morphological, and LPG Sensing Properties of Al-Doped ZnO Thin Film Prepared by SILAR

    Directory of Open Access Journals (Sweden)

    Shampa Mondal

    2013-01-01

    Full Text Available Undoped and aluminum doped zinc oxide (AZO thin films were deposited on glass substrates by successive ion layer adsorption and reaction (SILAR technique from ammonium zincate complex. The thin films are characterized by X-ray diffraction (XRD and scanning electron microscopy (SEM for their structural and morphological studies. Both undoped and Al-doped film show strong preferred c-axis orientation. The texture coefficient (TC of the film along (002 direction increases due to Al incorporation. SEM micrograph shows round shaped particles for pure ZnO. However AZO films show particles with off spherical shape and compact interconnected grains. Sensitivity of the film in presence of 80% LEL (lower explosive limit of LPG increases with temperature and is maximum at 325°C. Significantly high sensitivity of 87% with reasonably fast response was observed for 1% Al-doped ZnO (AZO film in presence of 1.6 vol% LPG at 325°C.

  15. Chemical and electronic interface structure of spray pyrolysis deposited undoped and Al-doped ZnO thin films on a commercial Cz-Si solar cell substrate

    Energy Technology Data Exchange (ETDEWEB)

    Gabas, M.; Ramos-Barrado, J.R. [Dpto. de Fisica Aplicada I, Lab. de Materiales y Superficies, Universidad de Malaga 29071 Malaga (Spain); Barrett, N.T. [CEA DSM/IRAMIS/SPCSI, CEA Saclay, 91191 Gif sur Yvette (France); Gota, S. [Laboratoire Leon Brillouin, UMR 012 CEA-CNRS CEA Saclay, 91191 Gif sur Yvette (France); Rojas, T.C. [Instituto de Ciencia de Materiales de Sevilla, CSIC, Americo Vespucio 49, 41092 Sevilla (Spain); Lopez-Escalante, M.C. [Isofoton S.A., Parque Tecnologico de Andalucia, Severo Ochoa, 50, 29590 Malaga (Spain)

    2009-08-15

    We have studied differences in the interface between undoped and Al-doped ZnO thin films deposited on commercial Si solar cell substrates. The undoped ZnO film is significantly thicker than the Al-doped film for the same deposition time. An extended silicate-like interface is present in both samples. Transmission electron microscopy (TEM) and photoelectron spectroscopy (PES) probe the presence of a zinc silicate and several Si oxides in both cases. Although Al doping improves the conductivity of ZnO, we present evidence for Al segregation at the interface during deposition on the Si substrate and suggest the presence of considerable fixed charge near the oxidized Si interface layer. The induced distortion in the valence band, compared to that of undoped ZnO, could be responsible for considerable reduction in the solar cell performance. (author)

  16. Fabrication of nanostructured Al-doped ZnO thin film for methane sensing applications

    Science.gov (United States)

    Shafura, A. K.; Sin, N. D. Md.; Azhar, N. E. I.; Saurdi, I.; Uzer, M.; Mamat, M. H.; Shuhaimi, A.; Alrokayan, Salman A. H.; Khan, Haseeb A.; Rusop, M.

    2016-07-01

    CH4 gas sensor was fabricated using spin-coating method of the nanostructured ZnO thin film. Effect of annealing temperature on the electrical and structural properties of the film was investigated. Dense nanostructured ZnO film are obtained at higher annealing temperature. The optimal condition of annealing temperature is 500°C which has conductivity and sensitivity value of 3.3 × 10-3 S/cm and 11.5%, respectively.

  17. Effects of Al Doping on the Properties of ZnO Thin Films Deposited by Atomic Layer Deposition.

    Science.gov (United States)

    Zhai, Chen-Hui; Zhang, Rong-Jun; Chen, Xin; Zheng, Yu-Xiang; Wang, Song-You; Liu, Juan; Dai, Ning; Chen, Liang-Yao

    2016-12-01

    The tuning of structural, optical, and electrical properties of Al-doped ZnO films deposited by atomic layer deposition technique is reported in this work. With the increasing Al doping level, the evolution from (002) to (100) diffraction peaks indicates the change in growth mode of ZnO films. Spectroscopic ellipsometry has been applied to study the thickness, optical constants, and band gap of AZO films. Due to the increasing carrier concentration after Al doping, a blue shift of band gap and absorption edge can be observed, which can be interpreted by Burstein-Moss effect. The carrier concentration and resistivity are found to vary significantly among different doping concentration, and the optimum value is also discussed. The modulations and improvements of properties are important for Al-doped ZnO films to apply as transparent conductor in various applications.

  18. Effects of Al Doping on the Properties of ZnO Thin Films Deposited by Atomic Layer Deposition

    Science.gov (United States)

    Zhai, Chen-Hui; Zhang, Rong-Jun; Chen, Xin; Zheng, Yu-Xiang; Wang, Song-You; Liu, Juan; Dai, Ning; Chen, Liang-Yao

    2016-09-01

    The tuning of structural, optical, and electrical properties of Al-doped ZnO films deposited by atomic layer deposition technique is reported in this work. With the increasing Al doping level, the evolution from (002) to (100) diffraction peaks indicates the change in growth mode of ZnO films. Spectroscopic ellipsometry has been applied to study the thickness, optical constants, and band gap of AZO films. Due to the increasing carrier concentration after Al doping, a blue shift of band gap and absorption edge can be observed, which can be interpreted by Burstein-Moss effect. The carrier concentration and resistivity are found to vary significantly among different doping concentration, and the optimum value is also discussed. The modulations and improvements of properties are important for Al-doped ZnO films to apply as transparent conductor in various applications.

  19. Crystalline silicon surface passivation by thermal ALD deposited Al doped ZnO thin films

    Directory of Open Access Journals (Sweden)

    Jagannath Panigrahi

    2017-03-01

    Full Text Available The evidence of good quality silicon surface passivation using thermal ALD deposited Al doped zinc oxide (AZO thin films is demonstrated. AZO films are prepared by introducing aluminium precursor in between zinc and oxygen precursors during the deposition. The formation of AZO is confirmed by ellipsometry, XRD and Hall measurements. Effective minority carrier lifetime (τeff greater than 1.5ms at intermediate bulk injection levels is realized for symmetrically passivated p-type silicon surfaces under optimised annealing conditions of temperature and time in hydrogen ambient. The best results are realised at 450°C annealing for >15min. Such a layer may lead to implied open circuit voltage gain of 80mV.

  20. Environmental stability of solution processed Al-doped ZnO naoparticulate thin films using surface modification technique

    Science.gov (United States)

    Vunnam, Swathi; Ankireddy, Krishnamraju; Kellar, Jon; Cross, William

    2014-12-01

    The environmental stability of solution processed Al-doped ZnO (AZO) thin films was enhanced by functionalizing the film surface with a thin self-assembled molecular layer. Functionalization of AZO films was performed using two types of molecules having identical 12-carbon alkyl chain termination but different functional groups: dodecanethiol (DDT) and dodecanoic acid (DDA). Surface modified AZO films were examined using electrical resistivity measurements, contact angle measurements and quantitative nanomechanical property mapping atomic force microscopy. The hydrophobic layer inhibits the penetration of oxygen and water into the AZO's grain boundaries thus significantly increasing the environmental stability over unmodified AZO. Surface modified AZO films using DDT exhibited lower electrical resistivity compared to DDA functionalized AZO films. Our study demonstrates a new approach for improving the physical properties of oxide based nanoparticulate films for device applications.

  1. ZnO and Al doped ZnO thin films deposited by Spray Plasma: Effect of the growth time and Al doping on microstructural, optical and electrical properties

    Energy Technology Data Exchange (ETDEWEB)

    Baba, Kamal [LSPM-CNRS, Laboratoire des Sciences des Procédés et des Matériaux (UPR 3407), Université Paris 13 Sorbonne Paris Cité, 93430 Villetaneuse (France); Luxembourg Institute of Science and Technology, Materials Research and Technology Department, L-4362 Esch-sur-Alzette (Luxembourg); Lazzaroni, Claudia [LSPM-CNRS, Laboratoire des Sciences des Procédés et des Matériaux (UPR 3407), Université Paris 13 Sorbonne Paris Cité, 93430 Villetaneuse (France); Nikravech, Mehrdad, E-mail: mehrdad.nikravech@lspm.cnrs.fr [LSPM-CNRS, Laboratoire des Sciences des Procédés et des Matériaux (UPR 3407), Université Paris 13 Sorbonne Paris Cité, 93430 Villetaneuse (France)

    2015-11-30

    Nanostructured zinc oxide (ZnO) and Al doped ZnO (ZnO:Al) thin films are deposited on glass substrate by the Spray Plasma technique. Zinc nitrate and aluminium nitrate are used as Zn and Al precursors, respectively. The effect of the growth time on structural and optical properties of undoped films is studied by X-ray diffraction, atomic force microscopy, and UV–Vis spectroscopy. The effect of Al doping on microstructural, optical and electrical characteristics of ZnO:Al films is also investigated. The results show that the grain size and the film thickness both increase with the growth time. The band gap of the layers varies from 3.17 to 3.24 eV depending on the thickness. The increase of the Al doping results in the enlargement of the peak (002) and the shift of its position to higher 2θ values. Average optical transmittance decreases from 90 to 65% with the growth time because of the thickness increase while there is no significant influence of the aluminium doping on the transmittance which is above 80% in most of the visible and near-IR range for all ZnO:Al films. The electrical properties characterized by Hall measurements show that all the deposited films exhibit high resistivity, between 4 and 10{sup 4} Ω cm. The carrier concentration decreases from 2.10{sup 19} to 2.10{sup 13} cm{sup −3} when the concentration of Al increases from 1.5 to 5 atm%. - Highlights: • The original Spray Plasma technique is used for ZnO and ZnO:Al thin film deposition. • Investigation of the effect of growth time and Al doping on the structural and optical properties • Increase of grain size and film thickness with the growth time • Optical transmittance decreases from 90 to 65% with the growth time and is above 80% for ZnO:Al films in UV–Vis-NIR range. • The peak position of the (002) plane is shifted to high 2θ values with Al doping.

  2. Effect of Annealing Conditions on Properties of Sol-Gel Derived Al-Doped ZnO Thin Films

    Institute of Scientific and Technical Information of China (English)

    GAO Mei-Zhen; ZHANG Feng; LIU Jing; SUN Hui-Na

    2009-01-01

    Transparent conductive Al-doped ZnO (AZO) thin films are prepared on normal glass substrates by the sol-gel spin coating method.The effects of drying conditions,annealing temperature and cooling rate on the structural,electrical and optical properties of AZO films are investigated by x-ray diffraction,scanning electron microscopy,the four-point probe method and UV- VIS spectrophotometry,respectively.The deposited films show a hexagonal wurtzite structure and high preferential c-axis orientation.As the drying temperature increases from 100℃ to 300℃ the resistivity of AZO films decreases dramatically.In contrast to the annealed films cooled in a furnace and in air,the resistivity of the annealed film which is cooled at -15℃ is greatly reduced.Increasing the cooling rate dramatically increases the electrical conductivity of AZO films.

  3. Al doped ZnO thin films - microstructure, physical and sensor properties

    Science.gov (United States)

    Starbov, N.; Balabanov, S.; Bineva, I.; Rachkova, A.; Krumov, E.; Starbova, K.

    2012-12-01

    Thin ZnO films doped with Al are deposited by spray pyrolysis onto glass substrates using starting solution of Zn-acetate + n.AlCl (where 0.1 detection of noxious gases is checked via resistivity measurements under saturated vapours of ethanol, acetone, ammonia, dimethylamine and formalin at room temperature. Finally the results obtained are discussed concerning the application of the ZnO:Al films studied in the field of sensor technique.

  4. Effect of low energy ion bombardment on structure and photoluminescence characterization of Al-doped ZnO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Jin, Chenggang; Yu, Tao; Wu, Zaofeng; Wu, Xuemei [Department of Physics, Soochow University, Soochow 215006 (China); Zhuge, Lanjian, E-mail: ljzhuge@suda.edu.cn [Analysis and Testing Center, Soochow University, Soochow 215006 (China)

    2012-12-01

    Al-doped zinc oxide (AZO) films are prepared by dual ion-beam assisted sputter deposition at room temperature. An assisting argon ion beam (ion energy E{sub i} = 0-300 eV) directly bombards the substrate surface to modify the properties of the AZO films. The effects of assisting ion beam energy on the characteristics of AZO films were investigated based on transmission electron microscopy, atomic force microscopy, X-ray photoelectron spectroscopy and photoluminescence measurement. With increasing assisting ion beam bombardment, the crystalline quality of the AZO films was improved and the oxygen vacancies were increased observably. Two red emissions originating from the oxygen vacancies in the films appear at 1.71 and 1.64 eV. This study suggests that wide-band-gap materials could act as effective visible light emitters and ion beam bombardment provides a simple route to synthesize such materials. - Highlights: Black-Right-Pointing-Pointer Al-doped ZnO (AZO) thin films were prepared by dual ion-beam sputter deposition. Black-Right-Pointing-Pointer By assisting-ion beam bombardment, AZO films have a better c-axis orientation. Black-Right-Pointing-Pointer The crystalline quality of AZO films was improved by assisting-ion beam bombardment. Black-Right-Pointing-Pointer Two red emissions originate from the oxygen vacancies in the films.

  5. Optical and electrical characteristics of Al-doped ZnO thin films prepared by aqueous phase deposition

    Energy Technology Data Exchange (ETDEWEB)

    Yao, Pin-Chuan, E-mail: pcyao@mail.dyu.edu.tw [Department of Materials Science and Engineering, Da-Yeh University, 168 University Rd., Dacun, Changhua 51591, Taiwan (China); Hang, Shih-Tse; Lin, Yu-Shuan [Department of Materials Science and Engineering, Da-Yeh University, 168 University Rd., Dacun, Changhua 51591, Taiwan (China); Yen, Wen-Tsai; Lin, Yi-Cheng [Department of Mechatronics Engineering, National Changhua University of Education, Changhua 50007, Taiwan (China)

    2010-12-15

    Transparent conducting Al-doped ZnO (AZO) thin films have been deposited by sol-gel route. Starting from an aqueous solution of zinc acetate by adding aluminum chloride as dopant, a c-axis oriented polycrystalline ZnO thin film 100 nm in thickness could be spin-coated on glass substrates via a two-step annealing process under reducing atmosphere. The effects of thermal annealing and dopant concentration on the structural, electrical and optical properties of AZO thin films were investigated. The post-treated AZO films exhibited a homogenous dense microstructure with grain sizes less than 10 nm as characterized by SEM photographs. The annealing atmosphere has prominent impact on the crystallinity of the films which will in turn influence the electrical conductivity. By varying the doping concentrations, the optical and electrical properties could be further adjusted. An optimal doping concentration of Al/Zn = 2.25 at.% was obtained with minimum resistivity of 9.90 x 10{sup -3} {Omega}-cm whereas the carrier concentration and mobility was 1.25 x 10{sup 20} cm{sup -3} and 5.04 cm{sup 2} V{sup -1} s{sup -1}, respectively. In this case, the optical transmittance in the visible region is over 90%.

  6. Improving the uncommon (110) growing orientation of Al-doped ZnO thin films through sequential pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Coman, Tudor [Faculty of Physics, “Al. I. Cuza” University, 11 Carol I Blvd., Iasi 700506 (Romania); Ursu, Elena Laura [Centre of Advanced Research in Bionanoconjugates and Biopolymers, “Petru Poni” Institute of Macromolecular Chemistry, 41 A Grigore Ghica Voda Alley, Iasi 700487 (Romania); Nica, Valentin; Tiron, Vasile [Faculty of Physics, “Al. I. Cuza” University, 11 Carol I Blvd., Iasi 700506 (Romania); Olaru, Mihaela; Cotofana, Corneliu [Polymer Materials Physics Laboratory, “Petru Poni” Institute of Macromolecular Chemistry, 41 A Gr. Ghica Voda Alley, Iasi 700487 (Romania); Dobromir, Marius [Faculty of Physics, “Al. I. Cuza” University, 11 Carol I Blvd., Iasi 700506 (Romania); Coroaba, Adina [Centre of Advanced Research in Bionanoconjugates and Biopolymers, “Petru Poni” Institute of Macromolecular Chemistry, 41 A Grigore Ghica Voda Alley, Iasi 700487 (Romania); Dragos, Oana-Georgiana; Lupu, Nicoleta [National Institute of Research and Development for Technical Physics, 47 Mangeron Blvd., Iasi 700050 (Romania); Caltun, Ovidiu Florin [Faculty of Physics, “Al. I. Cuza” University, 11 Carol I Blvd., Iasi 700506 (Romania); Ursu, Cristian, E-mail: cristian.ursu@icmpp.ro [Polymer Materials Physics Laboratory, “Petru Poni” Institute of Macromolecular Chemistry, 41 A Gr. Ghica Voda Alley, Iasi 700487 (Romania)

    2014-11-28

    High quality Al-doped ZnO (AZO) films with uncommon (110) orientation are obtained on amorphous substrate by using Sequential Pulsed Laser Deposition technique. The dependence of the structural, optical and electrical properties with dopant concentration and oxygen deposition pressure was investigated systematically. We note a transition from the (002) preferential orientation of crystallites to an uncommon (110) orientation due to a combined effect of doping concentration and deposition pressure decreasing. For constant deposition pressure of 5 Pa the film crystallinity is changed from preferential (002) to polycrystalline when increasing dopant concentration. For the maximum dopant concentration that we have investigated (i.e., 4.4% at.) structural properties of AZO films are changed from a polycrystalline phase to a (110) preferential orientation when the deposition pressure decreases. This uncommon growth mode is accompanied by a change of the morphology from a densely packed granular structure to a more rarefied one. Moreover, the band gap widens up to 3.88 eV and the electrical resistivity drops to 5.4 × 10{sup −2} Ω cm. The structural changes were attributed to two mechanisms: a first one, responsible for the (002) phase suppression as a consequence of aluminum ion bombardment during the doping process and, a second one, in charge with (110) phase growth as the diffusion rates of zinc and oxygen atoms are affected by the dopant incorporation and by the decrease of deposition pressure. - Highlights: • Sequential PLD (SPLD) of (110) Al-doped ZnO thin films on amorphous substrate • Highly c-axis oriented films with high transparency and low resistivity • Fine tuning of the dopant concentration through SPLD method.

  7. Highly transparent and conductive Al-doped ZnO nanoparticulate thin films using direct write processing.

    Science.gov (United States)

    Vunnam, S; Ankireddy, K; Kellar, J; Cross, W

    2014-05-16

    Solution processable Al-doped ZnO (AZO) thin films are attractive candidates for low cost transparent electrodes. We demonstrate here an optimized nanoparticulate ink for the fabrication of AZO thin films using scalable, low-cost direct write processing (ultrasonic spray deposition) in air at atmospheric pressure. The thin films were made via thermal processing of as-deposited films. AZO films deposited using the proposed nanoparticulate ink with further reducing in vacuum and rf plasma of forming gas exhibited optical transparency greater than 95% across the visible spectrum, and electrical resistivity of 0.5 Ω cm and it drops down to 7.0 × 10(-2) Ω cm after illuminating with UV light, which is comparable to commercially available tin doped indium oxide colloidal coatings. Various structural analyses were performed to investigate the influence of ink chemistry, deposition parameters, and annealing temperatures on the structural, optical, and electrical characteristics of the spray deposited AZO thin films. Optical micrographs confirmed the presence of surface defects and cracks using the AZO NPs ink without any additives. After adding N-(2-Aminoethyl)-3-aminopropylmethyldimethoxy silane to the ink, AZO films exhibited an optical transparency which was virtually identical to that of the plain glass substrate.

  8. Near infrared ray annealing effects on the properties of Al-doped ZnO thin films prepared by spin-coating method.

    Science.gov (United States)

    Jun, Min-Chul; Park, Sang-Uk; Chae, Moon-Soon; Shin, Dong-Jin; Ha, Jae-Geun; Koo, Sang-Mo; Lee, Kyung-Ju; Moon, Byung-Moo; Song, Chi-Young; Koh, Jung-Hyuk

    2013-09-01

    In this research, we will present Al doped ZnO thin films for transparent conducting oxide applications. Aluminum doped zinc oxide (AZO) thin films have been deposited on the glass substrates by sol-gel spin-coating method using zinc acetate dehydrate (Zn(CH3COO)2 2H2O) and aluminum chloride hexahydrate (AlCl3 x 6H2O) as cation sources. In this study, we investigated the effects of near infrared ray (NIR) annealing on the structural, optical and electrical characteristics of the AZO thin films. The experimental results showed that AZO thin films have a hexagonal wurtzite crystal structure and had a good transmittance higher than 85% within the visible wavelength region. It was also found that the additional energy of NIR helps to improve the electrical properties of Al doped ZnO transparent conducting oxides.

  9. Effect of Al Doping on Structural, Electrical, Optical and Photoluminescence Properties of Nano-Structural ZnO Thin Films

    Institute of Scientific and Technical Information of China (English)

    M. Mozibur Rahman; M.K.R. Khan; M. Rafiqul Islam; M.A. Halim; M. Shahjahan; M.A. Hakim; Dilip Kumar Saha; Jasim Uddin Khan

    2012-01-01

    The nano-structural Al-doped ZnO thin films of different morphologies deposited on glass substrate were successfully fabricated at substrate temperature of 350 ℃ by an inexpensive spray pyrolysis method. The structural, electrical, optical and photoluminescence properties were investigated. X-ray diffraction study revealed the crystalline wurtzite (hexagonal) structure of the films with nano-grains. Scanning electron microscopy (SEM) micrographs indicated the formation of a large variety of nano-structures during film growth. The spectral absorption of the films occurred at the absorption edge of -410 nm. In the present study, the optical band gap energy 3.28 eV of ZnO decreased gradually to 3.05 eV for 4 mol% of AI doping. The deep level activation energy decreased and carrier concentrations increased substantially with increasing doping. Exciting with the energy 3.543 eV (A=350 nm), a narrow and a broad characteristic photoluminescence peaks that correspond to the near band edge (NBE) and deep level emissions (DLE), respectively emerged.

  10. Transparent conductive Al-doped ZnO thin films grown at room temperature

    Energy Technology Data Exchange (ETDEWEB)

    Wang Yuping; Lu Jianguo; Bie Xun; Gong Li; Li Xiang; Song Da; Zhao Xuyang; Ye Wenyi; Ye Zhizhen [State Key Laboratory of Silicon Materials, Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027 (China)

    2011-05-15

    Aluminum-doped ZnO (ZnO:Al, AZO) thin films were prepared on glass substrates by dc reactive magnetron sputtering from a Zn-Al alloy target at room temperature. The effects of the Ar-to-O{sub 2} partial pressure ratios on the structural, electrical, and optical properties of AZO films were studied in detail. AZO films grown using 100:4 to 100:8 Ar-to-O{sub 2} ratio result in acceptable quality films with c-axis orientated crystals, uniform grains, 10{sup -3} {Omega} cm resistivity, greater than 10{sup 20} cm{sup -3} electron concentration, and high transmittance, 90%, in the visible region. The lowest resistivity of 4.11x10{sup -3} {Omega} cm was obtained under the Ar-to-O{sub 2} partial pressure ratio of 100:4. A relatively strong UV emission at {approx}3.26 eV was observed in the room-temperature photoluminescence spectrum. X-ray photoelectron spectroscopy analysis confirmed that Al was introduced into ZnO and substitutes for Zn and doped the film n-type.

  11. Environmental stability of solution processed Al-doped ZnO naoparticulate thin films using surface modification technique

    Energy Technology Data Exchange (ETDEWEB)

    Vunnam, Swathi, E-mail: swathivunnam@gmail.com [Program of Nanoscience and Nanoengineering, South Dakota School of Mines and Technology, Rapid City, SD 57701 (United States); Ankireddy, Krishnamraju; Kellar, Jon [Program of Materials Engineering and Science, South Dakota School of Mines and Technology, Rapid City, SD 57701 (United States); Cross, William, E-mail: William.Cross@sdsmt.edu [Program of Materials Engineering and Science, South Dakota School of Mines and Technology, Rapid City, SD 57701 (United States)

    2014-12-15

    Graphical abstract: - Highlights: • AZO nanoparticulate films were deposited using ultrasonic spray deposition. • Functionalization of solution processed AZO thin films was carried out. • Contact angles and QNM AFM results confirmed the existence of molecular layers. • Environmental stability of AZO films greatly increased with surface modification. - Abstract: The environmental stability of solution processed Al-doped ZnO (AZO) thin films was enhanced by functionalizing the film surface with a thin self-assembled molecular layer. Functionalization of AZO films was performed using two types of molecules having identical 12-carbon alkyl chain termination but different functional groups: dodecanethiol (DDT) and dodecanoic acid (DDA). Surface modified AZO films were examined using electrical resistivity measurements, contact angle measurements and quantitative nanomechanical property mapping atomic force microscopy. The hydrophobic layer inhibits the penetration of oxygen and water into the AZO's grain boundaries thus significantly increasing the environmental stability over unmodified AZO. Surface modified AZO films using DDT exhibited lower electrical resistivity compared to DDA functionalized AZO films. Our study demonstrates a new approach for improving the physical properties of oxide based nanoparticulate films for device applications.

  12. Effects of Al concentration on microstructural characteristics and electrical properties of Al-doped ZnO thin films on Si substrates by atomic layer deposition.

    Science.gov (United States)

    Lee, Ju Ho; Lee, Jae-Won; Hwang, Sooyeon; Kim, Sang Yun; Cho, Hyung Koun; Lee, Jeong Yong; Park, Jin-Seong

    2012-07-01

    Al-doped ZnO (AZO) thin films with various Al concentrations were synthesized on Si(001) substrates with native oxide layers by atomic layer deposition process. The effects of the Al concentration on the microstructural characteristics of the AZO thin films grown at 250 degrees C and the correlation between their microstructural characteristics and electrical properties of the AZO thin films were investigated by AFM, XRD, HRTEM and Hall measurements. The XRD and HRTEM results revealed that the crystallinity and electrical properties of the undoped ZnO thin films were enhanced by 2.48 at% Al doping. However, 12.62 at% Al doping induced the deterioration of their crystallinity and electrical properties due to the formation of nano-sized metallic Al clusters and randomly oriented ZnO-based nano-crystals. To enhance the electrical properties of the AZO thin films while maintaining their crystallinity and electrical properties, a moderate Al concentration has to be chosen under the solubility limit of Al in ZnO.

  13. Influence of growth temperature on the electrical and structural characteristics of conductive Al-doped ZnO thin films grown by atomic layer deposition

    Energy Technology Data Exchange (ETDEWEB)

    Ahn, Cheol Hyoun [School of Advanced Materials Science and Engineering, Sungkyunkwan University, 2066 Seobu-ro, Jangan-gu, Suwon, Gyeonggi-do (Korea, Republic of); Lee, Sang Yeol, E-mail: sylee@cju.ac.kr [Department of Semiconductor Engineering, Cheongju University, Cheongju, Chungbuk, 360-764 (Korea, Republic of); Cho, Hyung Koun, E-mail: chohk@skku.edu [School of Advanced Materials Science and Engineering, Sungkyunkwan University, 2066 Seobu-ro, Jangan-gu, Suwon, Gyeonggi-do (Korea, Republic of)

    2013-10-31

    Al-doped ZnO thin films (AZO) were deposited by atomic layer deposition at various temperatures (100–300 °C) with a frequency ratio of 19/1 (Zn–O/Al–O), and their properties were evaluated. With increasing growth temperature, the Al contents in the AZO thin films were continuously increased, because of the rapid increase in the incorporation efficiency of the Al–O layer with respect to the Zn–O layer. Although low-temperature deposition resulted in the abnormal [100]-preferred orientation of the AZO films, they had a high carrier density of ∼ 10{sup 20} cm{sup 3}. However, the Hall mobility showed a low value of 1.5 cm{sup 2}/Vs due to the high density of impurities such as C–O or O–H caused by incomplete reaction for precursors. In contrast, the electrical and structural properties of the AZO thin films were enhanced by increasing growth temperature, due to the increased Al doping level and reduced residual impurities, which was confirmed by X-ray diffraction and X-ray photoelectron spectroscopy. - Highlights: • Dependency of growth temperature on characterization of Al-doped ZnO • The preferred orientation was attributed to the chemical reactions of precursors • The residual impurities were reduced with increased growth temperature • The Al doping efficiency was enhanced with increasing growth temperature • Conductivity was enhanced with higher doping efficiency in high growth temperature.

  14. Effect of aging under ambient conditions on the optical properties of Al-doped ZnO thin films deposited by direct current sputtering

    Science.gov (United States)

    Barhoumi, A.; Leroy, G.; Duponchel, B.; Gest, J.; Guermazi, S.

    2017-01-01

    Transparent and conductive Al-doped ZnO (AZO) thin films were deposited on a glass substrate by direct current sputtering. In a previous study, we noted the influence of time on structural and electrical characteristics of films. In the present paper, the effect of a two-year aging under ambient conditions on the optical properties was investigated. A global improvement of the optical properties of AZO thin films was observed. The optical transmittance spectra revealed a high transmittance more than 90% in the Vis-NIR regions and a high absorption in the ultraviolet range. It is assumed that the crystallinity segregation leads to the decrease of optical scattering. The results from the optical measurements showed a reorganization of the structure leading to the degradation of the structural homogeneity. Nevertheless, the evolution of the figure of merit shows that Al-doped ZnO is a good candidate for the manufacturing and the commercialization of transparent conducting oxide devices.

  15. Influence of electron beam irradiation on nonlinear optical properties of Al doped ZnO thin films for optoelectronic device applications in the cw laser regime

    Science.gov (United States)

    Antony, Albin; Pramodini, S.; Poornesh, P.; Kityk, I. V.; Fedorchuk, A. O.; Sanjeev, Ganesh

    2016-12-01

    We present the studies on third-order nonlinear optical properties of Al doped ZnO thin films irradiated with electron beam at different dose rate. Al doped ZnO thin films were deposited on a glass substrate by spray pyrolysis deposition technique. The thin films were irradiated using the 8 MeV electron beam from microtron ranging from 1 kG y to 5 kG y. Nonlinear optical studies were carried out by employing the single beam Z-scan technique to determine the sign and magnitude of absorptive and refractive nonlinearities of the irradiated thin films. Continuous wave He-Ne laser operating at 633 nm was used as source of excitation. The open aperture Z-scan measurements indicated the sample displays reverse saturable absorption (RSA) process. The negative sign of the nonlinear refractive index n2 was noted from the closed aperture Z-scan measurements indicates, the films exhibit self-defocusing property due to thermal nonlinearity. The third-order nonlinear optical susceptibility χ(3) varies from 8.17 × 10-5 esu to 1.39 × 10-3 esu with increase in electron beam irradiation. The present study reveals that the irradiation of electron beam leads to significant changes in the third-order optical nonlinearity. Al doped ZnO displays good optical power handling capability with optical clamping of about ∼5 mW. The irradiation study endorses that the Al doped ZnO under investigation is a promising candidate photonic device applications such as all-optical power limiting.

  16. Absorption Measurement of Zn Atom Density during ICP-assisted Magnetron Sputter-deposition of Al-doped ZnO Thin Films

    OpenAIRE

    2009-01-01

    This paper reports the outlines of hollow cathode (HCD) lamp absorption system for the density measurement of sputtered metal atoms in the inductively coupled plasma (ICP) assisted sputter-deposition process of Al doped ZnO thin films. As a result, absorbance of about 6.5% was obtained, which corresponds to the Zn atom density of 1.5×1012 cm-3.

  17. Fabrication of high infrared reflective Al-doped ZnO thin films through electropulsing treatment for solar control

    Energy Technology Data Exchange (ETDEWEB)

    Miao, Dagang, E-mail: chinesemdg@163.com; Hu, Huawen; Gan, Lu

    2015-08-05

    Highlights: • Rapid electropulsing treatment (EPT) was applied on AZO thin films. • AZO film presented electrical resistivity of 9.03 × 10{sup −4} Ω cm after 4.5 min of EPT. • AZO film presented high infrared reflection rate of 80–85% after 4.5 min of EPT. • The prepared AZO film can be used as solar control film. - Abstract: In this study, Al-doped ZnO (AZO) thin films were finished by low-energy consumed electropulsing treatment (EPT) in a short time. The EPT effect on the resulting AZO films was investigated by X-ray Diffraction (XRD), Hall Effect measurement, UV–visible transmittance spectra, Scanning Electron Microscope (SEM), Atomic Force Microscopy (AFM) and Fourier Transform Infrared Spectroscopy. As compared with the other EPT-treated AZO films, the prepared AZO films corresponding to 4.5 min EPT exhibited higher degree of crystallization, higher visible transmittance with blue shift, smoother surface, lower electrical resistivity of 9.03 × 10{sup −4} Ω cm, and higher infrared reflection rate of 80–85%. By the 4.5 min of EPT, the electrical conductivity of the resulting AZO thin film was increased by approximately 82.3%. Moreover, it was also found that prolonged EPT would degrade the film properties. These results indicate that the fast and low-energy consumed EPT might be a promising substitution for traditional heat annealing, and the prepared high infrared reflective AZO films make them promising candidates for being applied as solar control films.

  18. Structural, Morphological, and LPG Sensing Properties of Al-Doped ZnO Thin Film Prepared by SILAR

    OpenAIRE

    Shampa Mondal; Shatabda Bhattacharya; Mitra, P.

    2013-01-01

    Undoped and aluminum doped zinc oxide (AZO) thin films were deposited on glass substrates by successive ion layer adsorption and reaction (SILAR) technique from ammonium zincate complex. The thin films are characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) for their structural and morphological studies. Both undoped and Al-doped film show strong preferred c-axis orientation. The texture coefficient (TC) of the film along (002) direction increases due to Al incorpo...

  19. Effect of laser irradiation on gas sensing properties of sol–gel derived nanocrystalline Al-doped ZnO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Hou, Yue; Jayatissa, Ahalapitiya H., E-mail: ajayati@utnet.utoledo.edu

    2014-07-01

    The effect of laser irradiation on the performance of gas sensor made with sol–gel derived Al-doped ZnO thin films was investigated. The films with desired thicknesses were deposited on the alkali-free glass substrates by a sol–gel process. A pulsed laser system with a wavelength of 532 nm, a pulsed duration of 8 ns, pulsed frequency of 5 kHz and the laser fluence in the range of 1.06–3.58 J/cm{sup 2} was used as the irradiation source. The microstructure, optical transmittance, surface morphology, electrical conductivity and gas sensor performance of the as-deposited and laser-irradiated Al-doped ZnO films were studied as a function of laser energy level. The X-ray diffraction results indicated that low laser energy significantly enhanced the crystallinity and promoted grain growth, whereas high laser energy irradiation resulted in deterioration of crystalline quality. It was also found that the laser irradiation affected the surface morphology and electrical conductivity of ZnO films. The gas sensor performance of Al-doped ZnO sensors was examined in terms of ZnO film thicknesses and H{sub 2} concentrations in the air at an operating temperature of 130 °C. It was found that the sensing response of Al-doped ZnO sensors varied depending on the film thickness as well as the laser energy level. An optimum laser energy level resulted in high and rapid response characteristics of gas sensors for the detection of H{sub 2}. The results also suggested that the crystallinity was critical to achieve the optimum sensor performance. - Highlights: • Aluminum was doped in ZnO thin films via a sol–gel coating process. • Laser irradiation was employed to improve the effect of doping. • The properties of ZnO were investigated as a function of laser energy. • We found that the laser irradiation enhances the gas sensor performance.

  20. High-energy electron beam irradiation of Al-doped ZnO thin films deposited at room temperature

    Energy Technology Data Exchange (ETDEWEB)

    Yun, Eui-Jung; Jung, Jin-Woo [Hoseo University, Asan (Korea, Republic of); Hwang, Jong-Ha; Lee, Byung-Cheol [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Jung, Myung-Hee [Anyang University, Anyang (Korea, Republic of)

    2011-03-15

    In this research, we demonstrated the effects of high-energy electron beam irradiation (HEEBI) on the optical and structural properties of Al-doped ZnO (AZO) films grown on transparent corning glass substrates at room temperature (RT) by using a radio-frequency magnetron sputtering technique. The AZO thin films were treated with HEEBI in air at RT at an electron beam energy of 0.8 MeV and doses of 1 x 10{sup 14} - 1 x 10{sup 16} electrons/cm{sup 2}. The photoluminescence (PL) measurements revealed that the dominant peak at 2.77 eV was a blue emission originating from donor-like defects, oxygen vacancies (V{sub o}), suggesting that the n-type conductivity was preserved in HEEBI-treated films. On the basis of PL, X-ray diffraction (XRD), and X-ray photoelectron spectroscopy results, we suggest that the density of V{sub o} donor defects is decreased due to in-diffusion of oxygen from the ambient into the films after HEEBI treatment at low doses up to 10{sup 15} electrons/cm{sup 2} while the opposite phenomenon can occur with further increase in the dose. We also found from the XRD analysis that the worse crystallinity with a smaller grain size was observed in HEEBI-treated AZO films at a higher dose, corresponding to a higher oxygen fraction in the films. We believe that our results will contribute to developing high-quality AZO-based materials and devices for space applications.

  1. Structural Properties of Ultrasonically Sprayed Al-Doped ZnO (AZO) Thin Films: Effect of ZnO Buffer Layer on AZO

    Science.gov (United States)

    Babu, B. J.; Velumani, S.; Arenas-Alatorre, J.; Kassiba, A.; Chavez, Jose; Park, Hyeonsik; Hussain, Shahzada Qamar; Yi, Junsin; Asomoza, R.

    2015-02-01

    Transparent aluminium-doped ZnO (AZO)-conducting oxide films were deposited on a glass substrate, using an ultrasonic spray pyrolysis (USP) system at 475°C. We investigated the effects of the Al/Zn atomic ratios on the structural properties of the AZO films. All the deposited AZO thin films presented hexagonal wurtzite structure. As Al doping increased in the film, the preferential orientation switched from [002] to [101], and crystallite sizes varied from 31.90 nm to 34.5 nm. Field emission scanning electron microscopy showed a change in the surface morphology of the AZO films with respect to the Al/Zn ratio, and secondary ion mass spectroscopy showed that the amount of Al incorporated into the films was proportional to the concentration of the starting solution. A fast Fourier transform of the AZO film measurements confirmed the presence of (100), (102), and (200) reflections, corresponding to a wurtzite structure of the AZO thin films. The plane corresponding to AZO was simulated, and matched the experimental pattern obtained from high-resolution transmission electron microscopy. An un-doped ZnO layer was deposited onto the AZO film using USP at 400°C, and a bilayer of AZO/ZnO was annealed in vacuum for 20 min at 350°C. The resistivity of these bilayer films was lower than that of a single-layered AZO film, and it further decreased by vacuum annealing.

  2. Effects of Al Concentration on Structural and Optical Properties of Al-doped ZnO Thin Films

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Min Su; Yim, Kwang Gug; Leem, Jae Young [Inje University, Gimhae (Korea, Republic of); Son, Jeong Sik [Kyungwoon University, Gumi (Korea, Republic of)

    2012-04-15

    Aluminium (Al)-doped zinc oxide (AZO) thin films with different Al concentrations were prepared by the solgel spin-coating method. Optical parameters such as the optical band gap, absorption coefficient, refractive index, dispersion parameter, and optical conductivity were studied in order to investigate the effects of the Al concentration on the optical properties of AZO thin films. The dispersion energy, single-oscillator energy, average oscillator wavelength, average oscillator strength, and refractive index at infinite wavelength of the AZO thin films were found to be affected by Al incorporation. The optical conductivity of the AZO thin films also increases with increasing photon energy

  3. Competition between (001) and (111) MgO thin film growth on Al-doped ZnO by oxygen plasma assisted pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, Bo; Yang, Qiguang; Walker, Brandon; Gonder, Casey A.; Romain, Gari C.; Mundle, Rajeh; Bahoura, Messaoud; Pradhan, A. K. [Center for Materials Research, Norfolk State University, Norfolk, Virginia 23504 (United States)

    2013-06-07

    We report on the study of epitaxial MgO thin films on (0001) Al-doped ZnO (Al: ZnO) underlayers, grown by oxygen plasma assisted pulsed laser deposition technique. A systematic investigation of the MgO thin films was performed by X-ray diffraction and atomic force microscopy, along with the current-voltage characteristics. A distinguished behavior was observed that the preferred MgO orientation changes from (111) to (001) in the films as the growth temperature increases. Two completely different in-plane epitaxial relationships were also determined from X-ray diffraction as: [110]MgO//[1120]Al: ZnO and [110]MgO//[1100]Al: ZnO for (001) MgO with 60 Degree-Sign rotated triplet domains, and [110]MgO//[1120]Al: ZnO for (111) MgO with 180 Degree-Sign rotated twin. The pronounced temperature dependence indicates a reconciliation of the nucleation driving forces among surface, interfacial, and strain energy for heteroepitaxy of cubic MgO on hexagonal Al: ZnO. The related interfacial atomic registry is considered to be important to the formation of unusual (001) MgO on hexagonal crystals. In addition, the electrical characterization revealed a dramatic reduction of the leakage current in (001) MgO thin films, whereas the small grain size of (111) MgO is identified by atomic force microscopy as a main cause of large leakage current.

  4. Atomic layer deposition of undoped and Al-doped ZnO thin films using the Zn alkoxide precursor methylzinc isopropoxide.

    Science.gov (United States)

    An, Ki-Seok; Cho, Wontae; Lee, Byung Kook; Lee, Sun Sook; Kim, Chang Gyoun

    2008-09-01

    Undoped and Al-doped ZnO thin films have been prepared by atomic layer deposition (ALD) using the Zn precursor methylzinc isopropoxide [MZI, (CH3)Zn(OCH(CH3)2)] with water (H2O). Dimethylaluminum isopropoxide (DMAI) was used as an Al precursor. The self-limiting ALD process via alternate surface reactions of MZI and H2O was confirmed by thickness measurements of the ZnO films with varying MZI supply time and numbers of MZI-H2O ALD cycles. Under optimal reaction conditions, the growth rate of the ZnO films was 1.9 to approximately 2.0 A/cycle in the substrate temperature range of 160 to approximately 200 degrees C and the maximum growth rate reached about 2.58 A/cycle at 240 degrees C. Room temperature photoluminescence (PL) measurements revealed a strong free excitonic peak at 3.27 eV with almost negligible deep level emission. Resistivities of ZnO films were measured to be 5 x 10(-3) to approximately 3.2 x 10(-3) omega cm depending on the substrate temperature. By Al-doping, the resistivity was minimized to approximately 1.35 x 10(-4) cm.

  5. Investigation of textured Al-doped ZnO thin films using chemical wet-etching methods

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Wei-Lun; Huang, Kuo-Chan [Institute of Microelectronics, Department of Electrical Engineering, National Cheng Kung University, 1 University Road, Tainan 701, Taiwan (China); Yeh, Chih-Hung [R and D Center, NexPower Technology Corporation, Taichung 421, Taiwan (China); Hung, Chen-I [Department of Mechanical Engineering, National Cheng Kung University, Tainan 701, Taiwan (China); Houng, Mau-Phon, E-mail: mphoung@eembox.ncku.edu.tw [Institute of Microelectronics, Department of Electrical Engineering, National Cheng Kung University, 1 University Road, Tainan 701, Taiwan (China)

    2011-05-16

    Research highlights: {yields} The effects of deposition temperature on the electrical properties of ZnO:Al film is revealed in this study. {yields} The optical properties of textured ZnO:Al films etched in diluted HCl, H{sub 3}PO{sub 4} and HNO{sub 3} were studied. {yields} The effects of etching parameters on the optical and electrical properties of ZnO:Al film are investigated in this study. {yields} The diluted HNO{sub 3} is the best candidate to fabricate excellent textured surface with the highest haze ratio in this study. - Abstract: In this study, the optical properties and morphologies of Al-doped ZnO (AZO) films textured by the chemical wet-etching method with three different acid species are investigated. An initial AZO film is sputtered on a glass substrate by rf magnetron sputtering. The film surface was then textured by wet-etching using diluted HCl, HNO{sub 3} or H{sub 3}PO{sub 4}. The average transmittance of all the post-treated ZnO:Al films remains around 75-80% as measured by a UV-vis analyzer. A haze ratio calculation shows that the light scattering properties can be significantly controlled by varying the etchant species, acid concentration, and etching time. Atomic force microscopy (AFM) was used to find the average roughness of the textured AZO films. In this study, the HNO{sub 3} etchant gives the highest haze ratio of 49.2% at a wavelength of 550 nm. The textured ZnO:Al films with an electrical resistivity of 5.47 x 10{sup -4} {Omega}-cm, carrier concentrations of 3.98 x 10{sup 20} cm{sup -3} and mobility of 28.7 cm{sup 2} V{sup -1} s{sup -1}, can be obtained when etched in diluted HNO{sub 3} for 60 s. It is found that the chemical wet-etched AZO glass substrate appears to be helpful in enhancing the short circuit current (J{sub sc}) when applied on silicon thin film solar cells.

  6. Effect of Al-doped on physical properties of ZnO Thin films grown by spray pyrolysis on SnO2: F/glass

    Directory of Open Access Journals (Sweden)

    Castagné M.

    2012-06-01

    Full Text Available Transparent conducting thin films of aluminum-doped zinc oxide (ZnO:Al have been deposited on SnO2:F/glass by the chemical spray technique, starting from zinc acetate (CH3CO22Zn.2H2O and aluminum chloride AlCl3. The effect of changing the aluminum-to-zinc ratio y from 0 to 3 at.%, has been thoroughly investigated. It was found that the optical and electrical properties of Al doped ZnO films improved with the addition of aluminum in the spray solution until y=2%. At this Al doping percentage, the thin layers have a resistivity equal to 4.1 × 10−4 Ω.cm and a transmittance of about 90 % in the region [600-1000] nm. XRD patterns confirm that the films have polycristalline nature and a wurtzite (hexagonal structure which characterized with (100, (002 and (101 principal orientations. The undoped films have (002 as the preferred orientation but Al doped ones have (101 as the preferred orientation. Beyond y= 1%, peak intensities decrease considerably.

  7. Structural, optical, morphological and electrical properties of undoped and Al-doped ZnO thin films prepared using sol—gel dip coating process

    Science.gov (United States)

    Boukhenoufa, N.; Mahamdi, R.; Rechem, D.

    2016-11-01

    In this work, sol—gel dip-coating technique was used to elaborate ZnO pure and ZnO/Al films. The impact of Al-doped concentration on the structural, optical, surface morphological and electrical properties of the elaborated samples was investigated. It was found that better electrical and optical performances have been obtained for an Al concentration equal to 5%, where the ZnO thin films exhibit a resistivity value equal to 1.64104 Ω·cm. Moreover, highest transparency has been recorded for the same Al concentration value. The obtained results from this investigation make the developed thin film structure a potential candidate for high optoelectronic performance applications.

  8. Investigation of the biaxial stress of Al-doped ZnO thin films on a flexible substrate with RF magnetron sputtering

    Science.gov (United States)

    Huang, Kuo-Ting; Chen, Hsi-Chao; Cheng, Po-Wei; Chang, Jhe-Ming

    2016-01-01

    Transparent conductive Al-doped ZnO (AZO) thin films were deposited onto poly(ethylene terephthalate) (PET) substrate, using the radio frequency (RF) magnetron sputtering method. The residual stress of flexible electronics was investigated by a double beam shadow moiré interferometer with phase shifting interferometry (PSI). Moreover, the biaxial stress of AZO thin films can be graphically represented by using Mohr’s circle of stress. The residual stress of AZO thin films becomes more compressive with the increase in sputtering power. The maximum residual stress is -1115.74 MPa, and the shearing stress is 490.57 MPa at a sputtering power of 200 W. The trends of residual stress were evidenced by the X-ray diffraction (XRD) patterns and optical properties of AZO thin films. According to the evaluation results of the refractive index and the extinction coefficient, the AZO thin films have better quality when the sputtering power less than 100 W.

  9. Influence of Postdeposition Cooling Atmosphere on Thermoelectric Properties of 2% Al-Doped ZnO Thin Films Grown by Pulsed Laser Deposition

    Science.gov (United States)

    Saini, S.; Mele, P.; Honda, H.; Matsumoto, K.; Miyazaki, K.; Luna, L. Molina; Hopkins, P. E.

    2015-06-01

    We have investigated the thermoelectric properties of 2% Al-doped ZnO (AZO) thin films depending on the postdeposition cooling atmosphere [in oxygen pressure (AZO-O) or vacuum (AZO-V)]. Thin films were grown by pulsed laser deposition on sapphire () substrates at various deposition temperatures ( to ). All films were c-axis oriented. The electrical conductivity of AZO-V thin films was higher than that of AZO-O thin films across the whole temperature range from 300 K to 600 K, due to the optimal carrier concentration () of AZO-V samples. Furthermore, the thermoelectric performance of AZO-V films increased with the deposition temperature; for instance, the highest power factor of and dimensionless figure of merit of 0.07 at 600 K were found for AZO-V thin film deposited at.

  10. Electronic structure of Al-doped ZnO transparent conductive thin films studied by x-ray absorption and emission spectroscopies

    Energy Technology Data Exchange (ETDEWEB)

    Huang, W. H.; Sun, S. J.; Chiou, J. W. [Department of Applied Physics, National University of Kaohsiung, Kaohsiung 811, Taiwan (China); Chou, H. [Department of Physics, National Sun Yat-sen University, Kaohsiung 804, Taiwan (China); Chan, T. S.; Lin, H.-J. [National Synchrotron Radiation Research Center, Hsinchu 300, Taiwan (China); Kumar, Krishna [Department of Electrical and Computer Engineering, University of Waterloo, Ontario N2L 3G1 (Canada); Guo, J.-H. [Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)

    2011-11-15

    This study used O K-, Zn L{sub 3}-, Zn K-, and Al K-edges x-ray absorption near-edge structure (XANES) and O K-edge x-ray emission spectroscopy (XES) measurements to investigate the electronic structure of transparent Al-doped ZnO (AZO) thin film conductors. The samples were prepared on glass substrates at a low temperature near 77 K by using a standard RF sputtering method. High-purity Ne (5N) was used as the sputtering gas. The crystallography of AZO thin films gradually transformed from the ZnO wurtize structure to an amorphous structure during sample deposition, which suggests the suitability to grow on flexible substrates, eliminating the severe degradation due to fragmentation by repeated bending. The O K- and Zn L{sub 3}-edges XANES spectra of AZO thin films revealed a decrease in the number of both O 2p and Zn 3d unoccupied states when the pressure of Ne was increased from 5 to 100 mTorr. In contrast, Al K-edges XANES spectra showed that the number of unoccupied states of Al 3p increased in conjunction with the pressure of Ne, indicating an electron transfer from Al to O atoms, and suggesting that Al doping increases the negative effective charge of oxygen ions. XES and XANES spectra of O 2p states at the O K-edge also revealed that Al doping not only raised the conduction-band-minimum, but also increased the valence-band-maximum and the band-gap. The results indicate that the reduction in conductivity of AZO thin films is due to the generation of ionic characters, the increase in band-gap, and the decrease in density of unoccupied states of oxygen.

  11. Dopant-induced bandgap shift in Al-doped ZnO thin films prepared by spray pyrolysis

    Science.gov (United States)

    Hung-Chun Lai, Henry; Basheer, Tahseen; Kuznetsov, Vladimir L.; Egdell, Russell G.; Jacobs, Robert M. J.; Pepper, Michael; Edwards, Peter P.

    2012-10-01

    A series of 1 at. % Al-doped ZnO (AZO) films were deposited onto glass substrates by a spray pyrolysis technique. We find that the observed blue shift in the optical bandgap of 1% AZO films is dominated by the Burstein Moss effect. The Fermi level for an 807 nm thick AZO film rose by some 0.16 eV with respect to the edge of the conduction band. By controlling the film thickness, all AZO films exhibit the same lattice strain values. The influence of strain-induced bandgap shift was excluded by selecting films with nearly the same level of bandgap volume-deformation potentials, and the differences in out-plain strain and in-plain stress remained effectively constant.

  12. Effect of the RF sputtering power on microstructural, optical and electrical properties of Al doped ZnO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Spadoni, A.; Addonizio, M.L., E-mail: marialuisa.addonizio@enea.it

    2015-08-31

    ZnO:Al (AZO) thin films have been deposited by radio frequency (RF) magnetron sputtering and RF power applied to the target has been varied in the range 600–1200 W. RF power effect on structural, electrical and optical properties was investigated and the relationship existing between these properties and the film lattice defect distribution was discussed. At the increasing of the RF power it was found that AZO films, having a preferential growth orientation along (002) direction, showed a decrease of the lattice distance indicating a less defected structure. Furthermore, at the increase of the RF power a higher optical absorption by free carriers, coupled with an increase of the band gap value, was observed. Resistivity varied from 1.1 × 10{sup −3} Ω cm at 600 W down to a minimum value of 5.6 × 10{sup −4} Ω cm at 1200 W, whereas the carrier density increased up to 1 × 10{sup 21} cm{sup −3}. Lattice defect variation of AZO films was analyzed by photoluminescence (PL) measurements. Presence and amount of different lattice defects were evaluated for AZO films deposited at different RF powers. At 600 W the film structure was dominated by zinc vacancies (V{sub Zn}), whereas for higher RF power the PL band associated with V{sub Zn} decreased and interstitial oxygen (O{sub i}) band remarkably increased. PL analysis revealed that extrinsic Al doping is the dominant effect on the conductivity enhancement. It was hypothesized that at higher RF power a more effective diffusion phenomenon can give more effective Al doping and less amount of zinc vacancies. As a consequence, Al atoms are more effectively trapped into the structure. - Highlights: • ZnO:Al thin films have been deposited by RF sputtering technique. • The effect of the sputtering power on film properties has been investigated. • Electrical, optical and structural characterization has been carried out. • PL analysis revealed lattice defect chemistry variation at the increase of RF power.

  13. Effects of intermittent atomization on the properties of Al-doped ZnO thin films deposited by aerosol-assisted chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Linjie; Wang, Lixin [Hebei Key Laboratory of Applied Chemistry, Yanshan University, Qinhuangdao 066004 (China); Qin, Xiujuan, E-mail: qinxj@ysu.edu.cn [Hebei Key Laboratory of Applied Chemistry, Yanshan University, Qinhuangdao 066004 (China); Cui, Li [Hebei Key Laboratory of Applied Chemistry, Yanshan University, Qinhuangdao 066004 (China); Shao, Guangjie [Hebei Key Laboratory of Applied Chemistry, Yanshan University, Qinhuangdao 066004 (China); State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004 (China)

    2016-04-30

    Al-doped ZnO (AZO) thin films were prepared on glass substrates with different atomization interval times by aerosol-assisted chemical vapor deposition method. The structure, morphology, and optical and electrical properties were investigated by X-ray diffractometer, atomic force microscope, UV-vis double beam spectrophotometer and 4 point probe method. ZnO thin films exhibited strong growth orientation along the (002) plane and the crystalline was affected by the atomization interval time. All the films had high transmittance and the films with interval times of 2 min and 4 min had good haze values for the transparent conducting oxide silicon solar cell applications. The AZO thin film had the best optical and electrical properties when the atomization interval time was 4 min. This is very important for the optoelectronic device applications. The surface morphology of AZO films depended on the atomization interval time. - Highlights: • Intermittent atomization is proved to be an effective measure. • Atomization interval time has an important influence on the crystallinity of films. • The surface morphology of ZnO films depends on atomization interval time. • Different hazes can be obtained by changing the atomization interval time.

  14. Characterization of Al-Doped ZnO Transparent Conducting Thin Film Prepared by Off-Axis Magnetron Sputtering

    Directory of Open Access Journals (Sweden)

    Sin-Liang Ou

    2016-01-01

    Full Text Available The off-axis sputtering technique was used to deposit Al-doped ZnO (AZO films on glass substrates at room temperature. For the illustration of the sample position in the sputtering chamber, the value of R/r is introduced. Here, r is the radius of AZO target and R is the distance between the sample and the center of substrate holder. A systematic study for the effect of deposition parameters on structural, optical, and electrical properties of AZO films has been investigated in detail. As the sample position of R/r is fixed at 1.8, it is found that the as-deposited AZO film has relatively low resistivity of 2.67 × 10−3 Ω-cm and high transmittance above 80% in the visible region. Additionally, after rapid thermal annealing (RTA at 600°C with N2 atmosphere, the resistivity of this AZO film can be further reduced to 1.19 × 10−3 Ω-cm. This indicates the AZO films prepared by off-axis magnetron sputtering and treated via the appropriate RTA process have great potential in optoelectronic applications.

  15. Reflective second harmonic generation near resonance in the epitaxial Al-doped ZnO thin film.

    Science.gov (United States)

    Liu, S W; Weerasinghe, J L; Liu, J; Weaver, J; Chen, C L; Donner, W; Xiao, Min

    2007-08-20

    The second harmonic (SH) generation from the highly epitaxial Al-doped ZnO film on sapphire was measured, using the femtosecond Ti:Sapphire laser at the near-resonant SH wavelength, in reflection geometry to avoid the sapphire's contribution in the conventional Maker fringes technique. By investigating SH intensities as a function of the azimuthal angle along the film's normal, we found that the sapphire substrate had a negligible contribution to the reflective SH signal and the film had a pure and well-aligned c-domain. We also developed a new method to calculate the component's ratios of the nonlinear susceptibility tensor by analyzing the polarization diagrams of SH intensities under the incidence with two different angles. The ratios indicate that Kleinman's symmetry is broken due to the absorption at SH wavelength and the dominant component of the nonlinear susceptibility tensor is d(33). Calibration using the Z-cut quartz shows a possible overestimate of the nonlinear response by Maker fringes technique.

  16. Effect of Al doping on microstructure and optical band gap of ZnO thin film synthesized by successive ion layer adsorption and reaction

    Indian Academy of Sciences (India)

    S Mondal; S R Bhattacharyya; P Mitra

    2013-02-01

    Thin films of pure and aluminum-doped zinc oxide (AZO) were deposited on glass substrates from ammonium zincate bath following a chemical dipping technique called successive ion layer adsorption and reaction (SILAR). Characterization techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy-dispersive X-rays (EDX) were used to investigate the effect of Al doping on the microstructure of AZO films. Particle size analysis using X-ray line broadening shows marginally increasing trend with increasing Al impurity. The average particle size for pure ZnO is 22.75 nm. It increases to 24.26 nm for 1% AZO film and 25.13 nm for 2% AZO film. Incorporation of Al was confirmed from elemental analysis using EDX. SEM micrograph shows that pure ZnO particles are spherical shaped. However, AZO films show particles with off-spherical shape with compact interconnected grains. The value of band gap for pure ZnO is 3.229 eV and it increases to 3.29 eV for 1% AZO indicating a blue-shift for 1% AZO film. However, for 2% AZO film, a decrease in band gap compared to pure ZnO is observed indicating a red-shift of fundamental absorption edge. Electrical resistance shows an initial decrease with increasing Al content. With further enhancement of Al incorporation, the resistance increases.

  17. Biaxial stress and optoelectronic properties of Al-doped ZnO thin films deposited on flexible substrates by radio frequency magnetron sputtering.

    Science.gov (United States)

    Chen, Hsi-Chao; Cheng, Po-Wei; Huang, Kuo-Ting

    2017-02-01

    Transparent conductive Al-doped ZnO (AZO) thin films were deposited on polyethylene terephthalate (PET) and polycarbonate (PC) substrates using radio frequency (RF) magnetron sputtering. The biaxial stress was measured with a double beam shadow moiré interferometer, and x-ray diffraction (XRD) was used to investigate the crystal orientation of ZnO. The substrate temperature was varied from room temperature to 150°C in steps of 25°C. The experimental results showed that the residual and shearing stresses increased with the increase in substrate temperature. The residual stress can be separated into principle and shearing stresses by Mohr's circle rule, and the shearing stress (tensile stress) was different from the compressive stress of the residual stress. However, the optimal substrate temperatures for PET and PC were 75°C and 100°C, and the shearing stresses were 424.82 and 543.68 MPa, respectively. AZO/PET and AZO/PC thin films cracked at substrate temperatures of 75°C and 100°C, respectively. AZO/PET thin film at a substrate temperature of 100°C had a resistivity low to the order of 10-3  Ω-cm.

  18. Correlations between 1/f noise and thermal treatment of Al-doped ZnO thin films deposited by direct current sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Barhoumi, A., E-mail: amira-barhoumi@yahoo.fr; Guermazi, S. [University of Sfax, Research Unit: PMISI, Faculty of Science Sfax, Route de la Soukra Km 3.5-B.P. n° 1171-3000 Sfax (Tunisia); Leroy, G.; Gest, J.; Carru, J. C. [University Lille North of France, ULCO, UDSMM, 62228 Calais (France); Yang, L. [Hebei Union University, Electrical Engineering, 46 Xinhua Road, Tangshan 063009, Hebei (China); Boughzala, H. [University of Tunis El-Manar, Faculty of Science Tunis,, Laboratory of Crystallochemistry, 1060 Tunis (Tunisia); Duponchel, B. [University Lille North of France, ULCO, UDSMM, 59140 Dunkerque (France)

    2014-05-28

    Al-doped ZnO thin films (AZO) have been deposited on amorphous glass substrates by DC sputtering at different substrate temperatures T{sub s}. X-Ray diffraction results reveal that AZO thin films have a hexagonal wurtzite structure with (002) preferred orientation. (002) peaks indicate that the crystalline structure of the films is oriented with c-axis perpendicular to the substrate. Three-dimensional (3D) atomic force microscopy images of AZO thin films deposited on glass substrate at 200 °C, 300 °C, and 400 °C, respectively, shows the improvement of the crystallinity and the homogeneity of AZO thin films with T{sub s} which is in agreement with the noise measurements. The noise was characterized between 1 Hz and 100 kHz and we have obtained 1/f spectra. The noise is very sensitive to the crystal structure especially to the orientation of the crystallites which is perpendicular to the substrate and to the grain boundaries which generate a high current flow and a sharp increase in noise. Through time, R{sub sh} and [αμ]{sub eff} increase with the modification of the crystallinity of AZO thin films. Study of noise aging shows that the noise is more sensitive than resistivity for all AZO thin films.

  19. Room temperature deposition of Al-doped ZnO thin films on glass by RF magnetron sputtering under different Ar gas pressure

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Deok Kyu, E-mail: maruchi111@naver.com [Brain Korea 21 Chungbuk Information Technology Center, Chungbuk National University, Cheongju 361-763, Chungbuk (Korea, Republic of); Kim, Hong Bae [Division of Electronics and Information Engineering, Cheongju University, Cheongju 360-764, Chungbuk (Korea, Republic of)

    2011-01-12

    Research highlights: > The level of oxygen vacancies significantly decreases with increasing Ar gas pressure. > The number of oxygen vacancies decreases, and the number of oxygen atom in the lattice increases. > The lattice scattering increases and the mobility is reduced by the increased lattice scattering. > Finally, the reduced mobility increases the resistivity of the AZO thin films. > The mobility plays a major role in the conduction behavior of AZO thin films deposited at room temperature. - Abstract: Al-doped ZnO (AZO) thin films were deposited on glass substrates at room temperature by RF magnetron sputtering. The effects of Ar gas pressure on the structural, optical, and electrical properties were investigated. As the Ar gas pressure increased, the resistivities of the AZO thin films increased, the mobilities decreased, and the carrier concentrations were constant. X-ray photoelectron spectroscopy (XPS) showed that higher Ar gas pressures promoted O-Zn bond formation and reduced the number of oxygen vacancies. The reduction in mobility, which increased the resistivity, was attributed to increased lattice scattering by the oxygen atoms. In AZO thin films deposited at room temperature, the conduction characteristics are primarily influenced by the mobility.

  20. Al-doped ZnO nanofilms: Synthesis and characterization

    Energy Technology Data Exchange (ETDEWEB)

    Huczko, A.; Dabrowska, A. [Department of Chemistry, Warsaw University, Warsaw (Poland); Madhup, D.K. [Department of Physics, Kathmandu University, Dhulikhel (Nepal); College of Biomedical Engineering and Applied Sciences, Hadigaun, Kathmandu (Nepal); Subedi, D.P.; Chimouriya, S.P. [Department of Physics, Kathmandu University, Dhulikhel (Nepal)

    2010-12-15

    Al-doped and un-doped ZnO nanofilms on quartz substrate were obtained by ultrasonic spray pyrolysis of salt solutions (mole concentration of Al within 0-10%). The films were characterized by Scanning electron microscopy (SEM), X-ray diffraction (XRD), Atomic force microscopy (AFM) and UV spectroscopy to study the morphology and optical properties. The optical studies showed that the increase in Al within ZnO thin layer increases its band gap energy. The obtained value of band gap energy is very close to the determined oscillation energy. However, the dispersion energy is nearly half of band gap energy value. (Copyright copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  1. Decoration of PbS nanoparticles on Al-doped ZnO nanorod array thin film with hydrogen treatment as a photoelectrode for solar water splitting

    Energy Technology Data Exchange (ETDEWEB)

    Hsu, Chih-Hsiung; Chen, Chao-Hong [Department of Chemical Engineering and Research Center for Energy Technology and Strategy, National Cheng Kung University, Tainan 701, Taiwan, ROC (China); Chen, Dong-Hwang, E-mail: chendh@mail.ncku.edu.tw [Department of Chemical Engineering and Research Center for Energy Technology and Strategy, National Cheng Kung University, Tainan 701, Taiwan, ROC (China)

    2013-03-25

    Highlights: ► AZO nanorod array thin film is used as a photoanode for solar water splitting. ► Hydrogen treatment and sensitization by PbS nanoparticles enhance photocurrent. ► A novel ITO/FTO-free composite photoelectrode is developed. ► The pre-fabrication and use of an extra TCO thin film substrate is unnecessary. -- Abstract: Al-doped ZnO (AZO) nanorod arrays thin film with hydrogen treatment is directly used as a photoelectrode for solar water splitting without an extra transparent conducting oxide (TCO) thin film because it possesses the functions of TCO thin film and photoactive 1-dimensional nanostructured semiconductor simultaneously. To enhance the absorption in the visible region, PbS nanoparticles decorated the AZO nanorods via successive ionic layer adsorption and reaction route. The PbS nanoparticles have a face-centered cubic structure and their decoration does not destroy the 1-dimensional morphology of AZO nanorod arrays. With increasing the cycle number of PbS nanoparticles decoration, the grain size and loading of PbS nanoparticles become larger gradually which leads to lower energy bandgap and stronger absorption. A maximum photocurrent density of 1.65 mW cm{sup −2} is obtained when the cycle number is 20, which is much higher than those without PbS nanoparticles sensitization or hydrogen treatment. This demonstrates that the AZO nanorod array thin film with hydrogen treatment can be directly used as a photoelectrode without an extra TCO thin film. Because the use of expensive metals can be avoided and the pre-fabrication of TCO thin film substrate is necessary no more, the fabrication of such a composite photoelectrode becomes simple and low-cost. So, it has great potentials in solar water splitting after sensitization by quantum dots capable of visible light absorption.

  2. Transparent conductive oxide layer with monolayer closed-pack Al-doped ZnO spheres and their application to a-Si thin-film solar cells.

    Science.gov (United States)

    Lo, Shih-Shou; Lin, Chen-Yu; Jan, Der-Jun

    2011-09-15

    We report a new (to the best of our knowledge) transparent conductive oxide (TCO) layer with a monolayer of closed-pack Al-doped ZnO (AZO) spheres partly embedded in an AZO thin film. The average transmittance and haze ratio in the wavelength range of 380-800 nm achieves 65% and 55%, respectively, when AZO spheres with a diameter of 500 nm are embedded in a thickness of 240 nm AZO thin films. The a-Si thin-film solar cell with a regular p-i-n TCO structure is demonstrated. Under air mass 1.5 global illumination, conversion efficiencies of 5.6%, a fill factor of 0.55, V(oc) of 0.81 V, and a J(sc) of 2.44 mA/cm² are obtained. The Letter helps us to open up potential applications of a new TCO in advanced solar cells and light-emitting diodes.

  3. Enhanced photovoltaic performance of quantum dot-sensitized solar cell fabricated using Al-doped ZnO nanorod electrode

    Science.gov (United States)

    Raja, M.; Muthukumarasamy, N.; Velauthapillai, Dhayalan; Balasundrapraphu, R.; Senthil, T. S.; Agilan, S.

    2015-04-01

    ZnO and Al doped ZnO nanorods have been successfully synthesized on ITO substrate via solgel dip coating method without using any catalyst. The X-ray diffraction studies showed that the Al doped ZnO samples are of hexagonal wurtzite structure. The Al ions were successfully incorporated into the ZnO lattice. Scanning electron microscopy images reveal that the average diameter of ZnO nanorods and Al doped ZnO nanorods are ∼300 nm and ∼200 nm respectively. The energy dispersive X-ray (EDS) analysis confirmed the presence Al in the ZnO thin films. The CdS quantum dot sensitized Al doped ZnO solar cell exhibited a power conversion efficiency of 1.5%.

  4. Characteristics of sputtered Al-doped ZnO films for transparent electrodes of organic thin-film transistor

    Energy Technology Data Exchange (ETDEWEB)

    Park, Yong Seob, E-mail: yongspark2011@gmail.com [Department of Advanced Materials Engineering for Information and Electronics, Kyung Hee University, Yongin-si, 446-701 (Korea, Republic of); Department of Electrical and Electronic Engineering, Seonam University, Asan-si, 336-922 (Korea, Republic of); Kim, Han-Ki [Department of Electrical and Electronic Engineering, Seonam University, Asan-si, 336-922 (Korea, Republic of)

    2011-09-01

    Aluminum-doped ZnO (AZO) thin-films were deposited with various RF powers at room temperature by radio frequency (RF) magnetron sputtering method. The electrical properties of the AZO film were improved with the increasing RF power. These results can be explained by the improvement of the crystallinity in the AZO film. We fabricated the organic thin-film transistor (OTFT) of the bottom gate structure using pentacene active and poly-4-vinyl phenol gate dielectric layers on the indium tin oxide gate electrode, and estimated the device properties of the OTFTs including drain current-drain voltage (I{sub D}-V{sub D}), drain current-gate voltage (I{sub D}-V{sub G}), threshold voltage (V{sub T}), on/off ratio and field effect mobility. The AZO film that grown at 160 W RF power exhibited low resistivity (1.54 x 10{sup -3} {Omega}.cm), high crystallinity and uniform surface morphology. The pentacene thin-film transistor using the AZO film that's fabricated at 160 W RF power exhibited good device performance such as the mobility of 0.94 cm{sup 2}/V s and the on/off ratio of {approx} 10{sup 5}. Consequently, the performance of the OTFT such as larger field-effect carrier mobility was determined the conductivity of the AZO source/drain (S/D) electrode. AZO films prepared at room temperature by the sputtering method are suitable for the S/D electrodes in the OTFTs.

  5. Bi-layer channel structure-based oxide thin-film transistors consisting of ZnO and Al-doped ZnO with different Al compositions and stacking sequences

    Science.gov (United States)

    Cho, Sung Woon; Yun, Myeong Gu; Ahn, Cheol Hyoun; Kim, So Hee; Cho, Hyung Koun

    2015-03-01

    Zinc oxide (ZnO)-based bi-layers, consisting of ZnO and Al-doped ZnO (AZO) layers grown by atomic layer deposition, were utilized as the channels of oxide thin-film transistors (TFTs). Thin AZO layers (5 nm) with different Al compositions (5 and 14 at. %) were deposited on top of and beneath the ZnO layers in a bi-layer channel structure. All of the bi-layer channel TFTs that included the AZO layers showed enhanced stability (Δ V Th ≤ 3.2 V) under a positive bias stress compared to the ZnO single-layer channel TFT (Δ V Th = 4.0 V). However, the AZO/ZnO bi-layer channel TFTs with an AZO interlayer between the gate dielectric and the ZnO showed a degraded field effect mobility (0.3 cm2/V·s for 5 at. % and 1.8 cm2/V·s for 14 at. %) compared to the ZnO single-layer channel TFT (5.5 cm2/V·s) due to increased scattering caused by Al-related impurities near the gate dielectric/channel interface. In contrast, the ZnO/AZO bi-layer channel TFTs with an AZO layer on top of the ZnO layer exhibited an improved field effect mobility (7.8 cm2/V·s for 14 at. %) and better stability. [Figure not available: see fulltext.

  6. Comparative studies of Al-doped ZnO and Ga-doped ZnO transparent conducting oxide thin films

    OpenAIRE

    Jun, Min-Chul; Park, Sang-Uk; Koh, Jung-Hyuk

    2012-01-01

    We have investigated the influences of aluminum and gallium dopants (0 to 2.0 mol%) on zinc oxide (ZnO) thin films regarding crystallization and electrical and optical properties for application in transparent conducting oxide devices. Al- and Ga-doped ZnO thin films were deposited on glass substrates (corning 1737) by sol–gel spin-coating process. As a starting material, AlCl3⋅6H2O, Ga(NO3)2, and Zn(CH3COO)2⋅2H2O were used. A lowest sheet resistance of 3.3 × 103 Ω/□ was obtained for the GZO ...

  7. Enhanced Performance in Al-Doped ZnO Based Transparent Flexible Transparent Thin-Film Transistors Due to Oxygen Vacancy in ZnO Film with Zn-Al-O Interfaces Fabricated by Atomic Layer Deposition.

    Science.gov (United States)

    Li, Yang; Yao, Rui; Wang, Huanhuan; Wu, Xiaoming; Wu, Jinzhu; Wu, Xiaohong; Qin, Wei

    2017-04-05

    Highly conductive and optical transparent Al-doped ZnO (AZO) thin film composed of ZnO with a Zn-Al-O interface was fabricated by thermal atomic layer deposition (ALD) method. The as-prepared AZO thin film exhibits excellent electrical and optical properties with high stability and compatibility with temperature-sensitive flexible photoelectronic devices; film resistivity is as low as 5.7 × 10(-4) Ω·cm, the carrier concentration is high up to 2.2 × 10(21) cm(-3). optical transparency is greater than 80% in a visible range, and the growth temperature is below 150 °C on the PEN substrate. Compared with the conventional AZO film containing by a ZnO-Al2O3 interface, we propose that the underlying mechanism of the enhanced electrical conductivity for the current AZO thin film is attributed to the oxygen vacancies deficiency derived from the free competitive growth mode of Zn-O and Al-O bonds in the Zn-Al-O interface. The flexible transparent transistor based on this AZO electrode exhibits a favorable threshold voltage and Ion/Ioff ratio, showing promising for use in high-resolution, fully transparent, and flexible display applications.

  8. Room-temperature deposition of transparent conductive Al-doped ZnO thin films using low energy ion bombardment

    Energy Technology Data Exchange (ETDEWEB)

    Jin, C.G.; Yu, T.; Wang, F.; Wu, X.M. [Soochow University, Department of Physics, Soochow (China); Soochow University, The Key Laboratory of Thin Films of Jiangsu, Soochow (China); Wu, Z.F. [Yancheng Institute of Technology, Yancheng (China); Wu, M.Z. [Soochow University, Department of Physics, Soochow (China); Wang, Y.Y.; Yu, Y.M. [Wenzheng College of Soochow University, Soochow (China); Zhuge, L.J. [Soochow University, The Key Laboratory of Thin Films of Jiangsu, Soochow (China); Soochow University, Analysis and Testing Center, Soochow (China)

    2012-03-15

    Al-doped zinc oxide (AZO) films are prepared on quartz substrates by dual-ion-beam sputtering deposition at room temperature ({proportional_to}25 C). An assisting argon ion beam (ion energy E{sub i} =0-300 eV) directly bombards the substrate surface to modify the properties of AZO films. The effects of assisted-ion beam energy on the characteristics of AZO films were investigated in terms of X-ray diffraction, atomic force microscopy, Raman spectra, Hall measurement and optical transmittance. With increasing assisting-ion beam bombardment, AZO films have a strong improved crystalline quality and increased radiation damage such as oxygen vacancies and zinc interstitials. The lowest resistivity of 4.9 x 10 {sup -3}{omega} cm and highest transmittance of above 85% in the visible region were obtained under the assisting-ion beam energy 200 eV. It was found that the bandgap of AZO films increased from 3.37 to 3.59 eV when the assisting-ion beam energy increased from 0 to 300 eV. (orig.)

  9. Advanced properties of Al-doped ZnO films with a seed layer approach for industrial thin film photovoltaic application

    Energy Technology Data Exchange (ETDEWEB)

    Dewald, Wilma, E-mail: wilma.dewald@ist.fraunhofer.de [Fraunhofer Institute for Surface Engineering and Thin Films IST, Bienroder Weg 54E, 38108 Braunschweig (Germany); Sittinger, Volker; Szyszka, Bernd [Fraunhofer Institute for Surface Engineering and Thin Films IST, Bienroder Weg 54E, 38108 Braunschweig (Germany); Säuberlich, Frank; Stannowski, Bernd [Sontor GmbH, OT Thalheim, Sonnenallee 7-11, 06766 Bitterfeld-Wolfen (Germany); Köhl, Dominik; Ries, Patrick; Wuttig, Matthias [I. Physikalisches Institut (IA), RWTH Aachen, Sommerfeldstraße 14, 52074 Aachen (Germany)

    2013-05-01

    Currently sputtered Al-doped ZnO films are transferred to industry for the application in thin film silicon solar modules. These films are known to easily form light trapping structures upon etching which are necessary for absorbers with low absorbance such as μc-Si. Up to now the best structures for high efficiency thin film silicon solar cells were obtained by low rate radio frequency (r.f.) sputtering of ceramic targets. However, for industrial application a high rate process is essential. Therefore a seed layer approach was developed to increase the deposition rate while keeping the desired etch morphology and electrical properties. Aluminum doped ZnO films were deposited dynamically by direct current (d.c.) magnetron sputtering from a ceramic ZnO:Al{sub 2}O{sub 3} target (1 wt.%) onto an additional seed layer prepared by r.f. sputtering. ZnO:Al films were investigated with respect to their optical and electrical properties as well as the morphology created after etching for a-Si/μc-Si solar cells. Additionally atomic force microscopy, scanning electron microscopy, X-ray diffraction and Hall measurements were performed, comparing purely r.f. or d.c. sputtered films with d.c. sputtered films on seed layers. With the seed layer approach it was possible to deposit ZnO:Al films with a visual transmittance of 83.5%, resistivity of 295 μΩ cm, electron mobility of 48.9 cm{sup 2}/Vs and electron density of 4.3 · 10{sup 20} cm{sup −3} from a ceramic target at 330 °C. Etch morphologies with 1 μm lateral structure size were achieved. - Highlights: ► Seed layer approach for dynamic sputter deposition of enhanced quality ZnO:Al. ► A thin radio frequency sputtered ZnO:Al layer assists film nucleation on glass. ► Electron mobility was increased up to 49 cm{sup 2}/Vs due to quasi-epitaxial film growth. ► Etch morphology exhibits 1 μm wide craters for light trapping in solar cells. ► The concept was transferred to a seed layer sputtered with direct current.

  10. Effects of post-deposition heat treatment on the microstructure and properties of Al-doped ZnO thin films prepared by aqueous phase deposition

    Energy Technology Data Exchange (ETDEWEB)

    Yao, Pin-Chuan, E-mail: pcyao@mail.dyu.edu.tw [Department of Materials Science and Engineering, Da-Yeh University, Dacun, Changhua 51591, Taiwan (China); Hang, Shih-Tse; Wu, Menq-Jiun [Department of Mechatronics Engineering, National Changhua University of Education, Changhua 50007, Taiwan (China); Hsiao, Wen-Tse [Instrument Technology Research Center, National Applied Research Laboratories, Hsinchu 30076, Taiwan (China)

    2012-01-31

    which, less porous structures were formed at elevated temperature. - Highlights: Black-Right-Pointing-Pointer Transparent conducting Al-doped ZnO films were prepared by aqueous phase deposition. Black-Right-Pointing-Pointer By a two-step heat treatment, the resistivities of the films declined considerably. Black-Right-Pointing-Pointer Reducing atmosphere is beneficial for the grain sizes and carrier concentrations. Black-Right-Pointing-Pointer The electrical resistivity was declined steadily with heat treatment temperature. Black-Right-Pointing-Pointer Scattering within grains is dominant due to the small mean free path of the carriers.

  11. Comparative studies of Al-doped ZnO and Ga-doped ZnO transparent conducting oxide thin films.

    Science.gov (United States)

    Jun, Min-Chul; Park, Sang-Uk; Koh, Jung-Hyuk

    2012-11-22

    We have investigated the influences of aluminum and gallium dopants (0 to 2.0 mol%) on zinc oxide (ZnO) thin films regarding crystallization and electrical and optical properties for application in transparent conducting oxide devices. Al- and Ga-doped ZnO thin films were deposited on glass substrates (corning 1737) by sol-gel spin-coating process. As a starting material, AlCl3⋅6H2O, Ga(NO3)2, and Zn(CH3COO)2⋅2H2O were used. A lowest sheet resistance of 3.3 × 103 Ω/□ was obtained for the GZO thin film doped with 1.5 mol% of Ga after post-annealing at 650°C for 60 min in air. All the films showed more than 85% transparency in the visible region. We have studied the structural and microstructural properties as a function of Al and Ga concentrations through X-ray diffraction and scanning electron microscopy analysis. In addition, the optical bandgap and photoluminescence were estimated.

  12. Effects of NIR annealing on the characteristics of al-doped ZnO thin films prepared by RF sputtering.

    Science.gov (United States)

    Jun, Min-Chul; Koh, Jung-Hyuk

    2012-06-06

    Aluminum-doped zinc oxide (AZO) thin films have been deposited on glass substrates by employing radio frequency (RF) sputtering method for transparent conducting oxide applications. For the RF sputtering process, a ZnO:Al2O3 (2 wt.%) target was employed. In this paper, the effects of near infrared ray (NIR) annealing technique on the structural, optical, and electrical properties of the AZO thin films have been researched. Experimental results showed that NIR annealing affected the microstructure, electrical resistance, and optical transmittance of the AZO thin films. X-ray diffraction analysis revealed that all films have a hexagonal wurtzite crystal structure with the preferentially c-axis oriented normal to the substrate surface. Optical transmittance spectra of the AZO thin films exhibited transmittance higher than about 80% within the visible wavelength region, and the optical direct bandgap (Eg) of the AZO films was increased with increasing the NIR energy efficiency.

  13. Study of Electrical, Optical and Structural Properties of Al- Doped ZnO Thin Films on PEN Substrates

    Directory of Open Access Journals (Sweden)

    Mohit Agarwal

    2013-05-01

    Full Text Available Aluminum-doped zinc oxide (AZO, as one of the most promising transparent conducting oxide (TCO material, has now been widely used in thin film solar cells. Most of the study of AZO films till date has been done on glass substrates but nowadays there is a growing interest in replacing glass with polymer substrate for the thin-film solar cell technology and many other flexible optoelectronic devices. In this study, AZO thin films were deposited at room temperature by RF magnetron sputtering on flexible substrates from a 3 inch diameter target of 2 wt % Al2O3 in zinc oxide. The effect of RF power on the structural, optical and electrical properties of AZO films was investigated by X-ray Diffraction (XRD, Hall measurement, and UV-visible spectrophotometery. The XRD data indicates a preferential c-axis orientation for all the films. All films exhibit high transmittance ( 85% in visible region. Films deposited at 60 W power exhibit lowest resistivity of 1.2  10 – 3 Ωcm.

  14. Optical and structural properties of Al-doped ZnO thin films by sol gel process.

    Science.gov (United States)

    Jun, Min-Chul; Koh, Jung-Hyuk

    2013-05-01

    Transparent conducting oxide (TCO) materials with high transmittance and good electrical conductivity have been attracted much attention due to the development of electronic display and devices such as organic light emitting diodes (OLEDs), and dye-sensitized solar cells (DSSCs). Aluminum doped zinc oxide thin films (AZO) have been well known for their use as TCO materials due to its stability, cost-effectiveness, good optical transmittance and electrical properties. Especially, AZO thin film, which have low resistivity of 2-4 x 10(-4) omega x cm which is similar to that of ITO films with wide band gap semiconductors. The AZO thin films were deposited on glass substrates by sol-gel spin-coating process. As a starting material, zinc acetate dihydrate (Zn(CH3COO)2 x 2H2O) and aluminum chloride hexahydrate (AlCl3 6H2O) were used. 2-methoxyethanol and monoethanolamine (MEA) were used as solvent and stabilizer, respectively. After deposited, the films were preheated at 300 degrees C on a hotplate and post-heated at 650 degrees C for 1.5 hrs in the furnace. We have studied the structural and optical properties as a function of Al concentration (0-2.5 mol.%).

  15. Compositional study of vacuum annealed Al doped ZnO thin films obtained by RF magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Shantheyanda, B. P.; Todi, V. O.; Sundaram, K. B.; Vijayakumar, A.; Oladeji, I. [Department of Electrical Engineering and Computer Science, University of Central Florida, Orlando, Florida 32816 (United States); Planar Energy Inc., 653 W. Michigan St., Orlando, Florida 32805 (United States)

    2011-09-15

    Aluminum doped zinc oxide (AZO) thin films were obtained by RF magnetron sputtering. The effects of deposition parameters such as power, gas flow conditions, and substrate heating have been studied. Deposited and annealed films were characterized for composition as well as microstructure using x ray photoelectron spectroscopy and x ray diffraction. Films produced were polycrystalline in nature. Surface imaging and roughness studies were carried out using SEM and AFM, respectively. Columnar grain growth was predominantly observed. Optical and electrical properties were evaluated for transparent conducting oxide applications. Processing conditions were optimized to obtain highly transparent AZO films with a low resistivity value of 6.67 x 10{sup -4}{Omega} cm.

  16. Deposition of transparent and conductive Al-doped ZnO thin films for photovoltaic solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Martinez, M.A.; Herrero, J.; Gutierrez, M.T. [Instituto de Energias Renovables CIEMAT, Madrid (Spain)

    1996-01-08

    The effect of the substrate temperature on the optoelectronic properties of ZnO-based thin films prepared by rf magnetron sputtering has been studied. Three different targets (Zn/Al 98/2 at%, ZnO:Al 98/2 at% and ZnO:Al{sub 2}O{sub 3} 98/2 wt%) have been investigated in order to compare resulting samples and try to reduce the substrate temperature down to room temperature. From the ZnO:Al{sub 2}O{sub 3} target, transparent conductive zinc oxide has been obtained at 25C with the average optical transmission in the 400-800 nm wavelength range, T=80-90% and resistivity, {rho}=3-5x10{sup -3} {Omega}cm. In Al:ZnO layers, the spatial distribution of the electrical properties across the substrate placed parallel to the target has been improved by depositing at high substrate temperatures, above 200C. Besides, owing to diffusion processes of CuInSe{sub 2} and CdS take place at 200C, an Al:ZnO/CdS/CuInSe{sub 2} polycrystalline solar cell made with the Al:ZnO deposited at 25C as the transparent conductive oxide, has shown a more efficient photovoltaic response, {eta}=6.8%, than the one measured when the aluminium-doped zinc oxide has been prepared at 200C, {eta}=1.8%

  17. Recombination luminescence and trap levels in undoped and Al-doped ZnO thin films on quartz and GaSe (0 0 0 1) substrates

    Energy Technology Data Exchange (ETDEWEB)

    Evtodiev, I. [Moldova State University, 60 A. Mateevici Str., Chisinau, MD 2009, Republic of Moldova (Moldova, Republic of); Caraman, I. [Vasile Alecsandri University of Bacau, 157 Calea Marasesti, RO 600115 Bacau (Romania); Leontie, L., E-mail: lleontie@uaic.ro [Alexandru Ioan Cuza University of Iasi, Bd. Carol I, Nr. 11, RO 700506 Iasi (Romania); Rusu, D.-I. [Vasile Alecsandri University of Bacau, 157 Calea Marasesti, RO 600115 Bacau (Romania); Dafinei, A. [Faculty of Physics, University of Bucharest, Platforma Magurele, Str. Fizicienilor nr. 1, CP Mg - 11, Bucharest-Magurele, RO 76900 (Romania); Nedeff, V.; Lazar, G. [Vasile Alecsandri University of Bacau, 157 Calea Marasesti, RO 600115 Bacau (Romania)

    2012-03-15

    Highlights: Black-Right-Pointing-Pointer ZnO films on GaSe create electron trapping states and PL recombination levels. Black-Right-Pointing-Pointer Zn and Al diffusion in GaSe produces low-energy widening of its PL emission. Black-Right-Pointing-Pointer ZnO:Al films on GaSe lamellas are suitable for gas-discharge lamp applications. -- Abstract: Photoluminescence spectra of ZnO and ZnO:Al (1.00, 2.00 and 5.00 at.%) films on GaSe (0 0 0 1) lamellas and amorphous quartz substrates, obtained by annealing, at 700 K, of undoped and Al-doped metal films, are investigated. For all samples, the nonequilibrium charge carriers recombine by radiative band-to-band transitions with energy of 3.27 eV, via recombination levels created by the monoionized oxygen atoms, forming the impurity band laying in the region 2.00 - 2.70 eV. Al doping induces an additional recombination level at 1.13 eV above the top of the valence band of ZnO films on GaSe substrates. As a result of thermal diffusion of Zn and Al into the GaSe interface layer from ZnO:Al/GaSe heterojunction, electron trap levels located at 0.22 eV and 0.26 eV below the conduction band edge of GaSe, as well as a deep recombination level, responsible for the luminescent emission in the region 1.10 - 1.40 eV, are created.

  18. Controlling the surface nanostructure of ZnO and Al-doped ZnO thin films using electrostatic spraying for their application in 12% efficient perovskite solar cells.

    Science.gov (United States)

    Mahmood, Khalid; Swain, Bhabani Sankar; Jung, Hyun Suk

    2014-08-07

    In this paper, ZnO and Al-doped ZnO films were deposited using the electrospraying method and studied for the first time as photoanodes for efficient perovskite solar cells. Effects of substrate temperature, deposition time, applied voltage, substrate-to-nozzle distance and flow rate (droplet size) on the morphology of ZnO were studied with the help of FE-SEM images. The major factors such as the droplet size of the spray, substrate temperature and substrate-to-nozzle distance at deposition control the film morphology. Indeed, these factors determine the density of the film, its smoothness and the flow of solution over the substrate. The droplet size was controlled by the flow rate of the spray. The substrate-to-nozzle distance and flow rate will both regulate the solution amount deposited on the surface of the substrate. The most favorable conditions for a good quality ZnO thin film were a long substrate-to-nozzle distance and lower solution flow rates. In situ droplet size measurement shows that the size and dispersion of particles were narrowed. The method was shown to have a high deposition rate and efficiency relative to well-established thin film deposition techniques such as chemical and physical vapor deposition. In addition, it also allows easy control of the microstructure and stoichiometry of the deposits. The pure ZnO film produced under optimum conditions (440 nm thick) demonstrated a high power conversion efficiency (PCE) of 10.8% when used as a photoanode for perovskite solar cells, owing to its high porosity, uniform morphology and efficient electron transport. For thicker films a drastic decrease in PCE was observed due to their low porosity. We also observed that the open-circuit voltage increases from 1010 mV to 1045 mV and also the PCE increases from 10.8% to 12.0% when pure ZnO films were doped with aluminum (Al). Under atmospheric pressure, the electrospraying system produces the reasonably uniform-sized droplets of smaller size, so the films

  19. Study on the structure and morphology of Er/Yb/Al-doped ZnO thin film%Er/Yb/Al掺杂ZnO薄膜的结构与形貌研究

    Institute of Scientific and Technical Information of China (English)

    韩利新; 张宁玉; 霍庆松; 宋红莲

    2011-01-01

    ZnO thin films and Er/Yb/Al-doped ZnO thin films on Si substrate were fabricated by using RF magnetron sputtering method at room temperature. The XRD structure analysis shows that undoped ZnO thin film grows along the C orientation, but doped ZnO thin films deviate from the normal growth orientation and become nano-multi-crystal structure which is along (102) orientation and the crystal-lite size of ZnO thin film doped the Er/Yb /Al decreases with the increase of the content of the Er ele-ment. The morphology by AFM analysis shows that Er3 + 、Yb3 +、Al3+ that is doped in the ZnO thin films cause a change of crystal field and make the surface roughness larger.%采用射频磁控溅射技术在室温下Si衬底上制备了ZnO薄膜和Er/Yb/Al掺杂的ZnO薄膜.通过对XRD的结构分析表明:未掺杂ZnO薄膜沿c取向性生长,掺杂ZnO薄膜偏离了正常生长,变为(102)取向性生长的纳米多晶结构;Er/Yb/Al掺杂的ZnO薄膜的晶粒尺寸随着Er元素含量的增多而减小.经AFM对其形貌分析表明:Er3+、yb3+、Al3+的掺入引起了ZnO薄膜晶格场变化,使薄膜表面粗糙度变大.

  20. Effects of deposition temperatures and annealing conditions on the microstructural, electrical and optical properties of polycrystalline Al-doped ZnO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Oh, Joon-Ho [Department of Materials Science and Engineering, Korea University, Seoul 136-713 (Korea, Republic of); Kim, Kyoung-Kook [Department of Nano-Optical Engineering, Korea Polytechnic University, Gyeonggi 429-793 (Korea, Republic of); Seong, Tae-Yeon, E-mail: tyseong@korea.ac.kr [Department of Materials Science and Engineering, Korea University, Seoul 136-713 (Korea, Republic of)

    2011-01-15

    Al-doped ZnO (AZO, ZnO:Al{sub 2}O{sub 3} = 98:2 wt%) films are deposited on different substrates by an RF magnetron sputtering and subsequently annealed at three different conditions to investigate the microstructural, electrical, and optical properties. X-ray diffraction and scanning electron microscope results show that all the samples are polycrystalline and the samples rapid-thermal-annealed at 900 deg. C in an N{sub 2} ambient contain larger grains compared to the furnace-annealed samples. It is shown that the sample deposited at room temperature on the sapphire gives a resistivity of 5.57 x 10{sup -4} {Omega} cm when furnace-annealed at 500 deg. C in a mixture of N{sub 2}:H{sub 2} (9:1). It is also shown that the Hall mobility vs. carrier concentration ({mu}-n) relation is divided into two groups, depending on the annealing conditions, namely, either rapid-thermal annealing or furnace annealing. The relations are described in terms of either grain boundary scattering or ionized impurity scattering mechanism. In addition, the samples produce fairly high transmittance of 91-96.99% across the wavelength region of 400-1100 nm. The optical bandgaps of the samples increase with increasing carrier concentration.

  1. Defects generated by MF magnetron sputtering and their influences on the electrical and optical properties of Al doped ZnO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Hao, Changshan; Shirolkar, Mandar M.; Li, Jieni [Hefei National Laboratory for Physical Science at the Microscale, University of Science and Technology of China, Hefei, Anhui 230026 (China); Wu, Binjun [Hefei National Laboratory for Physical Science at the Microscale, University of Science and Technology of China, Hefei, Anhui 230026 (China); QinZhou College, QinZhou, Guangxi 535000 (China); Yin, Shiliu; Li, Ming [Hefei National Laboratory for Physical Science at the Microscale, University of Science and Technology of China, Hefei, Anhui 230026 (China); Wang, Haiqian, E-mail: hqwang@ustc.edu.cn [Hefei National Laboratory for Physical Science at the Microscale, University of Science and Technology of China, Hefei, Anhui 230026 (China)

    2015-10-01

    Highlights: • Oxygen interstitial dominates the carrier concentration of sputtered films. • Chemisorbed oxygen decreases the mobility of sputtered films. • Hydrogen annealing can remove oxygen interstitials and chemisorbed oxygen. • High and low resistivity states (HRS and LRS) are observed under hydrogen atmosphere. • Defect configurations of (H{sub 2}){sub i} and H{sub O} + H{sub i} are assigned to HRS and LRS. - Abstract: In this paper, the defects of Al doped ZnO films generated by magnetron sputtering in the deposition processes are comprehensively investigated. It is found that oxygen ion bombardment deteriorates the crystallinity and generates oxygen related defects, such as oxygen interstitials (O{sub i}), chemisorbed oxygen at the grain boundaries (O{sub GB}), and oxygen vacancies (V{sub O}). O{sub i} and O{sub GB} decrease the carrier concentration and mobility of the pristine films remarkably, but they can be removed by hydrogen annealing. However, the grain boundary scattering originated from poor crystallinity cannot be reduced by the annealing below 450 °C. Moreover, the in-situ temperature-dependent resistivity measurement under hydrogen atmosphere suggests that hydrogen atoms are incorporated into the ZnO: Al films and interact with V{sub O}. We propose that there are two energetically favorable states for the incorporated hydrogen. The defect configurations of (H{sub 2}){sub i} and H{sub O} + H{sub i} are assigned to the high resistivity state (HRS) and low resistivity state (LRS) respectively and the switching between these two states is activated by V{sub O} and mediated by a metastable state (H{sub 2}){sup *}{sub O}. The transformation between these two resistivity states leads to a hysteresis loop during the heating and cooling process.

  2. The effect of dopant concentration on properties of transparent conducting Al-doped ZnO thin films for efficient Cu2ZnSnS4 thin-film solar cells prepared by electrodeposition method

    Science.gov (United States)

    Mkawi, E. M.; Ibrahim, K.; Ali, M. K. M.; Farrukh, M. A.; Mohamed, A. S.

    2015-11-01

    Al-doped ZnO (AZO) thin films were potentiostatically deposited on indium tin oxide substrates. The influence of the doping level of the ZnO:Al films was investigated. The results of the X-ray diffraction and scanning electron microscopy analysis revealed that the structural properties of the AZO films were found polycrystalline with a hexagonal wurtzite-type structure along the (002) plane. The grain size of the AZO films was observed as approximately 3 μm in the film doping with 4 mol% ZnO:Al concentration. The thin films also exhibited an optical transmittance as high as 90 % in the wavelength range of 100-1,000 nm. The optical band gap increased from 3.33 to 3.45 eV. Based on the Hall studies, the lowest resistivity (4.78 × 10-3 Ω cm) was observed in the film doping with 3 mol% ZnO:Al concentration. The sheet resistant, carrier concentration and Hall mobility values were found as 10.78 Ω/ square, 9.03 × 1018 cm-3 and 22.01 cm2/v s, respectively, which showed improvements in the properties of AZO thin films. The ZnO:Al thin films were used as a buffer layer in thin-film solar cells with the structure of soda-lime glass/Mo/Cu2ZnSnS4/ZnS/ZnO/Al grid. The best solar cell efficiency was 2.3 % with V OC of 0.430 V, J SC of 8.24 mA cm-2 and FF of 68.1 %.

  3. Effect of oxygen to argon flow ratio on the properties of Al-doped ZnO films for amorphous silicon thin film solar cell applications

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Yang-Shih [Department of Materials Science and Engineering, National Chung Hsing University, Taichung 402, Taiwan, ROC (China); Lien, Shui-Yang, E-mail: syl@mdu.edu.tw [Department of Materials Science and Engineering, MingDao University, ChangHua 52345, Taiwan, ROC (China); Huang, Yung-Chuan [Department of Materials Science and Engineering, MingDao University, ChangHua 52345, Taiwan, ROC (China); Wang, Chao-Chun [Department of Materials Science and Engineering, National Chung Hsing University, Taichung 402, Taiwan, ROC (China); Liu, Chueh-Yang [Department of Materials Science and Engineering, MingDao University, ChangHua 52345, Taiwan, ROC (China); Nautiyal, Asheesh [Department of Mechanical Engineering, Yuan Ze University, 135 Yuan-Tung Road, Chungli, 320 Taoyuan, Taiwan, ROC (China); Wuu, Dong-Sing [Department of Materials Science and Engineering, National Chung Hsing University, Taichung 402, Taiwan, ROC (China); Lee, Shuo-Jun [Department of Mechanical Engineering, Yuan Ze University, 135 Yuan-Tung Road, Chungli, 320 Taoyuan, Taiwan, ROC (China)

    2013-02-01

    Transparent conductive oxide thin films in solar cell fabrication have attracted much attention due to their high conductivity and transmittance. In this paper, we have investigated the aluminum-doped zinc oxide (AZO) thin films prepared by radiofrequency magnetron sputtering on Asahi U-type SnO{sub 2} glass with different O{sub 2}/Ar flow ratios in vacuum chamber. Furthermore, the micro-structural, electrical, and optical properties of AZO/SnO{sub 2} films were studied. The change in O{sub 2}/Ar flow ratios is found to significantly affect the haze value, and slightly affect electrical resistivity and transmittance of the films. Afterward, the fabricated AZO thin films with different O{sub 2}/Ar flow ratios were used for building the solar cell devices. The current–voltage and external quantum efficiency characteristics were investigated for the solar cell devices. The optimized O{sub 2}/Ar flow ratio of 3 for solar device shows the best efficiency of 10.41%, and a 20% increase in short-circuit current density compared to typical Asahi solar cells. - Highlights: ► A thin Al-doped zinc oxide (AZO) film has been deposited on SnO{sub 2} substrates. ► The AZO film deposited at an O{sub 2}/Ar ratio of 3 shows low resistivity and high haze. ► The AZO film contains tiny grains that enhance light scattering. ► The amorphous silicon solar cell with the AZO layer shows a 20% increase in Jsc.

  4. Effect of sputtering power on crystallinity, intrinsic defects, and optical and electrical properties of Al-doped ZnO transparent conducting thin films for optoelectronic devices

    Science.gov (United States)

    Hu, Yu Min; Li, Jung Yu; Chen, Nai Yun; Chen, Chih Yu; Han, Tai Chun; Yu, Chin Chung

    2017-02-01

    The crystallinity and intrinsic defects of transparent conducting oxide (TCO) films have a high impact on their optical and electrical properties and therefore on the performance of devices incorporating such films, including flat panel displays, electro-optical devices, and solar cells. The optical and electrical properties of TCO films can be modified by tailoring their deposition parameters, which makes proper understanding of these parameters crucial. Magnetron sputtering is the most adaptable method for preparing TCO films used in industrial applications. In this study, we investigate the direct and inter-property correlation effects of sputtering power (PW) on the crystallinity, intrinsic defects, and optical and electrical properties of Al-doped ZnO (AZO) TCO films. All of the films were preferentially c-axis-oriented with a wurtzite structure and had an average transmittance of over 80% in the visible wavelength region. Scanning electron microscopy images revealed significantly increased AZO film grain sizes for PW ≥ 150 W, which may lead to increased conductivity, carrier concentration, and optical band gaps but decreased carrier mobility and in-plane compressive stress in AZO films. Photoluminescence results showed that, with increasing PW, the near band edge emission gradually dominates the defect-related emissions in which zinc interstitial (Zni), oxygen vacancy (VO), and oxygen interstitial (Oi) are possibly responsible for emissions at 3.08, 2.8, and 2.0 eV, respectively. The presence of Zni- and Oi-related emissions at PW ≥ 150 W indicates a slight increase in the presence of Al atoms substituted at Zn sites (AlZn). The presence of Oi at PW ≥ 150 W was also confirmed by X-ray photoelectron spectroscopy results. These results clearly show that the crystallinity and intrinsic-defect type of AZO films, which dominate their optical and electrical properties, may be controlled by PW. This understanding may facilitate the development of TCO

  5. Hydrothermal growth and properties of rod-like ZnO submicron crystals on Al-doped ZnO seed layers with different Al concentrations

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Do Yeob; Kim, Sung O [Clemson University, Clemson, South Carolina (United States); Kim, Min Su; Yim, Kwang Gug; Leem, Jae Young; Kim, Soa Ram; Nam, Gi Woong [Inje University, Gimhae (Korea, Republic of); Lee, Dong Yul [Samsung LED Co. Ltd., Suwon (Korea, Republic of)

    2012-01-15

    The authors used a sol-gel method to deposit Al-doped ZnO (AZO) thin films on Si substrates and a hydrothermal method to grow ZnO crystals on the as-prepared AZO seed layers. Though the crystallinity of the seed layers was enhanced by Al doping, for Al doping up to 3 at.%, the full width at half maximum (FWHM) of the ZnO (002) diffraction peak increased, resulting in a decrease in the average grain size. The intensity of the ZnO (002) diffraction peak of ZnO crystals grown on AZO seed layers increased as the Al doping concentration was increased to 1.0 at.%. The narrowest FWHM in the photoluminescence spectrum, 132 meV was obtained at an Al doping concentration of 1.0 at.%. These results indicate that the structural and the optical properties of ZnO crystals grown on seed layers can be enhanced by introducing a small amount of an Al dopant into the seed layers.

  6. Characteristics of Al-doped ZnO thin films prepared in Ar + H{sub 2} atmosphere and their vacuum annealing behavior

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Bailin; Lü, Kun; Wang, Jun; Li, Taotao; Wu, Jun [Key Laboratory for Ferrous Metallurgy and Resources Utilization of Ministry of Education, Wuhan University of Science and Technology, Wuhan 430081 (China); Zeng, Dawen; Xie, Changsheng [Department of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China)

    2013-11-15

    The microstructure and electrical–optical properties of Al-doped ZnO (AZO) films have been studied as a function of H{sub 2} flux in the magnetron sputtering process at 150 °C and postannealing temperature in vacuum. As H{sub 2} flux increases in the sputtering gas, the AZO films deposited have a (002) preferred orientation rather than the mixed (100) and (002) orientations, the grain size shows a tendency to first increase then decrease, and (002) diffraction peak position is inclined to shift to higher angles first then to lower angles. The resistivity of the films first decreases then increases with H{sub 2} flux, and the lowest resistivity of 4.02 × 10{sup −4}Ω cm is obtained at a H{sub 2} flux of 10 sccm. The average transmittance in the visible region shows little dependence on H{sub 2} flux. As a whole, the AZO films with higher values of figure of merit are obtained when the H{sub 2} flux is in the range of 6–12 sccm. The AZO films deposited in Ar and Ar + H{sub 2} exhibit different annealing behaviors. For the AZO film deposited in Ar, the grain size gradually increases, the stresses are relaxed, the resistivity first decreases then increases, and the average transmittance in the visible region is unchanged initially then somewhat decreased as annealing temperature is increased. The optimum annealing temperature for improving properties of AZO films deposited in Ar is 300 °C. For the AZO films deposited in Ar + H{sub 2}, annealing does not significantly change the microstructure but increases the resistivity of the films; the average transmittance in the visible region remains unchanged initially but greatly reduced with further increase in annealing temperature. The carrier transport in the as-deposited and annealed films appears to be controlled by a mechanism of grain boundary scattering, and the value of E{sub g} increases with the increase in carrier concentration due to Burstein–Moss effect.

  7. Effect of internal stress on the electro-optical behaviour of Al-doped ZnO transparent conductive thin films

    Science.gov (United States)

    Proost, J.; Henry, F.; Tuyaerts, R.; Michotte, S.

    2016-08-01

    In this work, we will report on scientific efforts aimed at unraveling the quantitative effect of elastic strain on the electro-optical behaviour of Al-doped zinc oxide (AZO). AZO thin films have been deposited by reactive magnetron sputtering to thicknesses from 300 to 500 nm, both on extra-clear glass substrates as well as on oxidised Si wafers. This resulted in both cases in polycrystalline, strongly textured (002) films. During deposition, the internal stress evolution in the growing film was monitored in-situ using high resolution curvature measurements. The resulting growth-induced elastic strain, which was found to depend heavily on the oxygen partial pressure, could further be modulated by appropriately choosing the deposition temperature. The latter also induces an additional extrinsic thermal stress component, whose sign depends on the substrate used. As such, a wide range of biaxial internal stresses could be achieved, from -600 MPa in compression up to 800 MPa in tension. The resulting charge carrier mobilities, obtained independently from room temperature Hall measurements, were found to range between 5 and 25 cm2/V s. Interestingly, the maximum mobility occurred at the zero-stress condition, and together with a charge carrier concentration of about 8 × 1020 cm-3, this gave rise to a resistivity of only 300 μΩ cm. From the stress-dependent optical transmission spectra in the range of 200-1000 nm, the pressure coefficient of the optical bandgap was estimated from the corresponding Tauc plots to be 31 meV/GPa, indicating a very high strain-sensitivity as well.

  8. Significant Enhancement in the Conductivity of Al-Doped Zinc Oxide thin Films for TCO Application

    Science.gov (United States)

    Mohite, R. M.; Ansari, J. N.; Roy, A. S.; Kothawale, R. R.

    2016-03-01

    Nanostructured Al-doped Zinc oxide (ZnO) thin films were deposited on glass substrate by chemical bath deposition (CBD) using aqueous zinc nitrate solution and subjected for different characterizations. Effect of Al3+ substitution on the properties of ZnO annealed at 400∘C was studied by XRD and UV-Vis for structural studies, SEM and TEM for surface morphology and DC four probe resistivity measurements for electrical properties. Al3+ substitution does not influence the morphology and well-known peaks related to wurtzite structure of ZnO. Electron microscopy (SEM and TEM) confirms rod shaped Al-doped ZnO nanocrystals with average width of 50nm. The optical band gap determined by UV-Visible spectroscopy was found to be in the range 3.37eV to 3.44eV. An EPR spectrum of AZO reveals peak at g=1.96 is due to shallow donors Zn interstitial. The DC electrical resistivity measurements of Al-doped ZnO show a minimum resistivity of 3.77×10-2Ω-cm. Therefore, these samples have potential use in n-type window layer in optoelectronic devices, organic solar cells, photonic crystals, photo-detectors, light emitting diodes (LEDs), gas sensors and chemical sensors.

  9. Microstructure, optical and electrical properties of Al-doped ZnO films grown by MOCVD

    Energy Technology Data Exchange (ETDEWEB)

    Su, Jianfeng, E-mail: sujianfengvy@gmail.com [Department of Mathematics and Physics, Luoyang Institute of Science and Technology, Luoyang 471023 (China); Tang, Chunjuan; Niu, Qiang; Zang, Chunhe; Zhang, Yongsheng [Department of Mathematics and Physics, Luoyang Institute of Science and Technology, Luoyang 471023 (China); Fu, Zhuxi [Department of Physics, University of Science and Technology of China, Hefei 230026 (China)

    2012-09-01

    Highlights: Black-Right-Pointing-Pointer Al-doped ZnO films were grown on quartz substrates by MOCVD. Black-Right-Pointing-Pointer The preferred orientation of ZnO films decreased with the increase of Al content. Black-Right-Pointing-Pointer Decomposition products of TMA bringing down the surface activity of ZnO grains. Black-Right-Pointing-Pointer UV emission peak initially red-shifted and then blue-shifted as increasing Al content. Black-Right-Pointing-Pointer Low electrical resistivity of Al-doped ZnO films was obtained. - Abstract: Al-doped ZnO films were grown on quartz substrates by MOCVD. A systematical and detailed study about the effect of Al content on structural, optical and electrical properties were discussed. XRD measurements revealed that the preferred orientation of ZnO films decreased with the increase of Al content. AFM images indicated that the TMA molecules or their decomposition products bringing down the surface activity of ZnO grains, and so grain growth is inhibited. By the band tail states and the quantum confinement effect, the UV emission peak initially red-shifted and then blue-shifted. All Al-doped samples demonstrated more than 80% of the optical transparency in the visible region. Low electrical resistivity of Al-doped ZnO films was obtained. However, due to defects and grain boundary scattering which caused by Al doping, the hall mobility is increased initially and then decreased.

  10. Mediator-free interaction of glucose oxidase, as model enzyme for immobilization, with Al-doped and undoped ZnO thin films laser-deposited on polycarbonate supports.

    Science.gov (United States)

    V T K P, Fidal; Inguva, Saikumar; Krishnamurthy, Satheesh; Marsili, Enrico; Mosnier, Jean-Paul; T S, Chandra

    2017-01-01

    Al doped and undoped ZnO thin films were deposited by pulsed-laser deposition on polycarbonate sheets. The films were characterized by optical transmission, Hall effect measurement, XRD and SEM. Optical transmission and surface reflectometry studies showed good transparency with thicknesses ∼100nm and surface roughness of 10nm. Hall effect measurements showed that the sheet carrier concentration was -1.44×10(15)cm(-2) for AZO and -6×10(14)cm(-2) for ZnO. The films were then modified by drop-casting glucose oxidase (GOx) without the use of any mediators. Higher protein concentration was observed on ZnO as compared to AZO with higher specific activity for ZnO (0.042Umg(-1)) compared to AZO (0.032Umg(-1)), and was in agreement with cyclic voltemmetry (CV). X-ray photoelectron spectroscopy (XPS) suggested that the protein was bound by dipole interactions between AZO lattice oxygen and the amino group of the enzyme. Chronoamperometry showed sensitivity of 5.5μAmM(-1)cm(-2) towards glucose for GOx/AZO and 2.2μAmM(-1)cm(-2) for GOx/ZnO. The limit of detection (LoD) was 167μM of glucose for GOx/AZO, as compared to 360μM for GOx/ZnO. The linearity was 0.28-28mM for GOx/AZO whereas it was 0.6-28mM for GOx/ZnO with a response time of 10s. Possibly due to higher enzyme loading, the decrease of impedance in presence of glucose was larger for GOx/ZnO as compared to GOx/AZO in electrochemical impedance spectroscopy (EIS). Analyses with clinical blood serum samples showed that the systems had good reproducibility and accuracy. The characteristics of novel ZnO and AZO thin films with GOx as a model enzyme, should prove useful for the future fabrication of inexpensive, highly sensitive, disposable electrochemical biosensors for high throughput diagnostics.

  11. Investigations on the roles of position controlled Al layers incorporated into an Al-doped ZnO active channel during atomic layer deposition for thin film transistor applications

    Science.gov (United States)

    Kim, Eom-Ji; Lee, Won-Ho; Yoon, Sung-Min

    2016-03-01

    We investigated the effects of the distance between incorporated Al layers on the characteristics of thin-film transistors (TFTs) using Al-doped ZnO (AZO) as the active channels. The intervals between the Al layers were controlled by designing the sequences of Al cycles during the atomic-layer deposition. Two configurations were designed as “scatter” or “focus”, in which the incorporated Al layers were dispersed to bottom and top sides or concentrated on the center region. Electrical conductivities of “scatter” and “focus” films were observed to be different. While the dispersed Al layers could work as dopants, a too-close interval between the Al layers suppressed carrier transport, even with the same incorporated Al amounts. These differences were reflected on the device characteristics. The TFT performance of the “scatter” device was better than that of the “focus” device. Consequently, adequately dispersed Al layers in the AZO channel are very important for improving device performance.

  12. Temperature dependent dual hydrogen sensor response of Pd nanoparticle decorated Al doped ZnO surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, D.; Barman, P. B.; Hazra, S. K., E-mail: surajithazra@yahoo.co.in [Department of Physics and Materials Science, Jaypee University of Information Technology, Waknaghat, Solan, Himachal Pradesh-173234 (India); Dutta, D. [IC Design and Fabrication Centre, Department of Electronics and Telecommunication Engineering, Jadavpur University, Kolkata-700032 (India); Kumar, M.; Som, T. [SUNAG Laboratory, Institute of Physics, Sachivalaya Marg, Bhubaneswar 751005 (India)

    2015-10-28

    Sputter deposited Al doped ZnO (AZO) thin films exhibit a dual hydrogen sensing response in the temperature range 40 °C–150 °C after surface modifications with palladium nanoparticles. The unmodified AZO films showed no response in hydrogen in the temperature range 40 °C–150 °C. The operational temperature windows on the low and high temperature sides have been estimated by isolating the semiconductor-to-metal transition temperature zone of the sensor device. The gas response pattern was modeled by considering various adsorption isotherms, which revealed the dominance of heterogeneous adsorption characteristics. The Arrhenius adsorption barrier showed dual variation with change in hydrogen gas concentration on either side of the semiconductor-to-metal transition. A detailed analysis of the hydrogen gas response pattern by considering the changes in nano palladium due to hydrogen adsorption, and semiconductor-to-metal transition of nanocrystalline Al doped ZnO layer due to temperature, along with material characterization studies by glancing incidence X-ray diffraction, atomic force microscopy, and transmission electron microscopy, are presented.

  13. Effect of thickness on structural and electrical properties of Al-doped ZnO films

    Energy Technology Data Exchange (ETDEWEB)

    Garcés, F.A., E-mail: felipe.garces@santafe-conicet.gov.ar [Instituto de Física del Litoral (CONICET-UNL), Güemes 3450, Santa Fe S3000GLN (Argentina); Budini, N. [Instituto de Física del Litoral (CONICET-UNL), Güemes 3450, Santa Fe S3000GLN (Argentina); Arce, R.D.; Schmidt, J.A. [Instituto de Física del Litoral (CONICET-UNL), Güemes 3450, Santa Fe S3000GLN (Argentina); Facultad de Ingeniería Química, Universidad Nacional del Litoral, Santiago del Estero 2829, Santa Fe S3000AOM (Argentina)

    2015-01-01

    In this work, we have investigated the influence of thickness on structural and electrical properties of Al-doped ZnO films. Transparent conducting oxide films were grown by the spray pyrolysis technique from precursors prepared via the sol–gel method. We determined the structural properties of the films by performing X-ray diffraction and mosaicity measurements, which evidenced an increase of disorder and inhomogeneity between crystalline domains as the films thickened. This behavior was contrasted with results obtained from electrical measurements and was attributed to plastic deformation of the films as their thickness increased. As a result, the carrier mobility, the optical gap and the activation energy are affected due to emerging grain boundaries and a higher degree of disorder. - Highlights: • Al-doped ZnO thin films on glass with different thicknesses • Film thickness affects the morphological and electrical properties. • Increasing time deposition allows modification of resistivity and Hall mobility. • Mosaicity between crystalline domains increases with film thickness.

  14. Electrodeposition of Al-doped ZnO nanoflowers with enhanced photocatalytic performance.

    Science.gov (United States)

    She, Guangwei; Chen, Xue; Wang, Yao; Qi, Xiaopeng; Mu, Lixuan; Shi, Wensheng

    2012-03-01

    In this study, Al-doped ZnO nanoflowers were fabricated on conductive substrates via a simple electrodeposition process. The Al-doped ZnO nanoflowers are three-dimensional micro/nano hierarchical structures composed of numerous nanosheets. The chemical composition and crystal structure of the as-synthesized nanoflowers were characterized by EDS, XPS, XRD and HRTEM. It was found that the Al doping led to the decrease of the band gap of ZnO from 3.21 eV to 3.07 eV. Considering the large surface areas, the Al-doped ZnO nanoflowers were used as the photocatalyst for degradation of methyl orange, and exhibited a significantly enhanced performance comparing with the undoped ZnO nanostructures. The good photocatalytic performance should be related to the large surface areas of the nanoflowers and the more free carriers in the Al-doped ZnO, which are introduced by the dopants.

  15. Growth of arrays of Al-doped ZnO nanocones by pulsed laser deposition.

    Science.gov (United States)

    Sun, Ye; Addison, Katherine E; Ashfold, Michael N R

    2007-12-12

    Arrays of aligned Al-doped ZnO nanocones have been synthesized by pulsed laser deposition following excimer laser ablation of a ceramic ZnO target containing 2% Al(2)O(3) (by weight). The elemental composition, microstructural and optical properties of the products were examined by laser induced breakdown spectroscopy, electron microscopy, x-ray diffraction and room temperature photoluminescence measurements. The incident laser fluence was identified as a key parameter in nanocone formation. Their tapered morphologies and small tip diameters (approximately 5 nm) suggest that Al-doped ZnO nanocones could find application as field emitters and as a gas sensing material.

  16. Al-Doped ZnO Monolayer as a Promising Transparent Electrode Material: A First-Principles Study

    Directory of Open Access Journals (Sweden)

    Mingyang Wu

    2017-03-01

    Full Text Available Al-doped ZnO has attracted much attention as a transparent electrode. The graphene-like ZnO monolayer as a two-dimensional nanostructure material shows exceptional properties compared to bulk ZnO. Here, through first-principle calculations, we found that the transparency in the visible light region of Al-doped ZnO monolayer is significantly enhanced compared to the bulk counterpart. In particular, the 12.5 at% Al-doped ZnO monolayer exhibits the highest visible transmittance of above 99%. Further, the electrical conductivity of the ZnO monolayer is enhanced as a result of Al doping, which also occurred in the bulk system. Our results suggest that Al-doped ZnO monolayer is a promising transparent conducting electrode for nanoscale optoelectronic device applications.

  17. Al-Doped ZnO Monolayer as a Promising Transparent Electrode Material: A First-Principles Study.

    Science.gov (United States)

    Wu, Mingyang; Sun, Dan; Tan, Changlong; Tian, Xiaohua; Huang, Yuewu

    2017-03-29

    Al-doped ZnO has attracted much attention as a transparent electrode. The graphene-like ZnO monolayer as a two-dimensional nanostructure material shows exceptional properties compared to bulk ZnO. Here, through first-principle calculations, we found that the transparency in the visible light region of Al-doped ZnO monolayer is significantly enhanced compared to the bulk counterpart. In particular, the 12.5 at% Al-doped ZnO monolayer exhibits the highest visible transmittance of above 99%. Further, the electrical conductivity of the ZnO monolayer is enhanced as a result of Al doping, which also occurred in the bulk system. Our results suggest that Al-doped ZnO monolayer is a promising transparent conducting electrode for nanoscale optoelectronic device applications.

  18. Conformal Al doped ZnO on rough silicon surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Otto, Martin; Miclea, Paul T. [Martin-Luther-University Halle-Wittenberg, Institute of Physics, Heinrich Damerow Str. 4, 06120 Halle (Germany); Kroll, Matthias; Kaesebier, Thomas [Friedrich-Schiller-University Jena, Institute for Applied Physics, Max-Wien-Platz 1, 07743 Jena (Germany); Salzer, Roland [Fraunhofer Institute for Mechanics of Materials Halle IWM, Walter-Huelse-Str.1, 06120 Halle (Germany); Wehrspohn, Ralf B. [Martin-Luther-University Halle-Wittenberg, Institute of Physics, Heinrich Damerow Str. 4, 06120 Halle (Germany); Fraunhofer Institute for Mechanics of Materials Halle IWM, Walter-Huelse-Str.1, 06120 Halle (Germany)

    2011-07-01

    The feasibility of perfectly conformal deposition of transparent but highly conductive ZnO thin films on rough silicon surfaces for photovoltaic applications has been investigated. Aluminum doped zinc oxide (AZO) deposited via thermal ALD was used as a conformal cover layer for plasma etched black silicon. The coated structures achieve reflectances as low as 2.5% throughout the whole visible spectrum whereas the films exhibit resistivities of only 1.1.10{sup -3} {omega}cm. An absorption enhancement of nearly a factor of 10 at a wavelength of 1150 nm compared to a simulated perfect ARC was observed.

  19. Structure-dependent optical and electrical transport properties of nanostructured Al-doped ZnO.

    Science.gov (United States)

    Gondoni, P; Ghidelli, M; Di Fonzo, F; Carminati, M; Russo, V; Li Bassi, A; Casari, C S

    2012-09-14

    The structure-property relation of nanostructured Al-doped ZnO thin films has been investigated in detail through a systematic variation of structure and morphology, with particular emphasis on how they affect optical and electrical properties. A variety of structures, ranging from compact polycrystalline films to mesoporous, hierarchically organized cluster assemblies, are grown by pulsed laser deposition at room temperature at different oxygen pressures. We investigate the dependence of functional properties on structure and morphology and show how the correlation between electrical and optical properties can be studied to evaluate energy gap, conduction band effective mass and transport mechanisms. Understanding these properties opens up opportunities for specific applications in photovoltaic devices, where optimized combinations of conductivity, transparency and light scattering are required.

  20. Preparation of Al-doped ZnO nanocrystalline aggregates with enhanced performance for dye adsorption

    Science.gov (United States)

    Zhang, Jin; Que, WenXiu; Yuan, Yuan; Zhong, Peng; Liao, YuLong

    2012-07-01

    Al-doped ZnO (AZO) nanocrystalline aggregates (NCAs) were prepared by a low cost colloid chemistry method and effects of the Al-doped concentration on the morphological and structural properties of the AZO NCAs were studied. The dye adsorption ability of the AZO NCAs with various Al-doped concentrations was also investigated. Results indicate that the doping of the Al ions not only does not change the wurtzite structure of the ZnO crystal but also can reduce the crystallite grain size and the particle size distribution of the NCAs, which gives them a higher specific surface area and dye adsorption ability than that of the ZnO NCAs. The as-prepared AZO NCAs would be a promising material to be applied in the dye sensitized solar cells and water treatment.

  1. Gas sensing properties of Al-doped ZnO for UV-activated CO detection

    Science.gov (United States)

    Dhahri, R.; Hjiri, M.; El Mir, L.; Bonavita, A.; Iannazzo, D.; Latino, M.; Donato, N.; Leonardi, S. G.; Neri, G.

    2016-04-01

    Al-doped ZnO (AZO) samples were prepared using a modified sol-gel route and charaterized by means of trasmission electron microscopy, x-ray diffraction and photoluminescence analysis. Resistive planar devices based on thick films of AZO deposited on interdigitated alumina substrates were fabricated and investigated as UV light activated CO sensors. CO sensing tests were performed in both dark and illumination condition by exposing the samples to UV radiation (λ  =  400 nm).Under UV light, Al-doped ZnO gas sensors operated at lower temperature than in dark. Furthermore, by photoactivation we also promoted CO sensitivity and made signal recovery of AZO sensors faster. Results demonstrate that Al-doped ZnO might be a promising sensing material for the detection of CO under UV illumination.

  2. Fabrication of Al-Doped ZnO Film with High Conductivity Induced by Photocatalytic Activity

    Science.gov (United States)

    Hong, Jeongsoo; Katsumata, Ken-ichi; Matsushita, Nobuhiro

    2016-10-01

    We have fabricated Al-doped ZnO films by a spin-spray method, achieving high conductivity by Al-ion doping and photocatalytic activity of the ZnO. The surface morphology of the as-deposited films was varied by changing the Al concentration and addition of citrate ions. As-deposited Al-doped ZnO film without citrate ions showed rod array structure with increasing rod width as the Al concentration was increased. Meanwhile, Al-doped ZnO film deposited with addition of citrate ions changed to exhibit dense and continuous surface morphology with high transmittance of 85%. The lowest resistivity recorded for undoped and Al-doped ZnO film was 2.1 × 10-2 Ω cm and 5.9 × 10-3 Ω cm, after ultraviolet (UV) irradiation. The reason for the decreased resistivity is thought to be that Al-ion doping and the photocatalytic activity of ZnO contributed to improve the conductivity.

  3. Electron transport in Al-doped ZnO nanolayers obtained by atomic layer deposition

    Science.gov (United States)

    Blagoev, B. S.; Dimitrov, D. Z.; Mehandzhiev, V. B.; Kovacheva, D.; Terziyska, P.; Pavlic, J.; Lovchinov, K.; Mateev, E.; Leclercq, J.; Sveshtarov, P.

    2016-03-01

    Al-doped ZnO thin films with different Al content were prepared by atomic layer deposition (ALD). To carry out thermal ALD, diethyl zinc (DEZ) and tri-methyl aluminium (TMA) were used as Zn and Al precursors, respectively, and water vapor as oxidant. Various numbers n of DEZ and m TMA cycles was used to obtain different [ZnO] n [Al2O3] m films, where n = 100 - 95, m = 1 - 5. The X-ray diffraction analysis showed a predominantly (100) oriented polycrystalline phase for the ZnO:Al films with a low Al content (m = 1 - 3) and an amorphous structure for pure Al2O3. In ZnO:Al with a higher Al content (m = 4 - 6) the (100) reflection disappeared and the (002) peak increased. The resistivity of the films decreased with the increase in the Al content, reaching a minimum of 3.3×10-3 Ω cm at about 1.1 % Al2O3 for the [ZnO]99[Al2O3]2 sample; for higher dopant concentrations, the resistivity increased because of the increased crystal inhomogeneity due to axis reorientation.

  4. Properties of NiZnO Thin Films with Different Amounts of Al Doping

    Science.gov (United States)

    Kayani, Zohra N.; Fatima, Gulnaz; Zulfiqar, Bareera; Riaz, Saira; Naseem, Shahzad

    2017-10-01

    Transparent Al-doped NiZnO thin films have been fabricated by sol-gel dip coating and investigated using scanning electron microscopy, x-ray diffraction analysis, ultraviolet-visible-near infrared (UV-Vis-NIR) spectrophotometry, vibrating-sample magnetometry, and Fourier-transform infrared spectroscopy. The Al-doped NiZnO films consisted of ZnO hexagonal and α-Al2O3 rhombohedral phases as the Al incorporation was gradually increased from 1 at.% up to 3 at.%. A decrease in the optical bandgap from 3.90 eV to 3.09 eV was observed for films grown with Al content of 1 at.% to 2.5 at.%, but at 3 at.% Al, the bandgap increased to 3.87 eV. Optical transmittance of 96% was achieved for these transparent oxide films. Study of their magnetic properties revealed that increasing Al percentage resulted in enhanced ferromagnetism. The saturated magnetization increased with increasing Al percentage. The ferromagnetic properties of Al-doped NiZnO are mediated by electrons. The surface of the deposited thin films consisted of nanowires, nanorods, porous surface, and grains.

  5. Ultra-violet absorption induced modifications in bulk and nanoscale electrical transport properties of Al-doped ZnO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Mohit; Basu, Tanmoy; Som, Tapobrata, E-mail: tsom@iopb.res.in [SUNAG Laboratory, Institute of Physics, Sachivalaya Marg, Bhubaneswar 751 005 (India)

    2015-08-07

    Using conductive atomic force microscopy and Kelvin probe force microscopy, we study local electrical transport properties in aluminum-doped zinc oxide (ZnO:Al or AZO) thin films. Current mapping shows a spatial variation in conductivity which corroborates well with the local mapping of donor concentration (∼10{sup 20 }cm{sup −3}). In addition, a strong enhancement in the local current at grains is observed after exposing the film to ultra-violet (UV) light which is attributed to persistent photocurrent. Further, it is shown that UV absorption gives a smooth conduction in AZO film which in turn gives rise to an improvement in the bulk photoresponsivity of an n-AZO/p-Si heterojunction diode. This finding is in contrast to the belief that UV absorption in an AZO layer leads to an optical loss for the underneath absorbing layer of a heterojunction solar cell.

  6. Ultra-violet absorption induced modifications in bulk and nanoscale electrical transport properties of Al-doped ZnO thin films

    Science.gov (United States)

    Kumar, Mohit; Basu, Tanmoy; Som, Tapobrata

    2015-08-01

    Using conductive atomic force microscopy and Kelvin probe force microscopy, we study local electrical transport properties in aluminum-doped zinc oxide (ZnO:Al or AZO) thin films. Current mapping shows a spatial variation in conductivity which corroborates well with the local mapping of donor concentration (˜1020 cm-3). In addition, a strong enhancement in the local current at grains is observed after exposing the film to ultra-violet (UV) light which is attributed to persistent photocurrent. Further, it is shown that UV absorption gives a smooth conduction in AZO film which in turn gives rise to an improvement in the bulk photoresponsivity of an n-AZO/p-Si heterojunction diode. This finding is in contrast to the belief that UV absorption in an AZO layer leads to an optical loss for the underneath absorbing layer of a heterojunction solar cell.

  7. Structure and properties of Al-doped ZnO transparent conductive thin-films prepared by asymmetric bipolar pulsed DC reactive magnetron sputtering.

    Science.gov (United States)

    Hsu, Fu-Yung; Chen, Tse-Hao; Peng, Kun-Cheng

    2009-07-01

    Transparent conductive thin-films of aluminum-doped zinc oxide (AZO) were deposited on STN-glass substrates by an asymmetric bipolar pulsed DC (ABPDC) reactive magnetron sputtering system. Two different alloys, Zn-1.6 wt% Al and Zn-3.0 wt% Al, were used as the sputtering targets. The films consist of columnar grains with a preferred orientation of c-axis. Strong crystal distortion and high density stacking faults were observed in high resolution TEM micrographs. The full-width at half-maximum (FWHM) of the (002) rocking curve has a close relationship with the resistivity of the films; the smaller the FWHM, the lower the resistivity. The lowest resistivity of 7.0 x 10(-4) omega-cm was obtained from the film deposited with Zn-1.6 wt% Al target at 200 degrees C.

  8. Synthesis of Al doped ZnO nanoparticles by aqueous coprecipitation

    OpenAIRE

    Giovannelli, Fabien; Ngo Ndimba, P.; Diaz-Chao, P.; Motelica-Heino, Mikael; Raynal, P.I.; Autret, C.; Delorme, F.

    2014-01-01

    International audience; Al-doped ZnO particles were obtained by a simple route: soda addition in aqueous cationic solution. The effects of temperature, hydrolysis duration, reagent concentration and time were investigated. A non-topotactic reaction mechanism, involving firstly the precipitation of various hydroxide compounds depending on the route (low or high pH), followed by the dissolution-recrystallization of the hydroxide species into ZnO was demonstrated. The Al concentration in the fin...

  9. Genesis of flake-like morphology and dye-sensitized solar cell performance of Al-doped ZnO particles: a study

    Science.gov (United States)

    Sengupta, D.; Mondal, B.; Mukherjee, K.

    2017-03-01

    In dye-sensitized solar cell (DSSC) application, the particulate morphologies of photo-anode facilitate efficient dye loading and thus lead to better photo-conversion efficiency than their thin film counterpart. However, till date, the electronic and optical properties as well as the DSSC application of Al-doped ZnO (AZO) particles as photo-anode material is studied less than thin films. Herein, phase formation behavior, morphology evolution, optical properties, and dye-sensitized solar cell performance of wet chemically prepared ZnO and AZO (dopant level: 1-4 mol%) particles are studied. It is found that Al doping modulates significantly the ZnO morphology which in turn results the maximum dye adsorption as well as best photo-conversion efficiency at optimum dopant concentration. Specifically, the nanoparticle of ZnO turns predominantly to flake-like morphology with a higher surface area when 2 mol% Al is doped. Such morphology modulation is expected, since the crystallinity, lattice parameters, and lattice strain of ZnO changes appreciably with Al doping. The variations of optical properties (absorbance, diffused reflectance, and band gap) of AZO materials as compared to primitive ZnO are also identified through UV-vis studies. An attempt is made here to correlate the structural features with the photovoltaic performances of ZnO and AZO.

  10. Electronic structure and optical properties of Al-doped ZnO.

    Science.gov (United States)

    Qu, Xiurong; Lü, Shuchen; Jia, Dechang; Fu, Shufang

    2011-11-01

    Impure ZnO materials are of great interest in optic and electronic applications. In this work, the effects of Al-doping on the electronic structures of ZnO system are investigated in detail. We find that the crystal structure strains significantly due to the introduction of Al impurity. On the other hand, the electronic band structures show that the position of the Fermi level moves upwards and the bands split near the band gap due to the introduction of Al. This is attributed to the interaction between Al3p and Zn4s orbital, which tend to drive the system towards semimetal. Photoluminescence (PL) studies indicate that the Al-doped ZnO samples have a high density of defects. This can be explained qualitatively by the above analysis on electronic structure.

  11. Tuning of refractive index in Al-doped ZnO films by rf-sputtering using oblique angle deposition

    Science.gov (United States)

    Martín-Tovar, E. A.; Denis-Alcocer, E.; Díaz, E. Chan y.; Castro-Rodríguez, R.; Iribarren, A.

    2016-07-01

    Al-doped ZnO thin films were grown by rf-sputtering using the oblique angle deposition technique. The films are formed by tilted dense nanocolumns according to the substrate inclination during the growth. The film refractive index changed 16% due to the film nanocolumn tilt from 0° to 13.5°, which corresponded to substrate inclination from 0° to 75°, respectively. Band gap energy was found to diminish, which was associated to local redistribution of Al concentration x in the Al x Zn1-x O solid solution around the x \\cong 0.02 average.

  12. Stress-dependent band gap shift and quenching of defects in Al-doped ZnO films

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Bhupendra K; Khare, Neeraj, E-mail: nkhare@physics.iitd.ernet.i [Department of Physics, IIT Delhi, New Dehi-110016 (India)

    2010-11-24

    Al-doped ZnO (AZO) films were deposited on quartz substrates by the ultrasonically assisted chemical vapour deposition technique. The undoped ZnO film was found to be subjected to a stress which increases initially up to 3% Al doping, and then a slight decrease was observed for 5% Al doping. The band gap of AZO shows a blue shift up to 3% of Al doping as compared with the undoped ZnO. The blue shift in the band gap of the AZO films cannot be understood in the framework of Burstein-Moss shift and has been attributed to an increase in the stress present in the film. The photoluminescence spectrum of the undoped ZnO film shows a wide peak in the visible region which is suppressed with a small red shift after Al doping in the ZnO film. A detailed analysis of photoluminescence of ZnO and AZO films indicates suppression of zinc interstitials (Zn{sub i}) and oxygen vacancies (V{sub O}) and creation of oxygen interstitial (O{sub i}) defects after Al doping in ZnO films. X-ray photoelectron spectroscopy study also reveals suppression of oxygen vacancy related defects after Al doping in the ZnO film. The presence of Al in the ZnO matrix seems to change the defect equilibria leading to a suppression of Zn{sub i} and V{sub O} and enhancement of O{sub i} defects. The suppression of Zn{sub i} defects is correlated with the increase in stress in Al-doped ZnO films.

  13. Determining the thermophysical properties of Al-doped ZnO nanoparticles by the photoacoustic technique

    Institute of Scientific and Technical Information of China (English)

    T.A.El-Brolossy; O.Saber; S.S.Ibrahim

    2013-01-01

    The thermal conductivity and specific heat capacity of undoped and Al-doped (1-10 at.%) ZnO nanoparticles prepared using the solvent thermal method are determined by measuring both thermal diffusivity and thermal effusivity of a pressed powder compact of the prepared nanoparticles by using the laser-induced photoacoustic technique.The impact of Al doping versus the microstructure of the samples on such thermal parameters has been investigated.The results reveal an obvious enhancement in the specific heat capacity when decreasing the particle size,while the effect of Al doping on the specific heat capacity is minor.The measured thermal conductivities are about one order of magnitude smaller than that of the bulk ZnO due to several nested reducing heat transfer mechanisms.The results also show that Al doping significantly influences the thermal resistance.Using a simple thermal impedance model,the added thermal resistance due to Al dopant has been estimated.

  14. Study on synthesis and optical properties of Al-doped ZnO hierarchical nanostructures

    OpenAIRE

    2011-01-01

    Highly densified Al-doped ZnO (denoted as Al-ZnO) hierarchical nanostructures were synthesized on transparent quartz substrate by chemical vapor deposition. It is found that the heating temperature plays a key role on controlling the morphologies of the Al-ZnO hierarchical nanostructures through a temperature dependent migration of Al atoms. Such uneven distribution of Al element in the hierarchical nanostructures is clearly evidenced by the x-ray photoelectron spectrum (XPS) measurements. Th...

  15. Electrical stability of Al-doped ZnO transparent electrode prepared by sol-gel method

    Energy Technology Data Exchange (ETDEWEB)

    Tabassum, Samia, E-mail: shawon14@gmail.com; Yamasue, Eiji; Okumura, Hideyuki; Ishihara, Keiichi N.

    2016-07-30

    Highlights: • Al-doped ZnO thin film was deposited by sol-gel method in different annealing temperature and duration. • We examined the environmental stability in ambient and damp heat condition. • We investigated chemical state of thin film. • Better stability was observed in the film annealed at high temperature (600 °C) along with longer duration (120 min). • An ultrathin aluminum oxide layer formation was predicted by XPS measurement which protects further oxidation and improves stability. - Abstract: Al-doped zinc oxide (AZO) thin films have been considered as a promising alternative to tin doped indium oxide (ITO), which is currently used in various optoelectronic applications. However, the environmental stability of AZO film is not satisfactory, in that the resistivity is significantly increases in air. Here, we investigate the resistivity stability of AZO thin films prepared by sol-gel method using various annealing temperatures and durations. The degradation of resistivity property was observed for AZO films stored in ambient or damp heat environment, where the degradation rate was influenced by annealing temperature. A significant improvement of electrical stability was attained in AZO films that were prepared at high annealing temperature. The films, which showed the highest and the lowest increasing rate of resistivity, were further characterized in detail to shed light on the possible mechanisms explaining the improved stability through crystallinity, surface morphology and elemental state of the thin film.

  16. Thermoelectric properties of Al-doped ZnO: experiment and simulation

    Science.gov (United States)

    Jantrasee, S.; Moontragoon, P.; Pinitsoontorn, S.

    2016-09-01

    Advancement in doping other elements, such as Ce, Dy, Ni, Sb, In and Ga in ZnO[1], have stimulated great interest for high-temperature thermoelectric application. In this work, the effects of Al-doping in a ZnO system on the electronic structure and thermoelectric properties are presented, by experiment and calculation. Nanosized powders of Zn1-x Al x O (x = 0,0.01, 0.02, 0.03 and 0.06) were synthesized by hydrothermal method. From XRD results, all samples contain ZnO as the main phase and ZnAl2O4 (spinel phase) peaks were visible when Al additive concentrations were just 6 at%. The shape of the samples changed and the particle size decreased with increasing Al concentration. Seebeck coefficients, on the other hand, did not vary significantly. They were negative and the absolute values increased with temperature. However, the electrical resistivity decreased significantly for higher Al content. The electronic structure calculations were carried out using the open-source software package ABINIT[2], which is based on DFT. The energy band gap, density of states of Al-doped ZnO were investigated using PAW pseudopotential method within the LDA + U. The calculated density of states was then used in combination with the Boltzmann transport equation[3] to calculate the thermoelectric parameters of Al-doped ZnO. The electronic band structures showed that the position of the Fermi level of the doped sample was shifted upwards in comparison to the undoped one. After doping Al in ZnO, the energy band gap was decreased, Seebeck coefficient and electrical conductivity were increased. Finally, the calculated results were compared with the experimental results. The good agreement of thermoelectric properties between the calculation and the experimental results were obtained.

  17. Large lateral photovoltaic effect observed in nano Al-doped ZnO films.

    Science.gov (United States)

    Lu, Jing; Wang, Hui

    2011-07-18

    Zinc oxide (ZnO), including a variety of metal-doped ZnO, as one kind of most important photoelectric materials, has been widely investigated and received enormous attention for a series of applications. In this work, we report a new finding which we call as lateral photovoltaic effect (LPE) in a nano Al-doped ZnO (ZAO) film based on ZAO/SiO2/Si homo-heterostructure. This large and stable LPE observed in ZAO is an important supplement to the existing ZnO properties. In addition, all data and analyses demonstrate ZAO film can also be a good candidate for new type position-sensitive detector (PSD) devices.

  18. CdS nanoparticles sensitization of Al-doped ZnO nanorod array thin film with hydrogen treatment as an ITO/FTO-free photoanode for solar water splitting.

    Science.gov (United States)

    Hsu, Chih-Hsiung; Chen, Dong-Hwang

    2012-10-25

    Aluminum-doped zinc oxide (AZO) nanorod array thin film with hydrogen treatment possesses the functions of transparent conducting oxide thin film and 1-D nanostructured semiconductor simultaneously. To enhance the absorption in the visible light region, it is sensitized by cadmium sulfide (CdS) nanoparticles which efficiently increase the absorption around 460 nm. The CdS nanoparticles-sensitized AZO nanorod array thin film with hydrogen treatment exhibits significantly improved photoelectrochemical property. After further heat treatment, a maximum short current density of 5.03 mA cm-2 is obtained under illumination. They not only are much higher than those without CdS nanoparticles sensitization and those without Al-doping and/or hydrogen treatment, but also comparable and even slightly superior to some earlier works for the CdS-sensitized zinc oxide nanorod array thin films with indium tin oxide (ITO) or fluorine-doped tin oxide (FTO) as substrates. This demonstrated successfully that the AZO nanorod array thin film with hydrogen treatment is quite suitable as an ITO/FTO-free photoanode and has great potentials in solar water splitting after sensitization by quantum dots capable of visible light absorption.

  19. On the transparent conducting oxide Al doped ZnO: First Principles and Boltzmann equations study

    Energy Technology Data Exchange (ETDEWEB)

    Slassi, A. [Institute of Nanomaterials and Nanotechnology, MAScIR, Rabat (Morocco); LMPHE (URAC 12), Faculté des Sciences, Université Mohammed V-Agdal, Rabat (Morocco); Naji, S. [LMPHE (URAC 12), Faculté des Sciences, Université Mohammed V-Agdal, Rabat (Morocco); Department of Physics, Faculty of Science, Ibb University, Ibb (Yemen); Benyoussef, A. [Institute of Nanomaterials and Nanotechnology, MAScIR, Rabat (Morocco); LMPHE (URAC 12), Faculté des Sciences, Université Mohammed V-Agdal, Rabat (Morocco); Hamedoun, M., E-mail: hamedoun@hotmail.com [Institute of Nanomaterials and Nanotechnology, MAScIR, Rabat (Morocco); El Kenz, A. [LMPHE (URAC 12), Faculté des Sciences, Université Mohammed V-Agdal, Rabat (Morocco)

    2014-08-25

    Highlights: • The incorporation of Al in ZnO increases the optical band edge absorption. • Incorporated Al creates shallow donor states of Al-3s around Fermi level. • Transmittance decreases in the visible and IR regions, while it increases in the UV region. • Electrical conductivity increases and reaches almost the saturation for high concentration of Al. - Abstract: We report, in this work, a theoretical study on the electronic, optical and electrical properties of pure and Al doped ZnO with different concentrations. In fact, we investigate these properties using both First Principles calculations within TB-mBJ approximation and Boltzmann equations under the constant relaxation time approximation for charge carriers. It is found out that, the calculated lattice parameters and the optical band gap of pure ZnO are close to the experimental values and in a good agreement with the other theoretical studies. It is also observed that, the incorporations of Al in ZnO increase the optical band edge absorption which leads to a blue shift and no deep impurities levels are induced in the band gap as well. More precisely, these incorporations create shallow donor states around Fermi level in the conduction band minimum from mainly Al-3s orbital. Beside this, it is found that, the transmittance is decreased in the visible and IR regions, while it is significantly improved in UV region. Finally, our calculations show that the electrical conductivity is enhanced as a result of Al doping and it reaches almost the saturation for high concentration of Al. These features make Al doped ZnO a transparent conducting electrode for optoelectronic device applications.

  20. Effects of free electrons and quantum confinement in ultrathin ZnO films: a comparison between undoped and Al-doped ZnO.

    Science.gov (United States)

    Li, X D; Chen, T P; Liu, P; Liu, Y; Leong, K C

    2013-06-17

    Band gaps and exciton binding energies of undoped and Al-doped ZnO thin films were determined from optical absorption measurement based on the Elliott's exciton absorption theory. As compared to the undoped films, the doped films exhibit a band gap expansion and a reduction in the exciton binding energies due to the free electron screening effect, which suppresses the excitonic absorption and results in a blue shift of the absorption edge. The undoped and doped films show the same quantum size dependence, i.e. both the exciton binding energies and band gap energies increase with decreasing grain size of the oxides.

  1. Al-doped ZnO films deposited on a slightly reduced buffer layer by reactive dc unbalanced magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Kusayanagi, Minehide; Uchida, Azusa; Oka, Nobuto; Jia, Junjun [Graduate School of Science and Engineering, Aoyama Gakuin University, 5-10-1 Fuchinobe, Sagamihara, Kanagawa 252-5258 (Japan); Nakamura, Shin-ichi [Center for Instrumental Analysis, Aoyama Gakuin University, 5-10-1 Fuchinobe, Sagamihara, Kanagawa 252-5258 (Japan); Shigesato, Yuzo, E-mail: yuzo@chem.aoyama.ac.jp [Graduate School of Science and Engineering, Aoyama Gakuin University, 5-10-1 Fuchinobe, Sagamihara, Kanagawa 252-5258 (Japan)

    2014-03-31

    Al-doped ZnO (AZO) films were deposited on a fused silica glass substrate by reactive dc unbalanced magnetron sputtering using a Zn–Al (Al: 3.6 at.%) alloy target with an impedance control system. A very thin slightly reduced AZO buffer layer was inserted between the glass substrate and AZO films. For the AZO films deposited at 200 °C, the lowest resistivity in the absence of the buffer layer was 8.0 × 10{sup −4} Ω cm, whereas this was reduced to 5.9 × 10{sup −4} Ω cm after introducing a 5-nm-thick buffer layer. The transmittance for all the films was above 80% in the visible region. The effects of the buffer layer were analysed and discussed in detail. It is found that the insertion of the buffer layer can improve the crystallinity of the AZO film. - Highlights: • Al-doped ZnO (AZO) films with AZO buffer layers were deposited. • Reactive dc unbalance magnetron sputtering with impedance control was used. • Insertion of a buffer layer can lead to a lower resistivity. • Insertion of a buffer layer improved the crystallinity of AZO films.

  2. Ferromagnetism induced by the charge transfer in Al-doped ZnO nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Yanyu; Zhou, Wei; Wu, Ping, E-mail: pingwu@tju.edu.cn

    2014-12-05

    Highlights: • A systematical investigation has been carried out on Zn{sub 1−x}Al{sub x}O system. • Our results confirm that Zn{sub 1−x}Al{sub x}O nanoparticles are magnetic. • The magnetism originates from charge transfer between different cations. • The accordant conclusion is drawn both theoretically and experimentally. • The ferromagnetism would render it to realize more comprehensive applications. - Abstract: The mechanism of ferromagnetism in Al-doped ZnO was investigated both theoretically and experimentally. The density functional theory calculations were carried out to explore the electronic structure origin of ferromagnetism. The Al dopants both doping in a bulk ZnO and absorbing on the ZnO surface are taken into account. Based on the Bader charge analysis for the clear and adsorbed ZnO surface, it is found that the ionic state of Zn decreases after Al doping. The corresponding room temperature ferromagnetism was also confirmed by experiments. Moreover, the experimental analysis rules out that the ferromagnetism results from zinc vacancy or oxygen vacancy. Thus, the physical origin of the induced magnetism was indicated originating from the charge transfer between Zn atoms and adsorbed Al atoms.

  3. Thermoelectric properties of Al-doped Mg2Si thin films deposited by magnetron sputtering

    Science.gov (United States)

    Chen, Zhi-jian; Zhou, Bai-yang; Li, Jian-xin; Wen, Cui-lian

    2016-11-01

    The Al-doped Mg2Si thin films were fabricated by two-target alternative magnetron sputtering technique, and the influences of different Al doping contents on the thermoelectric properties of Al-doped Mg2Si thin films were investigated. The compositions, crystal structures, electronic transport properties and thermoelectric properties of the thin films were examined using energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), Hall coefficient measurement and Seebeck coefficient measurement system, respectively. The EDS results show that the thin films doped with Al target sputtering power of 30 W, 60 W and 90 W have the Al content of 0.68 at.%, 1.56 at.% and 2.85 at.%, respectively. XRD results indicate that the diffraction peaks of Mg2Si become stronger with increasing Al dopant. The results of Hall coefficient measurement and Seebeck coefficient measurement system reveal that all the samples are n-type. The conductivities of Al-doped Mg2Si thin films are significantly greater than that of undoped Mg2Si thin film, and increase with increasing Al doping content. With the increase of temperature, the absolute value of the Seebeck coefficients of Mg2Si base thin films increase firstly and then decrease. The maximum power factor obtained is 3.8 mW m-1 k-2 for 1.56 at.% Al-doped Mg2Si thin film at 573 K.

  4. Morphological properties of Al-doped ZnO nano/microstructures

    Science.gov (United States)

    Kim, Kyung Ho; Umakoshi, Tomoyuki; Abe, Yoshio; Kawamura, Midori; Kiba, Takayuki

    2016-03-01

    We discussed the morphological properties of Al-doped zinc oxide (Al-ZnO) microrods grown on a ZnO seed layer and precipitation particles and compared them with undoped ZnO samples. The ZnO nanorods grown on a ZnO seed layer were dense and perpendicular to the surface of the substrate, i.e., fluorine-doped tin oxide (FTO). In contrast the Al-ZnO grew as larger microrods, and the rods were sparsely and obliquely arranged. Precipitation particles synthesized in the ZnO solution through homogeneous nucleation had flower-like structures assembled from the rods and individual rods with lengths of several micrometers. Al-ZnO precipitation particles consisted of rods with length of several micrometers and hexagonal nanoplates. Fourier transform infrared (FTIR) analysis results showed that the rods and precipitation particles had the good chemical properties of ZnO. Both size and morphology of the rods could be effectively controlled by adding aluminum nitrate (Al(NO3)3) as dopant in the ZnO rod solution.

  5. Growth and optical properties of ZnO nanorod arrays on Al-doped ZnO transparent conductive film

    OpenAIRE

    Lin, Suanzhi; Hu, Hailong; Zheng, Weifeng; Qu, Yan; Lai, Fachun

    2013-01-01

    ZnO nanorod arrays (NRAs) on transparent conductive oxide (TCO) films have been grown by a solution-free, catalyst-free, vapor-phase synthesis method at 600°C. TCO films, Al-doped ZnO films, were deposited on quartz substrates by magnetron sputtering. In order to study the effect of the growth duration on the morphological and optical properties of NRAs, the growth duration was changed from 3 to 12 min. The results show that the electrical performance of the TCO films does not degrade after t...

  6. Structure and thermoelectric properties of Al-doped ZnO films prepared by thermal oxidization under high magnetic field

    Science.gov (United States)

    Liu, Shiying; Peng, Sunjuan; Ma, Jun; Li, Guojian; Qin, Xuesi; Li, Mengmeng; Wang, Qiang

    2017-04-01

    This paper studies the effects of high magnetic field (HMF) on the structure, optical and thermoelectric properties of the doped ZnO thin films. The results show that both Al dopant and application of HMF can affect the crystal structure, surface morphology, elemental distribution and so on. The particles of the thin films become small and regular by doping Al. The ZnO films oxidized from the Au/Zn bilayer have needle structure. The ZnO films oxidized from the Au/Zn-Al bilayer transform to spherical from hexagonal due to the application of HMF. The transmittance decreases with doping Al because of the opaque of Al element and decreases with the application of HMF due to the dense structure obtained under HMF. Electrical resistivity (ρ) of the ZnO films without Al decreases with increasing measurement temperature (T) and is about 1.5 × 10-3 Ω·m at 210 °C. However, the ρ of the Al-doped ZnO films is less than 10-5 Ω·m. The Seebeck coefficient (S) of the films oxidized from the Au/Zn-Al films reduces with increasing T. The S values oxidized under 0 T and 12 T conditions are 2.439 μV/K and -3.415 μV/K at 210 °C, respectively. Power factor reaches the maximum value (3.198 × 10-4 W/m·K2) at 210 °C for the film oxidized under 12 T condition. These results indicate that the Al dopant and the application of HMF can be used to control structure and thermoelectric properties of doped ZnO films.

  7. Study on synthesis and optical properties of Al-doped ZnO hierarchical nanostructures

    Directory of Open Access Journals (Sweden)

    X. H. Wang

    2011-03-01

    Full Text Available Highly densified Al-doped ZnO (denoted as Al-ZnO hierarchical nanostructures were synthesized on transparent quartz substrate by chemical vapor deposition. It is found that the heating temperature plays a key role on controlling the morphologies of the Al-ZnO hierarchical nanostructures through a temperature dependent migration of Al atoms. Such uneven distribution of Al element in the hierarchical nanostructures is clearly evidenced by the x-ray photoelectron spectrum (XPS measurements. The obtained Al-ZnO hierarchical nanostructures have transmittance of above 60% in the visible region. The photoluminescence (PL spectra at low-temperature (20 K were also measured.

  8. Synthesis of High-Quality Al-Doped ZnO Nanoink

    OpenAIRE

    Thu, Tran V.; Maenosono, Shinya

    2010-01-01

    Al-doped ZnO (AZO) nanoparticles (NPs) have been synthesized via the thermal decomposition of metal acetylacetonate precursors in a nonoxygen and nonpolar solvent. Long-chain alkyl amines have been utilized to terminate the growth of AZO NPs and to stabilize them. The NPs have been characterized by a number of techniques as monocrystalline, exhibiting a hexagonal (wurtzite) structure with sizes from 8 to 13 nm. The composition of Al in the resulting NP is related solely to the composition of ...

  9. Investigation of the interrelation between the chemical state and the electric properties in Al-doped ZnO films

    Science.gov (United States)

    Wang, Jinzhao; Ni, Dongfang; Zhang, Tianjin; Wang, Duofa; Liang, Kun

    2015-09-01

    Transparent conducting Al-doped ZnO (AZO) thin films were prepared on glass substrates by radio frequency magnetron sputtering in pure Ar. The influence of the annealing atmosphere on the microstructure, chemical state, electric and optical properties of the AZO films was investigated with X-ray diffraction, field-emission scanning electron microscopy, X-ray photoelectron spectroscopy and Hall measurements. The AZO thin films annealed under vacuum had the highest carrier concentration of 2.488 × 1020 cm-3 and a Hall mobility of 16.35 cm2 V-1 s-1, while the AZO thin films annealed in air had the lowest carrier concentration of 4.182 × 1017 cm-3 and a Hall mobility of 2.375 cm2 V-1 s-1. The fitted narrow-scan O1 s spectra revealed that O1 s was composed of three components. The AZO thin films annealed under vacuum appeared to have a higher proportion of medium binding energy which correspond to O2- ions in the oxygen-deficient regions within the ZnO matrix, and have a lower proportion of high binding energy component which correspond to loosely bound chemisorbed oxygen. It believed that the oxygen vacancies and chemisorbed oxygen of the films played an important role in the electrical conductance. The carrier concentration increased with the formation of oxygen vacancies. The Hall mobility increased with desorption of the loosely bound oxygen.

  10. Room-temperature violet luminescence and ultraviolet photodetection of Sb-doped ZnO/Al-doped ZnO homojunction array

    OpenAIRE

    Chen, Wei-Jen; Wu, Jen-Kai; Lin, Jheng-Cyuan; Lo, Shun-Tsung; Lin, Huang-De; Hang, Da-Ren; Shih, Ming Feng; Liang, Chi-Te; Chang, Yuan Huei

    2013-01-01

    A Sb-doped ZnO microrod array was fabricated on an Al-doped ZnO thin film by electrodeposition. Strong violet luminescence, originated from free electron-to-acceptor level transitions, was identified by temperature-dependent photoluminescence measurements. This acceptor-related transition was attributed to substitution of Sb dopants for Zn sites, instead of O sites, to form a complex with two Zn vacancies (VZn), the SbZn-2VZn complex. This SbZn-2VZn complex has a lower formation energy and ac...

  11. Plasma versus thermal annealing for the Au-catalyst growth of ZnO nanocones and nanowires on Al-doped ZnO buffer layers

    Science.gov (United States)

    Güell, Frank; Martínez-Alanis, Paulina R.; Roso, Sergio; Salas-Pérez, Carlos I.; García-Sánchez, Mario F.; Santana, Guillermo; Marel Monroy, B.

    2016-06-01

    We successfully synthesized ZnO nanocones and nanowires over polycrystalline Al-doped ZnO (AZO) buffer layers on fused silica substrates by a vapor-transport process using Au-catalyst thin films. Different Au film thicknesses were thermal or plasma annealed in order to analyze their influence on the ZnO nanostructure growth morphology. Striking differences have been observed. Thermal annealing generates a distribution of Au nanoclusters and plasma annealing induces a fragmentation of the Au thin films. While ZnO nanowires are found in the thermal-annealed samples, ZnO nanocones and nanowires have been obtained on the plasma-annealed samples. Enhancement of the preferred c-axis (0001) growth orientation was demonstrated by x-ray diffraction when the ZnO nanocones and nanowires have been grown over the AZO buffer layer. The transmittance spectra of the ZnO nanocones and nanowires show a gradual increase from 375 to 900 nm, and photoluminescence characterization pointed out high concentration of defects leading to observation of a broad emission band in the visible range from 420 to 800 nm. The maximum emission intensity peak position of the broad visible band is related to the thickness of the Au-catalyst for the thermal-annealed samples and to the plasma power for the plasma-annealed samples. Finally, we proposed a model for the plasma versus thermal annealing of the Au-catalyst for the growth of the ZnO nanocones and nanowires. These results are promising for renewable energy applications, in particular for its potential application in solar cells.

  12. Photoluminescence, FTIR and X-ray diffraction studies on undoped and Al-doped ZnO thin films grown on polycrystalline {alpha}-alumina substrates by ultrasonic spray pyrolysis

    Energy Technology Data Exchange (ETDEWEB)

    Djelloul, A., E-mail: djelloulabdelkader@yahoo.f [LASPI2A Laboratoire des Structures, Proprietes et Interactions Inter Atomiques, Centre Universitaire Khenchela (Algeria); Aida, M-S. [Laboratoire des Couches minces et Interface, Universite de Constantine (Algeria); Bougdira, J. [Institut Jean Lamour, UMR 7198 CNRS, Nancy Universite, UPV-Metz, Faculte des Sciences et Techniques, B.P. 239, Bd des Aiguillettes, 54506 Vandoeuvre-les-Nancy (France)

    2010-11-15

    Undoped and aluminum-doped zinc oxide (ZnO) thin films have been grown on polycrystalline {alpha}-alumina substrates by ultrasonic spray pyrolysis (USP) technique using zinc acetate dihydrate and aluminum chloride hexahydrate (Al source) dissolved in methanol, ethanol and deionized water. A number of techniques, including X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, and photoluminescence (PL) were used to characterize the obtained ZnO thin films. It was seen that the orientation changed with increase in substrate temperature. During the ZnO deposition Zn source reacted with polycrystalline {alpha}-Al{sub 2}O{sub 3} substrate to form an intermediate ZnAl{sub 2}O{sub 4} spinel layer. It has been interestingly found that the intensity of green emission at 2.48 eV remarkably increased when the obtained ZnO:Al films were deposited at 380 {sup o}C. The FTIR absorbance intensity of spectroscopic band at 447{+-}6 cm{sup -1} is very sensitive to oxygen sublattice disorder resulting from non-stoichiometry, which is consistent with the result of PL characterization.

  13. Effect of deposition temperature on the properties of Al-doped ZnO films prepared by pulsed DC magnetron sputtering for transparent electrodes in thin-film solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Doo-Soo; Park, Ji-Hyeon; Shin, Beom-Ki; Moon, Kyeong-Ju [Information and Electronic Materials Research Laboratory, Department of Materials Science and Engineering, Yonsei University, 134 Shinchon-dong, Seodaemun-gu, Seoul 120-749 (Korea, Republic of); Son, Myoungwoo [Department of Nanobio Materials and Electronics, Gwangju Institute of Science and Technology, Gwangju 500-712 (Korea, Republic of); Ham, Moon-Ho [Department of Nanobio Materials and Electronics, Gwangju Institute of Science and Technology, Gwangju 500-712 (Korea, Republic of); School of Materials Science and Engineering, Gwangju Institute of Science and Technology, Gwangju 500-712 (Korea, Republic of); Lee, Woong [School of Nano and Advanced Materials Engineering, Changwon National University, 9 Sarim-Dong, Changwon, Gyeongnam 641-773 (Korea, Republic of); Myoung, Jae-Min, E-mail: jmmyoung@yonsei.ac.kr [Information and Electronic Materials Research Laboratory, Department of Materials Science and Engineering, Yonsei University, 134 Shinchon-dong, Seodaemun-gu, Seoul 120-749 (Korea, Republic of)

    2012-10-15

    Highlights: Black-Right-Pointing-Pointer Surface-textured AZO films were achieved by combining PDMS method with wet etching. Black-Right-Pointing-Pointer The AZO film deposited at 230 Degree-Sign C by PDMS exhibited the best performance. Black-Right-Pointing-Pointer It is due to the higher plasma density supplied from PDMS system. Black-Right-Pointing-Pointer Wet etching of the films produces a crater-like rough surface morphology. - Abstract: A simple but scalable approach to the production of surface-textured Al-doped ZnO(AZO) films for low-cost transparent electrode applications in thin-film solar cells is introduced in this study by combining pulsed dc magnetron sputtering (PDMS) with wet etching in sequence. First, structural, electrical, and optical properties of the AZO films prepared by a PDMS were investigated as functions of deposition temperature to obtain transparent electrode films that can be used as indium-free alternative to ITO electrodes. Increase in the deposition temperature to 230 Degree-Sign C accompanied the improvement in crystalline quality and doping efficiency, which enabled the lowest electrical resistivity of 4.16 Multiplication-Sign 10{sup -4} {Omega} cm with the carrier concentration of 1.65 Multiplication-Sign 10{sup 21} cm{sup -3} and Hall mobility of 11.3 cm{sup 2}/V s. The wet etching of the films in a diluted HCl solution resulted in surface roughening via the formation of crater-like structures without significant degradation in the electrical properties, which is responsible for the enhanced light scattering capability required for anti-reflective electrodes in thin film solar cells.

  14. Glancing angle deposited Al-doped ZnO nanostructures with different structural and optical properties

    Energy Technology Data Exchange (ETDEWEB)

    Yildiz, A., E-mail: yildizab@gmail.com [Department of Physics and Astronomy, University of Arkansas at Little Rock, Little Rock, AR 72204 (United States); Department of Energy Systems Engineering, Faculty of Engineering and Natural Sciences, Yıldırım Beyazıt University, Ankara (Turkey); Cansizoglu, H. [Department of Physics and Astronomy, University of Arkansas at Little Rock, Little Rock, AR 72204 (United States); Turkoz, M. [Department of Physics and Astronomy, University of Arkansas at Little Rock, Little Rock, AR 72204 (United States); Department of Electrical-Electronic Engineering, Faculty of Engineering, University of Karabuk, Karabuk (Turkey); Abdulrahman, R.; Al-Hilo, Alaa; Cansizoglu, M.F.; Demirkan, T.M.; Karabacak, T. [Department of Physics and Astronomy, University of Arkansas at Little Rock, Little Rock, AR 72204 (United States)

    2015-08-31

    Al-doped ZnO (AZO) nanostructure arrays with different shapes (tilted rods, vertical rods, spirals, and zigzags) were fabricated by utilizing glancing angle deposition (GLAD) technique in a DC sputter growth unit at room temperature. During GLAD, all the samples were tilted at an oblique angle of about 90° with respect to incoming flux direction. In order to vary the shapes of nanostructures, each sample was rotated at different speeds around the substrate normal axis. Rotation speed did not only affect the shape but also changed the microstructural and optical properties of GLAD AZO nanostructures. The experimental results reveal that GLAD AZO nanostructures of different shapes each have unique morphological, crystal structure, mechanical, and optical properties determined by scanning electron microscopy, X-ray diffraction, transmission, and reflectance measurements. Vertical nanorods display the largest grain size, minimum strain, lowest defect density, and highest optical transmittance compared to the other shapes. Growth dynamics of GLAD has been discussed to explain the dependence of structural and optical properties of nanostructures on the substrate rotation speed. - Highlights: • Al-doped ZnO (AZO) nanostructures with different shapes were fabricated. • They have unique morphological, crystal structure, and optical properties. • Vertical AZO nanorods show an enhanced optical transmittance.

  15. Pulsed electron beam deposition of transparent conducting Al-doped ZnO films

    Energy Technology Data Exchange (ETDEWEB)

    Quang, Pham Hong, E-mail: phquang2711@yahoo.com [Hanoi University of Science, Vietnam National University, Hanoi, 334 Nguyen Trai, Thanh Xuan, Hanoi (Viet Nam); Sang, Ngo Dinh [National University of Civil Engineering, 55 Giai Phong Street, Hai Ba Trung, Hanoi (Viet Nam); Ngoc, Do Quang [Hanoi University of Science, Vietnam National University, Hanoi, 334 Nguyen Trai, Thanh Xuan, Hanoi (Viet Nam)

    2012-08-31

    Good quality transparent conducting Al-doped ZnO films were deposited on quartz substrates from a high purity target using pulsed electron deposition (PED). Two series of films were made, one deposited at room temperature but at four pressures, viz., 0.7, 1.3, 2.0 and 2.7 Pa of oxygen and one deposited at 1.3 Pa oxygen pressure but at the substrate temperature ranged from room temperature to 600 Degree-Sign C. In order to evaluate the effect of substrate temperature and oxygen pressure on the properties of obtained films, various characterization techniques were employed including X-ray diffraction, stylus profiler, scanning electron microscope, optical spectrophotometer and electrical resistivity. For the first series films, the optimal oxygen pressure of 1.3 Pa was found to bring about the appropriate energetic deposition atoms which results in the best crystallinity. For the second series films, the lowest resistivity was obtained in the film grown at 400 Degree-Sign C. An attempt was made to reduce the resistivity by lowering the oxygen pressure to 0.5 Pa which was the lower limit of working pressure of the PED system. The obtained results indicate that PED is a suitable technique for growing transparent conducting ZnO films. - Highlights: Black-Right-Pointing-Pointer Transparent conducting Al-doped ZnO films grown by pulsed electron deposition (PED). Black-Right-Pointing-Pointer The film properties were found to depend strongly on the deposition conditions. Black-Right-Pointing-Pointer The best film was grown at the oxygen pressure of 0.5 Pa and at 400 Degree-Sign C. Black-Right-Pointing-Pointer PED is found to be a suitable technique for growing transparent conducting ZnO films.

  16. Determination of the electrically active Al fraction in Al doped ZnO grown by pulsed reactive magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Cornelius, Steffen; Vinnichenko, Mykola; Munnik, Frans; Heller, Rene; Kolitsch, Andreas; Moeller, Wolfhard [Helmholtz Zentrum Dresden-Rossendorf, Dresden (Germany)

    2011-07-01

    Al-doped ZnO (AZO) films which combine maximum carrier mobility, moderate free electron densities and high surface roughness are of special interest for application as transparent front electrode in thin film solar cells. They posses high transmission in the near infrared spectral range, close to the bandgap energy of absorber materials like Si (Eg=1.11 eV), and enable a superior light trapping behaviour. A key to tailor AZO film properties is understanding the mechanisms and effects of the Al-dopant incorporation into the ZnO matrix. It is well accepted that the mobilities in degenerately doped AZO are limited by ionized impurity scattering. A way to overcome this limitation would be to reduce the density of ionized impurities which either do not donate electrons themselves or compensate the Al donor. This is equivalent to increasing the fraction of electrically active Al in the ZnO host material. Systematic and quantitative information on this topic is still missing in literature. Therefore this work focuses on quantification of the Al concentration by ion beam analysis methods in conjuction with Hall-effect measurements for AZO films grown by reactive pulsed magnetron sputtering. The influence of parameters like target composition and substrate temperature on the Al activation is discussed.

  17. Room temperature DC magnetron sputtering deposition and field emission of Al-doped ZnO films

    Energy Technology Data Exchange (ETDEWEB)

    Ye, Fan; Cai, Xing-Min; Zhang, Dong-Ping; Fan, Ping; Liu, Li-Jun [School of Physical Science and Technology and Shenzhen Key Laboratory of Sensor Technologies, Shenzhen University, Shenzhen 518060 (China); Dai, Fu-Ping [Department of Applied Physics, Northwestern Polytechnic University, Xian 710072 (China)

    2011-08-15

    Al doped ZnO films were prepared by reactive direct current (DC) magnetron sputtering at room temperature. The targets were metallic Al and Zn while the gases were Ar and O{sub 2}. X-ray diffraction (XRD) shows that the films are of hexagonal structure and Al is successfully doped into ZnO without secondary phases detected. Raman scattering spectra of the films contain the E{sub 1} mode of ZnO. Seebeck effect shows that the films are n-type and four probe instrument shows that the films are very resistive. The high resistivity is due to the compensation of acceptors such as oxygen vacancies and substitutional nitrogen atoms. The acceptors reduce the electron density and increase the work function of ZnO, which therefore weakens the field emission of Al doped ZnO films. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  18. Preparation of Al-doped ZnO films by aqueous solution process using a continuous circulation reactor

    Energy Technology Data Exchange (ETDEWEB)

    Miyake, Masao; Fukui, Hiroshi; Hirato, Tetsuji [Graduate School of Energy, Kyoto University, Yoshida-hommachi, Sakyo-ku, Kyoto 606-8501 (Japan)

    2012-05-15

    The fabrication of Al-doped ZnO films by an aqueous solution process using a continuous circulation reactor was studied. By heating ZnO-saturated ammonia solutions containing 2-10 mM Al(NO{sub 3}){sub 3} with pH 10.7 at 90 C under ambient pressure, polycrystalline ZnO films with Al content of 1-2 at.% were deposited. The carrier concentration of ZnO films increased with increasing Al content, indicating that Al was successfully incorporated into the ZnO crystals. The Al-doped ZnO films had carrier concentrations of 10{sup 19}-10{sup 20} cm{sup -3} and mobilities of 0.7-7 cm{sup 2}/V/s after annealing at 300 C in air. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  19. Structural and electrical properties of atomic layer deposited Al-doped ZnO films

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Do-Joong; Kim, Hyun-Mi; Kwon, Jang-Yeon; Choi, Hyoji [Department of Materials Science and Engineering, Seoul National University, 599 Gwanak-ro, Gwanak-gu, Seoul 151-742 (Korea, Republic of); Kim, Soo-Hyun [School of Materials Science and Engineering, Yeungnam University, Gyeongsan-si, Gyeongsangbuk-do 712-749 (Korea, Republic of); Kim, Ki-Bum [Department of Materials Science and Engineering, Seoul National University, 599 Gwanak-ro, Gwanak-gu, Seoul 151-742 (Korea, Republic of); WCU Hybrid Materials Program, Department of Materials Science and Engineering, Seoul National University, 599 Gwanak-ro, Gwanak-gu, Seoul 151-742 (Korea, Republic of)

    2011-02-08

    Structural and electrical properties of Al-doped ZnO (AZO) films deposited by atomic layer deposition (ALD) are investigated to study the extrinsic doping mechanism of a transparent conducting oxide. ALD-AZO films exhibit a unique layer-by-layer structure consisting of a ZnO matrix and Al{sub 2}O{sub 3} dopant layers, as determined by transmission electron microscopy analysis. In these layered AZO films, a single Al{sub 2}O{sub 3} dopant layer deposited during one ALD cycle could provide {approx}4.5 x 10{sup 13} cm{sup -2} free electrons to the ZnO. The effective field model for doping is suggested to explain the decrease in the carrier concentration of ALD-AZO films when the interval between the Al{sub 2}O{sub 3} layers is reduced to less than {approx}2.6 nm (>3.4 at% Al). By correlating the electrical and structural properties, an extrinsic doping mechanism of ALD-AZO films is proposed in which the incorporated Al atoms take oxygen from the ZnO matrix and form doubly charged donors, such as oxygen vacancies or zinc interstitials. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  20. Impressive enhancement in the cell performance of ZnO nanorod-based perovskite solar cells with Al-doped ZnO interfacial modification.

    Science.gov (United States)

    Dong, Juan; Zhao, Yanhong; Shi, Jiangjian; Wei, Huiyun; Xiao, Junyan; Xu, Xin; Luo, Jianheng; Xu, Jing; Li, Dongmei; Luo, Yanhong; Meng, Qingbo

    2014-11-11

    Al-doped ZnO (AZO) modified ZnO nanorods have been applied in CH3NH3PbI3 perovskite solar cells, which can show a positive effect on open circuit voltage and power conversion efficiency. The average power conversion efficiency is improved from 8.5% to 10.07% and the maximum efficiency reaches 10.7%.

  1. Fabrication of deep-profile Al-doped ZnO one- and two-dimensional lattices as plasmonic elements

    DEFF Research Database (Denmark)

    Jensen, Flemming; Shkondin, Evgeniy; Takayama, Osamu

    2016-01-01

    In this work, we report on fabrication of deep-profile one- and two-dimensional lattices made from Al-doped ZnO (AZO). AZO is considered as an alternative plasmonic material having the real part of the permittivity negative in the near infrared range. The exact position of the plasma frequency...

  2. Electrical transport and Al doping efficiency in nanoscale ZnO films prepared by atomic layer deposition

    NARCIS (Netherlands)

    Wu, Y.; Hermkens, P.M.; Loo, B.W.H. van de; Knoops, H.C.M.; Potts, S.E.; Verheijen, M.A.; Roozeboom, F.; Kessels, W.M.M.

    2013-01-01

    In this work, the structural, electrical, and optical properties as well as chemical bonding state of Al-doped ZnO films deposited by atomic layer deposition have been investigated to obtain insight into the doping and electrical transport mechanisms in the films. The range in doping levels from 0%

  3. On performance limitations and property correlations of Al-doped ZnO deposited by radio-frequency sputtering

    DEFF Research Database (Denmark)

    Crovetto, Andrea; Ottsen, Tobias Sand; Stamate, Eugen

    2016-01-01

    The electrical properties of RF-sputtered Al-doped ZnO are often spatially inhomogeneous and strongly dependent on deposition parameters. In this work, we study the mechanisms that limit the minimum resistivity achievable under different deposition regimes. In a low- and intermediate...

  4. Tunable antireflection from conformal Al-doped ZnO films on nanofaceted Si templates.

    Science.gov (United States)

    Basu, Tanmoy; Kumar, Mohit; Sahoo, Pratap Kumar; Kanjilal, Aloke; Som, Tapobrata

    2014-01-01

    Photon harvesting by reducing reflection loss is the basis of photovoltaic devices. Here, we show the efficacy of Al-doped ZnO (AZO) overlayer on ion beam-synthesized nanofaceted silicon for suppressing reflection loss. In particular, we demonstrate thickness-dependent tunable antireflection (AR) from conformally grown AZO layer, showing a systematic shift in the reflection minima from ultraviolet to visible to near-infrared ranges with increasing thickness. Tunable AR property is understood in light of depth-dependent refractive index of nanofaceted silicon and AZO overlayer. This improved AR property significantly increases the fill factor of such textured heterostructures, which reaches its maximum for 60-nm AZO compared to the ones based on planar silicon. This thickness matches with the one that shows the maximum reduction in surface reflectance. 81.07.-b; 42.79.Wc; 81.16.Rf; 81.15.Cd.

  5. Origin of carrier scattering in polycrystalline Al-doped ZnO films

    Science.gov (United States)

    Jia, Junjun; Oka, Nobuto; Kusayanagi, Minehide; Nakatomi, Satoshi; Shigesato, Yuzo

    2014-10-01

    We observed the carrier transport phenomena in polycrystalline Al-doped ZnO (AZO) films with carrier densities ranging from 2.0 × 1019 to 1.1 × 1021 cm-3. A comparison of the optical carrier density and Hall carrier density indicates that the conduction band in AZO films is nonparabolic above 2.0 × 1020 cm-3. A transition from grain boundary scattering to ionized impurity scattering is observed at a doping level of ˜4.0 × 1020 cm-3. The trap density at the grain boundary increases with increasing Al concentration in the films, implying that the doping level plays a decisive role in the trap density. The excellent fitting of the optical mobility and carrier density using the Brooks-Herring model shows that the acceptor concentration increases with increasing doping level.

  6. Structural defects and photoluminescence studies of sol-gel prepared ZnO and Al-doped ZnO films

    Science.gov (United States)

    Sandeep, K. M.; Bhat, Shreesha; Dharmaprakash, S. M.

    2016-11-01

    ZnO and Al-doped ZnO (AZO) films were synthesized using sol-gel spin-coating method. The powder XRD analysis revealed the stress relaxation mechanism upon Al doping in ZnO film. The reduction in the imaginary part of the dielectric constant and suppression of deep level acceptor type octahedral oxygen interstitial defects account for the reduction in carrier concentration in AZO with respect to ZnO. Electrical conductivity measurements and grain boundary conduction model are used to quantify the carrier concentration. From the Commission Internationale d'Eclairge diagram of ZnO and AZO, color parameters like dominant wavelength, color purity and luminosity are determined and reported for the first time. The prepared ZnO and AZO films show considerable blue emission. These films can be used for white light generation.

  7. Room-temperature violet luminescence and ultraviolet photodetection of Sb-doped ZnO/Al-doped ZnO homojunction array.

    Science.gov (United States)

    Chen, Wei-Jen; Wu, Jen-Kai; Lin, Jheng-Cyuan; Lo, Shun-Tsung; Lin, Huang-De; Hang, Da-Ren; Shih, Ming Feng; Liang, Chi-Te; Chang, Yuan Huei

    2013-07-05

    A Sb-doped ZnO microrod array was fabricated on an Al-doped ZnO thin film by electrodeposition. Strong violet luminescence, originated from free electron-to-acceptor level transitions, was identified by temperature-dependent photoluminescence measurements. This acceptor-related transition was attributed to substitution of Sb dopants for Zn sites, instead of O sites, to form a complex with two Zn vacancies (VZn), the SbZn-2VZn complex. This SbZn-2VZn complex has a lower formation energy and acts as a shallow acceptor which can induce the observed strong violet luminescence. The photoresponsivity of our ZnO p-n homojunction device under a negative bias demonstrated a nearly 40-fold current gain, illustrating that our device is potentially an excellent candidate for photodetector applications in the ultraviolet wavelength region.

  8. Optical and electrical properties of hydrothermally grown Al-doped ZnO nanorods on graphene/Ni/Si substrate

    Science.gov (United States)

    Wang, L. L.; Lin, B. Z.; Hung, M. P.; Zhou, L.; Panin, G. N.; Kang, T. W.; Fu, D. J.

    2013-04-01

    We present a simple way to prepare low-resistance ZnO nanorods by hydrothermal self-assembled growth at 95 °C and in situ doped with Al. The NRs were grown on graphene/Ni/Si and annealed at 400 °C. Few layer graphene was used to assist aligned growth of the NRs and acted as an electrode during electric measurement. The measurement showed resistance of the Al-doped ZnO NRs 100 times lower than that of undoped ZnO NRs. Photoluminescence measurement showed enhanced deep level emission for the Al-doped NRs and low temperature photoluminescence study showed coexistence of acceptor bound-exciton (3.353 eV) and donor bound-exciton (3.362 eV).

  9. Fabrication of Al doped ZnO films using atmospheric pressure cold plasma

    Energy Technology Data Exchange (ETDEWEB)

    Suzaki, Yoshifumi, E-mail: suzaki@eng.kagawa-u.ac.jp [Faculty of Engineering, Kagawa University, Hayashi-cho 2217-20, Takamatsu, Kagawa 761-0396 (Japan); Miyagawa, Hayato; Yamaguchi, Kenzo [Faculty of Engineering, Kagawa University, Hayashi-cho 2217-20, Takamatsu, Kagawa 761-0396 (Japan); Kim, Yoon-Kee [Dept. of Welding and Production Engineering, Hanbat National University, San 16-1, Duckmyoung-dong, Yuseong-gu, Daejeon 305-719 (Korea, Republic of)

    2012-11-01

    Under atmospheric pressure, homogeneous non-equilibrium cold plasma was generated stably by high voltage pulsed power (1 kV, 20 kHz, 38 W) excitation of a mixture of He and O{sub 2} gases produced by a dielectric barrier discharge setup. By feeding Bis (2 methoxy-6-methyl-3, 5-heptanedione) Zn (Zn-MOPD, C{sub 18}H{sub 3}O{sub 6}Zn) and Tris (2-methoxy-6-methy l-3, 5-heptanedione) Al (Al-MOPD, C{sub 27}H{sub 45}O{sub 9}Al) into this plasma with He carrier gas, transparent flat Al-doped ZnO (ZnO:Al) films about 120-240 nm thick were prepared on glass substrates directly under the slit made into the cathode. Deposition rates of the films were about 20-40 nm/min. The concentration of Al was measured by inductively coupled plasma atomic emission spectroscopy. The composition ratio of Al to Zn was 7.8 mol% when the carrier He gas flow rate of Al-MOPD was 30 cm{sup 3}. The average transmittance of all films was more than 85% in the wavelength range from 400 to 800 nm. When the composition ratio of Al/Zn was between 1.1 and 7.8 mol%, the optical band gap of the film increased from 3.28 to 3.40 eV. The resistivity of ZnO:Al film was 2.96 {Omega} cm at 1.3 mol% of Al/Zn. In addition, the microstructure of the films was studied by X-ray diffraction measurement and field emission scanning electron microscope observation. It was revealed that doped Al is substituted onto the Zn site of the ZnO crystalline structure in ZnO:Al films. - Highlights: Black-Right-Pointing-Pointer An atmospheric pressure cold plasma generator generated stable glow discharge. Black-Right-Pointing-Pointer We fabricated Al doped ZnO films on glass substrates using cold plasma. Black-Right-Pointing-Pointer Al concentration measured by inductively coupled plasma atomic emission spectroscopy. Black-Right-Pointing-Pointer The transmission spectrum and the resistivity of the films were measured. Black-Right-Pointing-Pointer The microstructure of the films was studied.

  10. New approach towards an optimized light trapping morphology of Al-doped ZnO films

    Energy Technology Data Exchange (ETDEWEB)

    Sittinger, V.; Dewald, W.; Szyszka, B. [Fraunhofer Institute for Surface Engineering and Thin Films IST, Braunschweig (Germany); Saeuberlich, F. [Schmid Technology Center, Dunningen (Germany); Stannowski, B. [Competence Centre Thin-Film- and Nanotechnology for Photovoltaics Berlin (Germany)

    2011-04-15

    Throughout the last years strong efforts have been make to use Al-doped ZnO films on glass as substrates for amorphous or amorphous/microcrystalline silicon solar cells. The material promises better performance at low cost especially because ZnO:Al can be roughened in order to enhance the light scattering into the cell. Best optical and electrical properties are usually achieved by RF sputtering of ceramic targets. Aluminium doped ZnO films were deposited dynamically by DC magnetron sputtering from a ceramic ZnO:Al{sub 2}O{sub 3} target (1 wt.%) onto an additional seed layer. The process parameters, namely oxygen partial pressure, total pressure and temperature were kept constant, only the seed layer thickness was varied. ZnO:Al{sub 2}O{sub 3} films are investigated in respect of optical, electrical properties and etch enhanced morphology for a-Si:H/{mu}c-Si:H solar cells. Additionally the etch morphology was examined by SEM. The seed layer allows getting an optimized light trapping morphology after the hydrochloric etching which shows nearly the same as a pure RF sputtered film. (orig.)

  11. Complex hierarchical arrangements of stacked nanoplates in Al-doped ZnO

    Energy Technology Data Exchange (ETDEWEB)

    Ortega, Y. [Departamento de Fisica de Materiales, Facultad de Ciencias Fisicas, Universidad Complutense de Madrid, 28040 Madrid (Spain); Mikrostrukturanalytik, Christian-Albrechts Universitaet zu Kiel, 24143 Kiel (Germany); Haeussler, D.; Jaeger, W. [Mikrostrukturanalytik, Christian-Albrechts Universitaet zu Kiel, 24143 Kiel (Germany); Piqueras, J.; Fernandez, P. [Departamento de Fisica de Materiales, Facultad de Ciencias Fisicas, Universidad Complutense de Madrid, 28040 Madrid (Spain)

    2012-08-15

    Al-doped micro- and nanostructures have been grown by an evaporation-deposition method with a mixture of ZnS and Al{sub 2}O{sub 3} powders as precursor. It has been found that the presence of Al is the cause of the growth of complex morphologies, as rods formed by stacks of nanoplates and other complex hierarchical structures. The role of Al in the growth process has been investigated by electron microscopy techniques. Al-rich particles in specific sites of a central rod lead to hierarchical growth. Transmission electron microscopy shows that in some cases the Al-rich zones are clusters of spinel ZnAl{sub 2}O{sub 4} nanoparticles adhered to ZnO nanorods. Al incorporation into the structures and the dopant effect on the luminescence behavior of the ZnO structures were investigated by energy dispersive spectroscopy and by cathodoluminescence. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  12. Influence of annealing atmosphere on optical properties of Al-doped ZnO powders

    Energy Technology Data Exchange (ETDEWEB)

    Li, Chundong; Lv, Jinpeng; Zhou, Bo; Liang, Zhiqiang [Key Laboratory on Materials Behaviour and Evaluation Technology in Space Environment, School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China)

    2012-08-15

    We systematically studied the influences of annealing atmosphere on the structural and optical properties of Al-doped ZnO (AZO) powders by performing anneals in N{sub 2}, Ar{sub 2}, H{sub 2} and O{sub 2} atmospheres. The results indicated that the optical properties were highly influenced by the annealing atmosphere, which were more pronounced for the AZO powders annealed in forming gas and an oxygen atmosphere. The E{sub 1} (LO) vibration mode in the Raman spectra exhibits a good correlation with the green emission and is demonstrated to be originated from V{sub O} defects. We conclude that both V{sub O} and O{sub i} defects give rise to the green photoluminescence in ZnO, and each will play a dominant role in oxygen-deficient and oxygen-rich environments, respectively. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  13. Growth and properties of electrodeposited transparent Al-doped ZnO nanostructures

    Science.gov (United States)

    Baka, O.; Mentar, L.; Khelladi, M. R.; Azizi, A.

    2015-12-01

    Al-doped zinc oxide (AZO) nanostructures were fabricated on fluorine-doped tin-oxide (FTO)- coated glass substrates by using electrodeposition. The effects of the doping concentration of Al on the morphological, microstructural, electrical and optical properties of the nanostructures were investigated. From the field emission scanning electron microscopy (FE-SEM) observation, when the amount of Al was increased in the solution, the grains size was observed to decreases. The observed changes in the morphology indicate that Al acts as nucleation centers in the vacancy sites of ZnO and destroys the crystalline structure at high doping level. Effectively, the X-ray diffraction (XRD) analysis indicated that the undoped and the doped ZnO nanostructures has a polycrystalline nature and a hexagonal wurtzite structure with a (002) preferential orientation. The photoluminescence (PL) room-temperature measurements showed that the incorporation of Al in the Zn lattice can improve the intensity of ultraviolet (UV) emission, thus suggesting its greater prospects for use in UV optoelectronic devices.

  14. A first-principles study on Al-doped ZnO growth polarity on sapphire (0001) surface

    Science.gov (United States)

    Yang, Ping; Gao, Qian; Hu, Zhen-Peng; Zhang, Li-Xin

    2016-06-01

    Based on the first-principles method, the polarity inversion mechanism of Al-doped ZnO grown on sapphire (0001) substrate was investigated. This study revealed that the Al dopant tends to float on the surface of the buffer layer and leads to form ZnO nucleation islands of Zn-polarity without changing in-plane orientation. Finally, these islands evolve to wall-like nanostructure with Zn-termination. The results can explain the reason of the polarity inversion phenomenon in the experiment and supply more information for controlling the ZnO growth polarity.

  15. Structural and luminescence properties of pure and Al-doped ZnO nanopowders

    Energy Technology Data Exchange (ETDEWEB)

    Louiza, Arab; Saliha, Hamdelou; Sofiane, Harouni [Laboratory of Physics-Chemistry of Semiconductors, Department of Physics, University Mentouri, Constantine 25000 (Algeria); Kamel, Guergouri, E-mail: kamelguergouri@yahoo.com [Laboratory of Physics-Chemistry of Semiconductors, Department of Physics, University Mentouri, Constantine 25000 (Algeria); Lakhder, Guerbous [Algiers Nuclear Research Center, Algiers 16000 (Algeria)

    2012-06-25

    Highlights: Black-Right-Pointing-Pointer The powders follow the wuertzite structure and possess a very small size. Black-Right-Pointing-Pointer The grain size deceases as a function of Al concentration. Black-Right-Pointing-Pointer The powders' morphology evaluates with increasing Al concentration from pebbles without cavities to highly porous powder. Black-Right-Pointing-Pointer The blue luminescence peaks of the PL spectrum covering the green to the ultraviolet area are the most intense. Black-Right-Pointing-Pointer The violet luminescence intensity decreases with increasing Al concentration. - Abstract: Pure and Al doped zinc oxide nanopowders have been synthesized by sol-gel route. This is a simple and inexpensive method permitting to obtain a very small grain size powders. Zinc acetate dehydrate was first dissolved in a mixture of 2-methoxyethanol and mono-ethanolamine (MEA) solution, were used as a solvent and stabilizer respectively and doped with a quantity of aluminum nitrate, varying from 0 to 10 mol%. The obtained gel is then calcinated in air at 500 Degree-Sign C. The samples are characterized by XRD, SEM and photoluminescence (PL) studies. The XRD results indicate that pure and Al-doped ZnO powders are solid solutions crystallizing in pure wuertzite structure, and consisted of a mixture of nanoparticles with grain size between 23 and 36 nm. The grain size decreases strongly with increasing Al concentration and reaches its lowest value at 5 mol% Al. The PL spectra show that the most important establishment is that the powders show luminescence peaks from green to ultraviolet light, and thus can be used to manufacture transmitters using these emissions. The peaks connected to the blue luminescence are the most intense, and they are generated by transitions involving (Zn{sub i}). The SEM images show a formation of pebbles with sizes decreasing with Al concentration and a morphology evaluating, qualitatively, from pebbles without cavities to highly

  16. Al-doped ZnO seed layer-dependent crystallographic control of ZnO nanorods by using electrochemical deposition

    Energy Technology Data Exchange (ETDEWEB)

    Son, Hyo-Soo; Choi, Nak-Jung [Department of Nano-Optical Engineering, Korea Polytechnic University, Siheung 429-793 (Korea, Republic of); Kim, Kyoung-Bo [Department of Metallurgical and Materials Engineering, Inha Technical College, Incheon 402-752 (Korea, Republic of); Kim, Moojin [Department of Renewable Energy, Jungwon University, Goesan-gun, Chungbuk 367-805 (Korea, Republic of); Lee, Sung-Nam, E-mail: snlee@kpu.ac.kr [Department of Nano-Optical Engineering, Korea Polytechnic University, Siheung 429-793 (Korea, Republic of)

    2016-10-15

    Highlights: • Polar and semipolar ZnO NRs were successfully achieved by hydrothermal synthesis. • Semipolar and polar ZnO NRs were grown on ZnO and AZO/m-sapphire, respectively. • Al % of AZO/m-sapphire enhanced the lateral growth rate of polar ZnO NRs. - Abstract: We investigated the effect of an Al-doped ZnO film on the crystallographic direction of ZnO nanorods (NRs) using electrochemical deposition. From high-solution X-ray diffraction measurements, the crystallographic plane of ZnO NRs grown on (1 0 0) ZnO/m-plane sapphire was (1 0 1). The surface grain size of the (100) Al-doped ZnO (AZO) film decreased with increasing Al content in the ZnO seed layer, implying that the Al dopant accelerated the three-dimensional (3D) growth of the AZO film. In addition, it was found that with increasing Al doping concentration of the AZO seed layer, the crystal orientation of the ZnO NRs grown on the AZO seed layer changed from [1 0 1] to [0 0 1]. With increasing Al content of the nonpolar (1 0 0) AZO seed layer, the small surface grains with a few crystallographic planes of the AZO film changed from semipolar (1 0 1) ZnO NRs to polar (0 0 1) ZnO NRs due to the increase of the vertical [0 0 1] growth rate of the ZnO NRs owing to excellent electrical properties.

  17. Comparison of two innovative precipitation systems for ZnO and Al-doped ZnO nanoparticle synthesis

    Directory of Open Access Journals (Sweden)

    Anne Aimable

    2010-09-01

    Full Text Available This study presents a comparative approach to investigate the potentials of two innovative methods for the synthesis of ZnO and Al-doped ZnO. The first method is a precipitation system working in mild hydrothermal conditions (90°C using a tubular reactor (Segmented Flow Tubular Reactor, SFTR. The second method is a microwave-assisted hydrothermal process working at 250°C - 38 atmospheres. Nanocrystalline ZnO with a high specific surface area (49–68 m2/g was obtained with both systems. Smaller equiaxed particles (50–70 nm were obtained with the SFTR, with an excellent homogeneity in size and morphology, which was attributed to an excellent control of the process parameters (mixing, temperature, volume of reaction. A higher luminescence signal was measured on these samples. The microwave method leads to particles with a higher crystallinity due to the temperature of the reaction. A significant effect of the aluminum was observed, which reduces the crystal growth to produce equiaxed morphologies. This effect was enhanced by adding poly(acrylic acid (PAA.

  18. Temperature-dependence on the structural, optical, and magnetic properties of Al-doped ZnO nanoparticles

    Science.gov (United States)

    Lu, Xiaofei; Liu, Yongsheng; Si, Xiaodong; Shen, Yulong; Yu, Wenying; Wang, Wenli; Luo, Xiaojing; Zhou, Tao

    2016-12-01

    Al-doped ZnO nanoparticles synthesized by a hydrothermal method at relatively low temperature synthesis and anneal were reported in this paper. The XRD results reveal that all the samples have a hexagonal wurtzite structure. A higher synthesis temperature leads to a slight increase in the grain size and improvement of the crystal quality. Different morphologies evolved from acicular closely-packed morphology to dandelion-like 3D nanostructures can be obtained by controlling the synthesis temperatures. Moreover, the influence of synthesis temperature on optical property indicates that the absorption ability in ultraviolet region declines with increasing the synthesis temperature. In addition, the annealed nanoparticles have an enhancement of the room temperature ferromagnetism (RT-FM) and the saturation magnetization (MS). Those results suggest that Al-doped ZnO nanoparticles synthesized at relatively low temperature could be a promising candidate for photosensitive and room temperature nanolasers applications.

  19. Solution processed Al-doped ZnO nanoparticles/TiOx composite for highly efficient inverted organic solar cells.

    Science.gov (United States)

    Gadisa, Abay; Hairfield, Travis; Alibabaei, Leila; Donley, Carrie L; Samulski, Edward T; Lopez, Rene

    2013-09-11

    We investigated the electrical properties of solution processed Al-doped ZnO (AZO) nanoparticles, stabilized by mixing with a TiOx complex. Thin solid films cast from the solution of AZO-TiOx (AZOTi) (Ti/Zn ∼0.4 in the bulk and ∼0.8 on its surface) is processable in inert environment, without a need for either ambient air exposure for hydrolysis or high temperature thermal annealing commonly applied to buffer layers of most metal-oxides. It was found that the electronic structure of AZOTi matches the electronic structure of several electron acceptor and donor materials used in organic electronic devices, such as solar cells. Inverted solar cells employing a bulk heterojunction film of poly(3-hexylthiophene) and phenyl-C61-butyric acid methyl ester, cast on an indium-tin-oxide/AZOTi electrode, and capped with a tungsten oxide/aluminum back electrode, give rise to a nearly 70% fill factor and an optimized open-circuit voltage as a result of efficient hole blocking behavior of AZOTi. The resulting electron collecting/blocking capability of this material solves crucial interfacial recombination issues commonly observed at the organic/metal-oxide interface in most inverted organic bulk heterojunction solar cells.

  20. Near-infrared reflection from Al-doped ZnO films prepared by multi-target reactive sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Okuhara, Y; Matsubara, H [Japan Fine Ceramics Center, 2-4-1 Mutsuno, Atsuta-ku, Nagoya, Aichi 456-8587 (Japan); Takata, M, E-mail: okuhara@jfcc.or.jp [Nagaoka University of Technology, Kamitomioka 1603-1, Nagaoka, Niigata 940-2188 (Japan)

    2011-10-29

    Thin films of aluminium-doped zinc oxide (ZnO:Al) as heat reflective coatings were prepared by multi-target reactive sputtering using metallic Zn and Al targets. An optimization of Al content and a reduction in oxygen partial pressure were crucial in increasing the carrier concentration N{sub e} and the Hall mobility {mu}. The ZnO:Al film with the highest N{sub e} achieved the shortest plasma wavelength {lambda}{sub p} of 1375 nm, which shifted the near-infrared reflectance spectrum closer to the visible region. The high {mu} reduced the optical absorption and enhanced the reflectance. Moreover, the multi-target system enabled intermittent doping of Al, which was applied to stack multilayers consisting of non-doped and Al-doped ZnO layers. A drop in the refractive indices n above {lambda}{sub p} for the ZnO:Al layers formed the periodic distribution of n in the thickness direction, which provided a high reflectance zone from 1000 to 1400 nm in wavelength.

  1. Effects of ITO precursor thickness on transparent conductive Al doped ZnO film for solar cell applications

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Dong-Won; Kuk, Seung-Hee; Han, Min-Koo [School of Electrical Engineering, Seoul National University, Gwanak-gu, Seoul 151-742 (Korea, Republic of); Ji, Kwang-Sun; Lee, Heon-Min [LG Electronics, 16 Woomyeon-Dong Seocho-Gu, Seoul (Korea, Republic of)

    2011-01-15

    Al doped ZnO (AZO) film was continuously deposited on ITO precursor on glass substrate by d.c. magnetron sputtering. The thickness of ITO was varied from 30 to 120 nm in order to investigate the effect of ITO thickness on crystallinity of AZO film. X-ray diffraction measurement shows that AZO film grown on ITO has an enhanced (0 0 2) preferred orientation as the ITO thickness was increased. The crystalline structure improvement of AZO film with an increase of ITO precursor thickness is due to the near-epitaxial growth of AZO on ITO precursor. As the ITO thickness was increased, mobility of AZO film by the Hall measurement was significantly increased from 5.4 cm{sup 2}/V s (no ITO) to 23.6 cm{sup 2}/V s (ITO 120 nm), and resistivity was about 81.7% improved from 1.99 x 10{sup -3} to 3.63 x 10{sup -4} {omega} cm. The AZO films with ITO revealed excellent average transmission of visible (90.0%) and NIR (89.6%) regions, whereas those of AZO film without ITO were 82.1% and 88.1%, respectively. The haze values of AZO film with ITO of 90 and 120 nm are similar or higher than those of AZO film without ITO. The surface textured AZO film with ITO precursor is promising for optoelectronic applications such as the front TCO of thin film solar cells. (author)

  2. Electromechanical and Photoluminescence Properties of Al-doped ZnO Nanorods Applied in Piezoelectric Nanogenerators

    Science.gov (United States)

    Chang, Wen-Yang; Fang, Te-Hua; Tsai, Ju-Hsuan

    2015-02-01

    A piezoelectric nanogenerator based on Al-doped ZnO (AZO) nanorods with a V-zigzag layer is investigated at a low temperature. The growth temperature, growth time, growth concentration, photoluminescence (PL) spectrum, and AZO epitaxial growth on the ITO glass substrate using aqueous solution are reported and the associated electromechanical and PL properties are discussed. In general, the properties of piezoelectric nanogenerators and their functionality at ultralow temperatures (near liquid helium temperature) are important for applications in extreme environments. A V-zigzag layer is used to enhance the bending and compression deformation of the piezoelectric nanogenerator. The electromechanical properties of AZO nanorods are tested using an ultrasonic wave generator. Results show that the percent transmittance decreases with increasing growth time and growth temperature. The intensities of the PL spectrum and the (002) peak orientation increases with increasing growth temperature. AZO at a low growth temperature of 90 C has good piezoelectric harvesting efficiency when the piezoelectric nanogenerator has a zigzag structure. The average current, voltage, and power density of the piezoelectric harvesting are 0.76 A, 1.35 mV, and 1.026 nW/mm, respectively. These results confirm the feasibility of growing AZO at low temperature. AZO nanorods have potential for energy harvester applications.

  3. Effects of annealing pressure and Ar+ sputtering cleaning on Al-doped ZnO films

    Science.gov (United States)

    Wang, Jiwei; Mei, Yong; Lu, Xuemei; Fan, Xiaoxing; Kang, Dawei; Xu, Panfeng; Tan, Tianya

    2016-11-01

    Post-treatments of Al-doped ZnO films fabricated by sol-gel method were studied in condition of annealing in air, vacuum and protective ambient, as well as the follow-up Ar+ sputtering cleaning. The effect of annealing pressure on resistivity of AZO films was investigated from 105 to 10-4 Pa, where the resistivity decreased four orders of magnitude as the pressure decreased and approached to its minimum at 10 Pa. It was observed that the main decreasing of resistivity occurred in a very narrow range of middle vacuum (between 100 and 10 Pa) and high vacuum was dispensable. The XRD and XPS characterizations demonstrated that the radical increasing of oxygen vacancy, Zn interstitial and substitution of Al3+ for Zn2+ under middle vacuum were responsible for the significant enhancement of conductivity. The follow-up Ar+ sputtering cleaning can further decrease the resistivity through removing the chemisorbed oxygen on film surface and grain boundaries, meanwhile fulfil the surface texture process, and thus improve both electrical and optical performances for applications.

  4. CdS nanoparticles sensitization of Al-doped ZnO nanorod array thin film with hydrogen treatment as an ITO/FTO-free photoanode for solar water splitting

    National Research Council Canada - National Science Library

    Hsu, Chih-Hsiung; Chen, Dong-Hwang

    2012-01-01

    Aluminum-doped zinc oxide (AZO) nanorod array thin film with hydrogen treatment possesses the functions of transparent conducting oxide thin film and 1-D nanostructured semiconductor simultaneously...

  5. Growth and optical properties of ZnO nanorod arrays on Al-doped ZnO transparent conductive film.

    Science.gov (United States)

    Lin, Suanzhi; Hu, Hailong; Zheng, Weifeng; Qu, Yan; Lai, Fachun

    2013-04-08

    ZnO nanorod arrays (NRAs) on transparent conductive oxide (TCO) films have been grown by a solution-free, catalyst-free, vapor-phase synthesis method at 600°C. TCO films, Al-doped ZnO films, were deposited on quartz substrates by magnetron sputtering. In order to study the effect of the growth duration on the morphological and optical properties of NRAs, the growth duration was changed from 3 to 12 min. The results show that the electrical performance of the TCO films does not degrade after the growth of NRAs and the nanorods are highly crystalline. As the growth duration increases from 3 to 8 min, the diffuse transmittance of the samples decreases, while the total transmittance and UV emission enhance. Two possible nanorod self-attraction models were proposed to interpret the phenomena in the sample with 9-min growth duration. The sample with 8-min growth duration has the highest total transmittance of 87.0%, proper density about 75 μm-2, diameter about 26 nm, and length about 500 nm, indicating that it can be used in hybrid solar cells.

  6. Effect of Al doping on phase formation and thermal stability of iron nitride thin films

    Energy Technology Data Exchange (ETDEWEB)

    Tayal, Akhil [Amity Center for Spintronic Materials, Amity University, Sector 125, Noida 201 303 (India); Gupta, Mukul, E-mail: mgupta@csr.res.in [Amity Center for Spintronic Materials, Amity University, Sector 125, Noida 201 303 (India); Pandey, Nidhi [Amity Center for Spintronic Materials, Amity University, Sector 125, Noida 201 303 (India); Gupta, Ajay [UGC-DAE Consortium for Scientific Research, University Campus, Khandwa Road, Indore 452 001 (India); Horisberger, Michael [Laboratory for Developments and Methods, Paul Scherrer Institut, CH-5232 Villigen PSI (Switzerland); Stahn, Jochen [Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institut, CH-5232 Villigen PSI (Switzerland)

    2015-11-25

    In the present work, we systematically studied the effect of Al doping on the phase formation of iron nitride (Fe–N) thin films. Fe–N thin films with different concentration of Al (Al = 0, 2, 3, 6, and 12 at.%) were deposited using dc magnetron sputtering by varying the nitrogen partial pressure between 0 and 100%. The structural and magnetic properties of the films were studied using x-ray diffraction and polarized neutron reflectivity. It was observed that at the lowest doping level (2 at.% of Al), nitrogen rich non-magnetic Fe–N phase gets formed at a lower nitrogen partial pressure as compared to the un-doped sample. Interestingly, we observed that as Al doping is increased beyond 3 at.%, nitrogen rich non-magnetic Fe–N phase appears at higher nitrogen partial pressure as compared to un-doped sample. The thermal stability of films were also investigated. Un-doped Fe–N films deposited at 10% nitrogen partial pressure possess poor thermal stability. Doping of Al at 2 at.% improves it marginally, whereas, for 3, 6 and 12 at.% Al doping, it shows significant improvement. The obtained results have been explained in terms of thermodynamics of Fe–N and Al–N. - Highlights: • Doping effects of Al on Fe–N phase formation is studied. • Phase formation shows a non-monotonic behavior with Al doping. • Low doping levels of Al enhance and high levels retard the nitridation process. • Al doping beyond 3 at.% improve thermal stability of Fe–N films.

  7. Transmission electron microscopy of solution-processed, intrinsic and Al-doped ZnO nanowires for transparent electrode fabrication.

    Science.gov (United States)

    Kusinski, G J; Jokisaari, J R; Noriega, R; Goris, L; Donovan, M; Salleo, A

    2010-03-01

    A solution-based chemistry was used to synthesize intrinsic and Al-doped (1% and 5% nominal atomic concentration of Al) ZnO nanostructures. The nanowires were grown at 300 degrees C in trioctylamine by dissolving Zn acetate and Al acetate. Different doping conditions gave rise to different nanoscale morphologies. The effect of a surfactant (oleic acid) was also investigated. An electron microscopy study correlating morphology, aspect ratio and doping of the individual ZnO wires to the electrical properties of the spin coated films is presented. HRTEM revealed single crystalline [0001] wires.

  8. Enhanced Photoluminescence and Raman Properties of Al-Doped ZnO Nanostructures Prepared Using Thermal Chemical Vapor Deposition of Methanol Assisted with Heated Brass

    Science.gov (United States)

    Thandavan, Tamil Many K.; Gani, Siti Meriam Abdul; San Wong, Chiow; Md. Nor, Roslan

    2015-01-01

    Vapor phase transport (VPT) assisted by mixture of methanol and acetone via thermal evaporation of brass (CuZn) was used to prepare un-doped and Al-doped zinc oxide (ZnO) nanostructures (NSs). The structure and morphology were characterized by field emission scanning electron microscopy (FESEM) and x-ray diffraction (XRD). Photoluminescence (PL) properties of un-doped and Al-doped ZnO showed significant changes in the optical properties providing evidence for several types of defects such as zinc interstitials (Zni), oxygen interstitials (Oi), zinc vacancy (Vzn), singly charged zinc vacancy (VZn-), oxygen vacancy (Vo), singly charged oxygen vacancy (Vo+) and oxygen anti-site defects (OZn) in the grown NSs. The Al-doped ZnO NSs have exhibited shifted PL peaks at near band edge (NBE) and red luminescence compared to the un-doped ZnO. The Raman scattering results provided evidence of Al doping into the ZnO NSs due to peak shift from 145 cm-1 to an anomalous peak at 138 cm-1. Presence of enhanced Raman signal at around 274 and 743 cm-1 further confirmed Al in ZnO NSs. The enhanced D and G band in all Al-doped ZnO NSs shows possible functionalization and doping process in ZnO NSs. PMID:25756598

  9. Enhanced photoluminescence and Raman properties of Al-Doped ZnO nanostructures prepared using thermal chemical vapor deposition of methanol assisted with heated brass.

    Directory of Open Access Journals (Sweden)

    Tamil Many K Thandavan

    Full Text Available Vapor phase transport (VPT assisted by mixture of methanol and acetone via thermal evaporation of brass (CuZn was used to prepare un-doped and Al-doped zinc oxide (ZnO nanostructures (NSs. The structure and morphology were characterized by field emission scanning electron microscopy (FESEM and x-ray diffraction (XRD. Photoluminescence (PL properties of un-doped and Al-doped ZnO showed significant changes in the optical properties providing evidence for several types of defects such as zinc interstitials (Zni, oxygen interstitials (Oi, zinc vacancy (Vzn, singly charged zinc vacancy (VZn-, oxygen vacancy (Vo, singly charged oxygen vacancy (Vo+ and oxygen anti-site defects (OZn in the grown NSs. The Al-doped ZnO NSs have exhibited shifted PL peaks at near band edge (NBE and red luminescence compared to the un-doped ZnO. The Raman scattering results provided evidence of Al doping into the ZnO NSs due to peak shift from 145 cm-1 to an anomalous peak at 138 cm-1. Presence of enhanced Raman signal at around 274 and 743 cm-1 further confirmed Al in ZnO NSs. The enhanced D and G band in all Al-doped ZnO NSs shows possible functionalization and doping process in ZnO NSs.

  10. Enhanced photoluminescence and Raman properties of Al-Doped ZnO nanostructures prepared using thermal chemical vapor deposition of methanol assisted with heated brass.

    Science.gov (United States)

    Thandavan, Tamil Many K; Gani, Siti Meriam Abdul; San Wong, Chiow; Md Nor, Roslan

    2015-01-01

    Vapor phase transport (VPT) assisted by mixture of methanol and acetone via thermal evaporation of brass (CuZn) was used to prepare un-doped and Al-doped zinc oxide (ZnO) nanostructures (NSs). The structure and morphology were characterized by field emission scanning electron microscopy (FESEM) and x-ray diffraction (XRD). Photoluminescence (PL) properties of un-doped and Al-doped ZnO showed significant changes in the optical properties providing evidence for several types of defects such as zinc interstitials (Zni), oxygen interstitials (Oi), zinc vacancy (Vzn), singly charged zinc vacancy (VZn-), oxygen vacancy (Vo), singly charged oxygen vacancy (Vo+) and oxygen anti-site defects (OZn) in the grown NSs. The Al-doped ZnO NSs have exhibited shifted PL peaks at near band edge (NBE) and red luminescence compared to the un-doped ZnO. The Raman scattering results provided evidence of Al doping into the ZnO NSs due to peak shift from 145 cm-1 to an anomalous peak at 138 cm-1. Presence of enhanced Raman signal at around 274 and 743 cm-1 further confirmed Al in ZnO NSs. The enhanced D and G band in all Al-doped ZnO NSs shows possible functionalization and doping process in ZnO NSs.

  11. A Study of Structural and Photoluminescence for Al-Doped CdO Thin Films

    Directory of Open Access Journals (Sweden)

    Bong Ju Lee

    2016-01-01

    Full Text Available Al-doped CdO thin films were prepared by radio frequency magnetron sputtering at different deposition time and substrate temperature. X-ray diffraction showed that the changes in the intensities of the (200, (220, and (311 planes followed a similar trend with increase in deposition time. The surface of the thin film was examined by scanning electron microscopy. Grain sizes of Al-doped CdO thin films increased significantly with increasing deposition time. The film thicknesses were 0.09, 0.12, 0.20, and 0.225 μm for the deposition times of 1, 2, 3, and 4 h, respectively. The photoluminescence spectra of the Al-doped CdO thin films were measured at room temperature. The photoluminescence wavelength changed in the sequence, green, blue, green, and blue, with increasing deposition time, which indicates that blue light emitting films can be fabricated by adjusting the processing parameters.

  12. Effect of seed layer on the self assembly of spray pyrolyzed Al-doped ZnO nanoparticles

    Directory of Open Access Journals (Sweden)

    Charu Dwivedi

    2013-03-01

    Full Text Available Al-doped ZnO (AlZO nanorod arrays and nanostructures were fabricated on seed coated glass substrates via CoSP (Continuous Spray Pyrolysis reactor. The as-synthesized aluminium doped ZnO nanoparticles and nanorods were analyzed through different characterization techniques. There were no significant changes found in the structure with doping of Al but the morphology of the film changed to branched nanorods and nanosheets with the change in seed solution and annealing temperature, respectively. Also, the current–voltage curves of the ZnO and AZO nanorod arrays was measured and it was found that the current response of AZO nanorods was higher than that of ZnO nanorods, proving the Al incorporation as a dopant.

  13. Resistive switching characteristics of a compact ZnO nanorod array grown directly on an Al-doped ZnO substrate

    Science.gov (United States)

    Yoo, E. J.; Shin, J. Y.; Yoon, T. S.; Kang, C. J.; Choi, Y. J.

    2016-07-01

    ZnO’s resistive switching properties have drawn much attention because ZnO has a simple chemical composition and is easy to manipulate. The propulsion mechanism for resistive switching in ZnO is based on a conducting filament that consists of oxygen vacancies. In the case of film structure, the random formation of the conducting filaments occasionally leads to unstable switching characteristics. Limiting the direction in which the conducting filaments are formed is one way to solve this problem. In this study, we demonstrate reliable resistive switching behavior in a device with an Au/compact ZnO nanorod array/Al-doped ZnO structure with stable resistive switching over 105 cycles and a long retention time of 104 s by confining conducting filaments along the boundaries between ZnO nanorods. The restrictive formation of conducting filaments along the boundaries between ZnO nanorods is observed directly using conductive atomic force microscopy.

  14. Influence of excitation wavelength on photoluminescence spectra of Al doped ZnO films

    Energy Technology Data Exchange (ETDEWEB)

    Khan, Firoz; Ameen, Sadia; Song, Minwu [Energy Materials and Surface Science Laboratory, Solar Energy Research Center, School of Chemical Engineering, Chonbuk National University, Jeonju 561-756 (Korea, Republic of); Shik Shin, Hyung, E-mail: hsshin@jbnu.ac.kr [Energy Materials and Surface Science Laboratory, Solar Energy Research Center, School of Chemical Engineering, Chonbuk National University, Jeonju 561-756 (Korea, Republic of)

    2013-02-15

    Dependence of photoluminescence (PL) spectra of Al doped zinc oxide (AZO) films in near band edge (NBE) and green regions on the excitation wavelength ({lambda}{sub ex}) has been investigated. A redshift has been observed in both the regions with increase of {lambda}{sub ex}. The redshift of free exciton emission (FX) peaks with increase of {lambda}{sub ex} may be due to different contributions of excitonic emissions and their phonon replicas. The intensity of these peaks decreases exponentially with increase of {lambda}{sub ex}. The peaks related to first order transverse optical longitudinal optical replicas of the FX (FX-TO-1LO) phonon replica disappeared beyond {lambda}{sub ex}=220 nm. The peaks assigned to FX{sub A}{sup n=1} and FX{sub A}{sup n=2} become visible for {lambda}{sub ex}{>=}340 nm and become stronger for {lambda}{sub ex}=360 nm. The separation between the two consecutive phonon replicas decreases with decrease of excitation energy due to more activity of lower energy phonon replicas. In case of undoped ZnO films, three emission peaks in NBE, blue and green regions have been observed. The redshifting with increase of {lambda}{sub ex} in NBE, blue and green regions are found to be 7, 2 and 13 meV, respectively. - Highlights: Black-Right-Pointing-Pointer Influence of {lambda}{sub ex} on PL emission spectra of AZO films has been investigated. Black-Right-Pointing-Pointer The intensity of these peaks decreases exponentially with increase of {lambda}{sub ex}. Black-Right-Pointing-Pointer A redshift has been observed in UV and visible regions with increase of {lambda}{sub ex}.

  15. Effect of pressure and Al doping on structural and optical properties of ZnO nanowires synthesized by chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Mohanta, Antaryami [Oak Ridge Institute for Science and Education, Research Participation Program, U.S. Army Aviation and Missile Research Development and Engineering Center (AMRDEC), Redstone Arsenal, AL 35898 (United States); Simmons, Jay G. [Department of Chemistry, Duke University, Durham, NC 27708 (United States); Everitt, Henry O. [U.S. Army Aviation and Missile Research Development and Engineering Center (AMRDEC), Redstone Arsenal, AL 35898 (United States); Shen, Gang; Margaret Kim, Seongsin [Department of Electrical and Computer Engineering, The University of Alabama, Tuscaloosa, AL 35487 (United States); Kung, Patrick, E-mail: patkung@eng.ua.edu [Department of Electrical and Computer Engineering, The University of Alabama, Tuscaloosa, AL 35487 (United States)

    2014-02-15

    The effect of Al doping concentration and oxygen ambient pressure on the structural and optical properties of chemical vapor deposition-grown, Al-doped ZnO nanowires is studied. As Al doping increases, the strength of the broad visible emission band decreases and the UV emission increases, but the growth rate depends on the oxygen pressure in a complex manner. Together, these behaviors suggest that Al doping is effective in reducing the number of oxygen vacancies responsible for visible emission, especially at low oxygen ambient pressure. The intensities and quantum efficiencies of these emission mechanisms are discussed in terms of the effect growth and doping conditions have on the underlying excitonic decay mechanisms. -- Highlights: • Correlated study of the photoluminescence of undoped and Al-doped ZnO nanowires. • Comparative study of structural and optical properties of ZnO and Al:ZnO nanowires. • Study of excitonic decay relaxation channels as function of pressure and Al doping. • More effective reduction of oxygen vacancies by Al doping at lower pressure.

  16. Effect of Al concentration on the structural, electrical, and optical properties of transparent Al-doped ZnO

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Chang Oh; Shin, Dong Hee; Kim, Sung; Choi, Suk Ho [Kyung Hee University, Yongin (Korea, Republic of)

    2012-08-15

    Al-doped ZnO (AZO) films have been deposited on sapphire substrates at 400 .deg. C for various Al doping concentrations (n{sub Al}) from 0 to 5 wt.% by RF magnetron sputtering and were subsequently annealed at 600 ∼ 800 .deg. C for 3 min. The AZO films show the best structural, electrical, and optical properties at n{sub Al} = ∼2 wt.%, as demonstrated by Hall-effect, photoluminescence, X-ray diffraction, and optical transparency measurements. The n{sub Al}-dependent experimental results are discussed based on possible physical mechanisms. These studies provide a simple method of controlling n{sub Al} for optimizing the properties of AZO films for use as transparent conductive oxides.

  17. Effect of mid-annealing process on the device characteristics of the TFT using Al-doped ZnO active channels prepared by atomic layer deposition

    Science.gov (United States)

    Kim, Eom-Ji; Bak, Jun-Yong; Choi, Jeong-Seon; Yoon, Sung-Min

    2015-03-01

    A specified mid-annealing process, which is a thermal treatment in oxygen ambient right after an active layer deposition, was proposed for obtaining a sufficiently wide process window for the atomic layer deposition in order to realize a high performance Al-doped ZnO (AZO) thin-film transistors (TFTs). While the crystalline phases of the AZO thin films were not changed after the mid-annealing process, the electrical conductivities of the films experienced drastic changes owing to the significant reduction of oxygen vacancies during the mid-annealing process. The decrease in the electrical conductivity was more markedly observed for the AZO films prepared at higher deposition temperature. Top-gate-structured TFTs using the mid-annealed AZO active channel layers were fabricated and characterized. Sound on/off switching behaviors of TFTs were obtained at a wider range of deposition temperature. Additionally, the improvements in carrier mobility and negative bias stress stability were successfully confirmed.

  18. Synthesis and stress relaxation of ZnO/Al-doped ZnO core-shell nanowires.

    Science.gov (United States)

    Wang, Hong-Bo; Ma, Fei; Li, Qian-Qian; Dong, Ce-Zhou; Ma, Da-Yan; Wang, Hong-Tao; Xu, Ke-Wei

    2013-04-07

    Doping nanostructures is an effective method to tune their electrical and photoelectric properties. Taking ZnO nanowires (NWs) as a model system, we demonstrate that atomic layer deposition (ALD) can be adopted for the realization of a doping process by the homo-epitaxial growth of a doped shell on the NW core. The Al-doped ZnO NWs have a layered superlattice structure with dopants mainly occupying the interstitial positions. After annealing, Al(3+) ions diffuse into the ZnO matrix and occupy substitutional locations, which is desirable for dopant activation. The stress accumulated during epitaxial growth is relaxed by the nucleation of dislocations, dislocation dipoles and anti-phase boundaries. We note that the proposed method can be easily adopted for doping different types of nanostructures, and fabricating superlattices and multiple quantum wells on NWs in a controllable way.

  19. Efficiency enhancement of regular-type perovskite solar cells based on Al-doped ZnO nanorods as electron transporting layers

    Science.gov (United States)

    Huang, Zheng-Lun; Chen, Chih-Ming; Lin, Zheng-Kun; Yang, Sheng-Hsiung

    2017-02-01

    In this paper, we first incorporated Al(NO3)3·9H2O as the Al source into ZnO nanorods (NRs) lattice via the hydrothermal method to modify nature properties of ZnO NRs for the fabrication of perovskite solar cells (PSCs). The X-ray diffraction (XRD) pattern of Al-doped ZnO NRs exhibits higher 2θ values and stronger intensity of (002) plane. Larger optical band gap and higher electrical conductivity of Al-doped ZnO NRs are also observed relative to non-doped ZnO ones. The steady-state photoluminescence shows effective charge extraction and collection at the interface between Al-doped ZnO NRs and perovskite layer. The optimized PSC based on Al-doped ZnO NRs showed an open-circuit voltage of 0.84 V, a short-circuit current density of 21.93 mA/cm2, a fill factor of 57%, and a power conversion efficiency of 10.45% that was 23% higher than the non-doped ZnO ones.

  20. Large-scale high aspect ratio Al-doped ZnO nanopillars arrays as anisotropic metamaterials

    DEFF Research Database (Denmark)

    Shkondin, Evgeniy; Takayama, Osamu; Panah, Mohammad Esmail Aryaee

    2017-01-01

    High aspect ratio free-standing Al-doped ZnO (AZO) nanopillars and nanotubes were fabricated using a combination of advanced reactive ion etching and atomic layer deposition (ALD) techniques. Prior to the pillar and tube fabrication, AZO layers were grown on flat silicon and glass substrates...... plasma frequency. During pillar fabrication, AZO conformally passivates the silicon template, which is characteristic of typical ALD growth conditions. The last step of fabrication is heavily dependent on the selective chemistry of the SF6 plasma. It was shown that silicon between AZO structures can...

  1. Enhanced photoelectrochemical performance of CdSe sensitized Al-doped ZnO photoanode compared with CdSe–ZnO

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Jinwen; Fu, Wuyou; Yang, Haibin, E-mail: yanghb@jlu.edu.cn; Cheng, Shuli; Zhang, Lina; Zhou, Xiaoming; Zhang, Yanyan; Sun, Meiling; Yang, Lihua; Zhao, Hui; Chi, Kailin

    2013-10-31

    CdSe nanoparticles sensitized Al-doped ZnO nanorod array films (CdSe–AZO) were prepared via a simple two-step method. The morphological, structural, optical and photoelectrochemical (PEC) properties of the films have been examined. The results confirm that Al element has been implanted into the ZnO lattice structure and distributed in the ZnO nanorod homogenously. CdSe nanoparticles were deposited on Al-doped ZnO nanorod, and the heterojunction interfacial structure of CdSe/AZO was verified by high resolution transmission electron microscopy. The photoresponse of Al-doped ZnO nanorod array films in the visible region has been significantly improved by sensitizing them with CdSe nanoparticles. Under AM 1.5G illumination, the CdSe–AZO electrode have an optimum short-circuit photocurrent density of 4.28 mA cm{sup −2}, nearly 13 times of bare ZnO and 1.7 times of CdSe–ZnO. We attribute the improvement to the fact that Al doping augments more active centers and then increases the amount of CdSe nanoparticles grown on AZO, which leads to significantly enhanced optical absorption and more efficient charge transfer channel. This study provides an insight of combination inorganic semiconductor sensitization with elemental doping for improving PEC properties. - Highlights: • CdSe sensitized Al-doped ZnO nanorod array film (AZO) was prepared. • Al doping induces increased heterostructure area of CdSe/ZnO. • CdSe extends the photoresponse of AZO electrode into the visible light region. • CdSe–AZO shows remarkable improved photoelectrochemical properties than CdSe–ZnO.

  2. Power series fitting of current-voltage characteristics of Al doped ZnO thin film-Sb doped (Ba{sub 0.8}Sr{sub 0.2})TiO{sub 3} heterojunction diode

    Energy Technology Data Exchange (ETDEWEB)

    Sirikulrat, N., E-mail: scphi003@chiangmai.ac.th

    2012-02-29

    The current-voltage (I-V) relationship of aluminum doped zinc oxide thin film-antimony doped barium strontium titanate single heterojunction diodes was investigated. The linear I-V characteristics are similar to those of the PN junction diodes. The linear conduction at a low forward bias voltage as predicted by the space charge limited current theory and the trap free square law at a higher forward voltage are observed. The overall current density-voltage (J-V) characteristics of the diodes are found to be well described by the Power Series Equation J= N-Ary-Summation {sub m}C{sub m}V{sup m} where C{sub m} is the leakage constant at particular power m with the best fit for the power m found to be at the fourth and fifth orders for the forward and reverse bias respectively. - Highlights: Black-Right-Pointing-Pointer The n-n isotype heterojunction diodes of ceramic oxide semiconductors were prepared. Black-Right-Pointing-Pointer The current density-voltage (J-V) curves were analyzed using the Power Series (PS). Black-Right-Pointing-Pointer The J-V characteristics were found to be well described with PS at low order. Black-Right-Pointing-Pointer The thermionic emission and diode leakage currents were comparatively discussed.

  3. ZAO透明导电薄膜微观结构和光电性能的研究%Microstructure and Optoelectrical Properties of Transparent Conductive Al Doped ZnO Thin Films

    Institute of Scientific and Technical Information of China (English)

    钟志有; 顾锦华

    2011-01-01

    以ZnAl2O4陶瓷靶为靶材,采用射频磁控溅射法制备了掺铝氧化锌(ZAO)透明导电薄膜,通过XRD、SEM、四探针仪和分光光度计等测试,研究了沉积温度对薄膜结构、形貌、力学和光电性能的影响.结果表明:ZAO具有(002)择优取向的六角纤锌矿结构,沉积温度对薄膜性能具有明显影响,当温度位于370~ 400℃区间时,薄膜的结晶质量较好、电阻率较低、可见光波段的平均透射率较高,其品质因数大于1.20×10-2S,具有良好的光电综合性能.同时基于透射光谱计算了ZAO薄膜的光学常数,并用有效单振子理论解释了薄膜的折射率色散关系.%Transparent conducting aluminum-doped zinc oxide (ZAO) thin film were deposited by RF magnetron sputtering using using ZnAl2O4 as sintered ceramic target. The influence of deposition temperature on microstructure, morphology, mechanical and optoelectrical properties of ZAO films was investigated by XRD, SEM, four-point probe and spectrophotometer respectively. The results showed that the polycrystalline ZAO films consist of the hexagonal crystal structures with c-axis as the preferred growth orientation normal to the substrate, and that the deposition temperature significantly affects the crystal structures and physical properties of the films. The ZAO films prepared at the deposition temperature of 370-400 ℃ exhibit the higher synthetic optoelectrical properties, which have the relatively well crystallinity, the lower electrical resistivity, the higher average transmittance in the visible light range and the higher figure of merit (1. 20×10 -2 S). Furthermore, the optical bandgap of the ZAO films was calculated using Taucs theory, and the refractive index and extinction coefficient were determined by the envelope method. The dispersion behaviour of the refractive index was studied in terms of the single oscillator model.

  4. Field-emission characteristics of Al-doped ZnO nanostructures hydrothermally synthesized at low temperature.

    Science.gov (United States)

    Yang, Po-Yu; Wang, Jyh-Liang; Tsai, Wei-Chih; Wang, Shui-Jinn; Lin, Jia-Chuan; Lee, I-Che; Chang, Chia-Tsung; Cheng, Huang-Chung

    2011-07-01

    The aluminum-doped ZnO (AZO) nanostructures with different Al concentrations were synthesized on AZO/glass substrate via a simple hydrothermal growth method at a temperature as low as 85 degrees C. The morphologies, crystallinity, optical emission properties, and chemical bonding states of AZO nanostructures show evident dependence on the aluminum dosage. The morphologies of AZO nanostructures were changed from vertically aligned nanowires (NWs), and NWs coexisted with nanosheets (NSs), to complete NSs in respect of the Al-dosages of 0-3 at.%, 5 at.%, and 7 at.%, correspondingly. The undoped ZnO and lightly Al-doped AZO (< or = 3 at.%) NWs are single-crystalline wurtzite structure. In contrast, heavily Al-doped AZO sample is polycrystalline. The AZO nanostructure with 3 at.% Al-dosages reveals the optimal crystallinity and less structural defects, reflecting the longest carrier lifetime and highest conductivity. Consequently, the field-emission characteristics of such an AZO emitter can exhibit the higher current density, larger field-enhancement factor (beta) of 3131, lower turn-on field of 2.17 V/microm, and lower threshold field of 3.43 V/microm.

  5. Enhancement ZnO nanofiber as semiconductor for dye-sensitized solar cells by using Al doped

    Science.gov (United States)

    Sutanto, Bayu; Arifin, Zainal; Suyitno, Hadi, Syamsul; Pranoto, Lia Muliani; Agustia, Yuda Virgantara

    2016-03-01

    The purpose of this research is to produce Al-doped ZnO (AZO) nanofibers in order to enhance the performance of Dye-Sensitized Solar Cell (DSSC). AZO nanofiber semiconductor was manufactured by electrospinning process of Zinc Acetate Dehydrate (Zn(CH3COO)2) solution and precursor of Polyvinyl Acetate (PVA). The doping process of Al was built by dissolving 0-4 wt% in concentrations of AlCl3 to Zinc Acetate. AZO green fiber was sintered at temperature 500°C for an hour. The result shows that Al doped ZnO had capability to increase the electrical conductivity of semiconductor for doping 0, 1, 2, 3, and 4 wt% for 2,07×10-3; 3,71×10-3; 3,59 ×10-3; 3,10 ×10-3 and 2,74 ×10-3 S/m. The best performance of DSSC with 3 cm2 active area was obtained at 1 wt% Al-ZnO which the value of VOC, ISC, FF, and efficiency were 508,43 mV, 3,125 mA, 38,76%, and 0,411% respectively. These coincide with the electrical conductivity of semiconductor and the crystal size of XRD result that has the smallest size as compared to other doping variations.

  6. Growth-controlled surface roughness in Al-doped ZnO as transparent conducting oxide.

    Science.gov (United States)

    Lee, Joon Hwan; Chou, Chia-Yun; Bi, Zhenxing; Tsai, Chen-Fong; Wang, Haiyan

    2009-09-30

    The surface morphology of Al(2)O(3)-doped ZnO (AZO, 2 wt%) thin films varies from a uniform layer to nanorod structure by simply controlling oxygen pressure during growth. All AZO films were deposited on sapphire(0001) substrates using a pulsed laser deposition (PLD) technique. In the low oxygen pressure regime (vacuum approximately 50 mTorr), AZO films grow as a smooth and uniform layer. In the high oxygen pressure regime (100-250 mTorr) AZO thin films with nanorods have formed. Detailed cross-sectional transmission electron microscopy (TEM) and x-ray diffraction (XRD) studies reveal that, besides the obvious variation in the film morphology, the in-plane d spacing of AZO film increases and the out-of-plane d spacing decreases, as oxygen pressure increases. A bilayer AZO film with a nanorod structure on top of a uniform layer was demonstrated by controlling the oxygen pressure for the two layers. Electrical resistivity and optical transmittance measurements were carried out to correlate with the microstructures obtained under different oxygen pressures. The bilayer AZO films could find applications as a transparent conducting oxide (TCO) with a unique light trapping function in thin film solar cells.

  7. Microstructure and characterization of Al-doped ZnO films prepared by RF power sputtering on Al and ZnO targets

    Energy Technology Data Exchange (ETDEWEB)

    Tseng, Chun-An [Department of Mechanical Engineering, National Central University, Taiwan (China); Lin, Jing-Chie, E-mail: jclincom@cc.ncu.edu.tw [Department of Mechanical Engineering, National Central University, Taiwan (China); Institute of Material Science and Engineering, National Central University, Taiwan (China); Chang, Yu-Fong [Department of Mechanical Engineering, National Central University, Taiwan (China); Chyou, San-Der [Power Research Institute, Taiwan Power Company, Taiwan (China); Peng, Kun-Cheng [Department of Materials Science and Engineering, Mingchi University of Technology, Taiwan (China)

    2012-06-01

    Al-doped zinc oxide (AZO) transparent conductive films were prepared on a glass substrate using a magnetron sputtering system with a pure zinc oxide (ZnO) target and a pure Al target sputtered using radio frequency (RF) power. The RF power was set at 100 W for the ZnO target and varied from 20 to 150 W for the Al target. The morphology of the thin films was examined by field-emission scanning electron microscope (FE-SEM), and their composition was analyzed by the equipped energy-dispersive X-ray spectroscopy (EDS). The cross section of the films determined through FE-SEM indicated that their thickness was around 650 nm. EDS analysis revealed that the Al-dopant concentration of the AZO films increased in the following order: 0.85 at.% (20 W) < 1.60 at.% (40 W) < 3.52 at.% (100 W) < 4.34 at.% (150 W). Analysis of the films using X-ray diffractometer (XRD) indicated that all films had a wurtzite structure with a texture of (0 0 2). High-resolution transmission electron microscopy (HRTEM) revealed a number of defects in the films, such as stacking faults and dislocations. Ultraviolet photoelectron spectroscopy (UPS) was used to estimate the optical energy gap (E{sub g}) for the AZO thin films. The energy gap increases from 3.39 to 3.58 eV as the RF power applied to the Al target increase. The electrical resistivity of the films decreased from 3.43 Multiplication-Sign 10{sup -2} {Omega} cm to 3.29 Multiplication-Sign 10{sup -3} {Omega} cm as the RF power increased from 20 to 150 W when a four-point probe was used to investigate. Atomic force microscope (AFM) revealed that the surface roughness of the films increased with increasing RF power. The average optical transmittance of the films was determined by UV-visible spectrometer. The films are suitable for use as transparent conductive oxide films in the optoelectronic industry. A decrease in the electrical resistivity of the film with increasing Al-dopant concentration was ascribed to an increase in the carrier

  8. Electrochemical Synthesis of Highly Oriented, Transparent, and Pinhole-Free ZnO and Al-Doped ZnO Films and Their Use in Heterojunction Solar Cells.

    Science.gov (United States)

    Kang, Donghyeon; Lee, Dongho; Choi, Kyoung-Shin

    2016-10-04

    Electrochemical synthesis conditions using nonaqueous solutions were developed to prepare highly transparent (T > 90%) and crystalline ZnO and Al-doped ZnO (AZO) films for use in solar energy conversion devices. A focused effort was made to produce pinhole-free films in a reproducible manner by identifying a key condition to prevent the formation of cracks during deposition. The polycrystalline domains in the resulting films had a uniform orientation (i.e., the c-axis perpendicular to the substrate), which enhanced the electron transport properties of the films. Furthermore, electrochemical Al doping of ZnO using nonaqueous media, which was demonstrated for the first time in this study, effectively increased the carrier density and raised the Fermi level of ZnO. These films were coupled with an electrodeposited p-type Cu2O to construct p-n heterojunction solar cells to demonstrate the utilization of these films for solar energy conversion. The resulting n-ZnO/p-Cu2O and n-AZO/p-Cu2O cells showed excellent performance compared with previously reported n-ZnO/p-Cu2O cells prepared by electrodeposition. In particular, replacing ZnO with AZO resulted in simultaneous enhancements in short circuit current and open circuit potential, and the n-AZO/p-Cu2O cell achieved an average power conversion efficiency (η) of 0.92 ± 0.09%. The electrodeposition condition reported here will offer a practical and versatile way to produce ZnO or AZO films, which play key roles in various solar energy conversion devices, with qualities comparable to those prepared by vacuum-based techniques.

  9. Thermoelectric properties of Al-doped Mg{sub 2}Si thin films deposited by magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Zhi-jian; Zhou, Bai-yang, E-mail: zby_112921@163.com; Li, Jian-xin; Wen, Cui-lian, E-mail: clwen@fzu.edu.cn

    2016-11-15

    Highlights: • The thin films were fabricated by two-target alternative magnetron sputtering. • The maximum power factor of Al-doped Mg{sub 2}Si thin film we obtained is 3.8 mW m{sup −1} k{sup −2}. • A proper Al dopant can enhance the thermoelectric properties of Mg{sub 2}Si thin films. • Low-dimensional technique can enhance thermoelectric performance effectively. - Abstract: The Al-doped Mg{sub 2}Si thin films were fabricated by two-target alternative magnetron sputtering technique, and the influences of different Al doping contents on the thermoelectric properties of Al-doped Mg{sub 2}Si thin films were investigated. The compositions, crystal structures, electronic transport properties and thermoelectric properties of the thin films were examined using energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), Hall coefficient measurement and Seebeck coefficient measurement system, respectively. The EDS results show that the thin films doped with Al target sputtering power of 30 W, 60 W and 90 W have the Al content of 0.68 at.%, 1.56 at.% and 2.85 at.%, respectively. XRD results indicate that the diffraction peaks of Mg{sub 2}Si become stronger with increasing Al dopant. The results of Hall coefficient measurement and Seebeck coefficient measurement system reveal that all the samples are n-type. The conductivities of Al-doped Mg{sub 2}Si thin films are significantly greater than that of undoped Mg{sub 2}Si thin film, and increase with increasing Al doping content. With the increase of temperature, the absolute value of the Seebeck coefficients of Mg{sub 2}Si base thin films increase firstly and then decrease. The maximum power factor obtained is 3.8 mW m{sup −1} k{sup −2} for 1.56 at.% Al-doped Mg{sub 2}Si thin film at 573 K.

  10. An insight to the low temperature conduction mechanism of c-axis grown Al-doped ZnO, a widely used transparent conducting oxide

    Science.gov (United States)

    Murali, Banavoth; Parui, Jayanta; Madhuri, M.; Krupanidhi, S. B.

    2015-01-01

    Al-doped ZnO thin films were synthesized from oxygen reactive co-sputtering of Al and Zn targets. Explicit doping of Al in the highly c-axis oriented crystalline films of ZnO was manifested in terms of structural optical and electrical properties. Electrical conduction with different extent of Al doping into the crystal lattice of ZnO (AZnO) were characterized by frequency dependent (40 Hz-50 MHz) resistance. From the frequency dependent resistance, the ac conduction of them, and correlations of localized charge particles in the crystalline films were studied. The dc conduction at the low frequency region was found to increase from 8.623 µA to 1.14 mA for the samples AZnO1 (1 wt% Al) and AZnO2 (2 wt% Al), respectively. For the sample AZnO10 (10 wt% Al) low frequency dc conduction was not found due to the electrode polarization effect. The measure of the correlation length by inverse of threshold frequency (ω0) showed that on application of a dc electric field such length decreases and the decrease in correlation parameter(s) indicates that the correlation between potentials wells of charge particles decreases for the unidirectional nature of dc bias. The comparison between the correlation length and the extent of correlation in the doped ZnO could not be made due to the observation of several threshold frequencies at the extent of higher doping. Such threshold frequencies were explained by the population possibility of correlated charge carriers that responded at different frequencies. For AZnO2 (2% Al), the temperature dependent (from 4.5 to 288 K) resistance study showed that the variable range hopping mechanism was the most dominating conduction mechanism at higher temperature whereas at low temperature region it was influenced by the small polaronic hopping conduction mechanism. There was no significant influence found in these mechanisms on applications of 1, 2 and 3 V as biases.

  11. Highly ordered Al-doped ZnO nano-pillar and tube structures as hyperbolic metamaterials for mid-infrared plasmonics

    DEFF Research Database (Denmark)

    Shkondin, Evgeniy; Takayama, Osamu; Panah, Mohammad Esmail Aryaee

    Fabrication of large area metamaterial structures in a reproducible manner is a tremendous challenge. Here, we realize the fabrication of plasmonic metamaterials for the mid-infrared wavelength region composed of Al-doped ZnO (AZO) pillars by a combination of atomic layer deposition and reactive...

  12. On performance limitations and property correlations of Al-doped ZnO deposited by radio-frequency sputtering

    Science.gov (United States)

    Crovetto, Andrea; Sand Ottsen, Tobias; Stamate, Eugen; Kjær, Daniel; Schou, Jørgen; Hansen, Ole

    2016-07-01

    The electrical properties of RF-sputtered Al-doped ZnO are often spatially inhomogeneous and strongly dependent on deposition parameters. In this work, we study the mechanisms that limit the minimum resistivity achievable under different deposition regimes. In a low- and intermediate-pressure regime, we find a generalized dependence of the electrical properties, grain size, texture, and Al content on compressive stress, regardless of sputtering pressure or position on the substrate. In a high-pressure regime, a porous microstructure limits the achievable resistivity and causes it to increase over time as well. The primary cause of inhomogeneity in the electrical properties is identified as energetic particle bombardment. Inhomogeneity in oxygen content is also observed, but its effect on the electrical properties is small and limited to the carrier mobility.

  13. Fabrication and characterization of silicon wire solar cells having ZnO nanorod antireflection coating on Al-doped ZnO seed layer.

    Science.gov (United States)

    Baek, Seong-Ho; Noh, Bum-Young; Park, Il-Kyu; Kim, Jae Hyun

    2012-01-05

    In this study, we have fabricated and characterized the silicon [Si] wire solar cells with conformal ZnO nanorod antireflection coating [ARC] grown on a Al-doped ZnO [AZO] seed layer. Vertically aligned Si wire arrays were fabricated by electrochemical etching and, the p-n junction was prepared by spin-on dopant diffusion method. Hydrothermal growth of the ZnO nanorods was followed by AZO film deposition on high aspect ratio Si microwire arrays by atomic layer deposition [ALD]. The introduction of an ALD-deposited AZO film on Si wire arrays not only helps to create the ZnO nanorod arrays, but also has a strong impact on the reduction of surface recombination. The reflectance spectra show that ZnO nanorods were used as an efficient ARC to enhance light absorption by multiple scattering. Also, from the current-voltage results, we found that the combination of the AZO film and ZnO nanorods on Si wire solar cells leads to an increased power conversion efficiency by more than 27% compared to the cells without it.

  14. Al-doped ZnO contact to CdZnTe for x- and gamma-ray detector applications

    Science.gov (United States)

    Roy, U. N.; Camarda, G. S.; Cui, Y.; Gul, R.; Hossain, A.; Yang, G.; Mundle, R. M.; Pradhan, A. K.; James, R. B.

    2016-06-01

    The poor adhesion of common metals to CdZnTe (CZT)/CdTe surfaces has been a long-standing challenge for radiation detector applications. In this present work, we explored the use of an alternative electrode, viz., Al-doped ZnO (AZO) as a replacement to common metallic contacts. ZnO offers several advantages over the latter, such as having a higher hardness, a close match of the coefficients of thermal expansion for CZT and ZnO, and better adhesion to the surface of CZT due to the contact layer being an oxide. The AZO/CZT contact was investigated via high spatial-resolution X-ray response mapping for a planar detector at the micron level. The durability of the device was investigated by acquiring I-V measurements over an 18-month period, and good long-term stability was observed. We have demonstrated that the AZO/CZT/AZO virtual-Frisch-grid device performs fairly well, with comparable or better characteristics than that for the same detector fabricated with gold contacts.

  15. Polymer solar cells with efficiency >10% enabled via a facile solution-processed Al-doped ZnO electron transporting layer

    KAUST Repository

    Jagadamma, Lethy Krishnan

    2015-10-05

    The present work details a facile and low-temperature (125C) solution-processed Al-doped ZnO (AZO) buffer layer functioning very effectively as electron accepting/hole blocking layer for a wide range of polymer:fullerene bulk heterojunction systems, and yielding power conversion efficiency in excess of 10% (8%) on glass (plastic) substrates. We show that ammonia addition to the aqueous AZO nanoparticle solution is a critically important step toward producing compact and smooth thin films which partially retain the aluminum doping and crystalline order of the starting AZO nanocrystals. The ammonia treatment appears to reduce the native defects via nitrogen incorporation, making the AZO film a very good electron transporter and energetically matched with the fullerene acceptor. Importantly, highly efficient solar cells are achieved without the need for additional surface chemical passivation or modification, which has become an increasingly common route to improving the performance of evaporated or solution-processed ZnO ETLs in solar cells.

  16. Polymer solar cells with efficiency >10% enabled via a facile solution-processed Al-doped ZnO electron transporting layer (Presentation Recording)

    Science.gov (United States)

    Jagadamma, Lethy K.; Al-Senani, Mohammed; Amassian, Aram

    2015-10-01

    The present work details a facile and low-temperature (125C) solution-processed Al-doped ZnO (AZO) buffer layer functioning very effectively as electron accepting/hole blocking layer for a wide range of polymer:fullerene bulk heterojunction systems, and yielding power conversion efficiency in excess of 10% (8%) on glass (plastic) substrates. We show that ammonia addition to the aqueous AZO nanoparticle solution is a critically important step toward producing compact and smooth thin films which partially retain the aluminum doping and crystalline order of the starting AZO nanocrystals. The ammonia treatment appears to reduce the native defects via nitrogen incorporation, making the AZO film a very good electron transporter and energetically matched with the fullerene acceptor. Importantly, highly efficient solar cells are achieved without the need for additional surface chemical passivation or modification, which has become an increasingly common route to improving the performance of evaporated or solution-processed ZnO ETLs in solar cells.

  17. Electrical stability of Al-doped ZnO transparent electrode prepared by sol-gel method

    Science.gov (United States)

    Tabassum, Samia; Yamasue, Eiji; Okumura, Hideyuki; Ishihara, Keiichi N.

    2016-07-01

    Al-doped zinc oxide (AZO) thin films have been considered as a promising alternative to tin doped indium oxide (ITO), which is currently used in various optoelectronic applications. However, the environmental stability of AZO film is not satisfactory, in that the resistivity is significantly increases in air. Here, we investigate the resistivity stability of AZO thin films prepared by sol-gel method using various annealing temperatures and durations. The degradation of resistivity property was observed for AZO films stored in ambient or damp heat environment, where the degradation rate was influenced by annealing temperature. A significant improvement of electrical stability was attained in AZO films that were prepared at high annealing temperature. The films, which showed the highest and the lowest increasing rate of resistivity, were further characterized in detail to shed light on the possible mechanisms explaining the improved stability through crystallinity, surface morphology and elemental state of the thin film.

  18. Synthesis of High Crystalline Al-Doped ZnO Nanopowders from Al2O3 and ZnO by Radio-Frequency Thermal Plasma

    Directory of Open Access Journals (Sweden)

    Min-Kyeong Song

    2015-01-01

    Full Text Available High crystalline Al-doped ZnO (AZO nanopowders were prepared by in-flight treatment of ZnO and Al2O3 in Radio-Frequency (RF thermal plasma. Micron-sized (~1 μm ZnO and Al2O3 powders were mixed at Al/Zn ratios of 3.3 and 6.7 at.% and then injected into the RF thermal plasma torch along the centerline at a feeding rate of 6.6 g/min. The RF thermal plasma torch system was operated at the plate power level of ~140 kVA to evaporate the mixture oxides and the resultant vapor species were condensed into solid particles by the high flow rate of quenching gas (~7000 slpm. The FE-SEM images of the as-treated powders showed that the multipod shaped and the whisker type nanoparticles were mainly synthesized. In addition, these nanocrystalline structures were confirmed as the single phase AZO nanopowders with the hexagonal wurtzite ZnO structure by the XRD patterns and FE-TEM results with the SAED image. However, the composition changes of 0.3 and 1.0 at.% were checked for the as-synthesized AZO nanopowders at Al/Zn ratios of 3.3 and 6.7 at.%, respectively, by the XRF data, which can require the adjustment of Al/Zn in the mixture precursors for the applications of high Al doping concentrations.

  19. Fabrication of nanowires of Al-doped ZnO using nanoparticle assisted pulsed laser deposition (NAPLD) for device applications

    Energy Technology Data Exchange (ETDEWEB)

    Thanka Rajan, S. [ECMS Division, CSIR – Central Electrochemical Research Institute, Karaikudi 630 006 (India); Subramanian, B., E-mail: subramanianb3@gmail.com [ECMS Division, CSIR – Central Electrochemical Research Institute, Karaikudi 630 006 (India); Nanda Kumar, A.K.; Jayachandran, M. [ECMS Division, CSIR – Central Electrochemical Research Institute, Karaikudi 630 006 (India); Ramachandra Rao, M.S. [Department of Physics, Indian Institute of Technology Madras, Chennai 600 036 (India)

    2014-01-25

    Graphical abstract: -- Highlights: • Novel technique of NP assisted PLD was employed to obtain Al doped ZnO. • AZO nano wires with aspect ratios exceeding 20 were obtained at 500 sccm Ar gas pressure. • AZO films belong to the most stable wurtzite type. • Films show near band edge emission and defect related emission. -- Abstract: Aluminium doped zinc oxide (AZO) nanostructures have been successfully synthesized on sapphire substrates by using nanoparticle assisted pulsed laser deposition (NAPLD) in Ar atmosphere without using any catalyst. The growth of the AZO nanowires has been investigated by varying the argon flow rates. The coatings have been characterized by X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM), Atomic force microscopy (AFM), Diffuse Reflectance Spectroscopy (DRS), Laser Raman spectroscopy and Photoluminescence spectroscopy. The results of XRD indicate that the deposited films are crystalline ZnO with hexagonal wurtzite structure with (0 0 2) preferred orientation. FESEM images also clearly reveal the hexagonal structure and the formation of nanowires with aspect ratios between 15 and 20. The surface roughness value of 9.19 nm was observed from AFM analysis. The optical properties of the sample showed that under excitation with λ = 325 nm, an emission band was observed in UV and visible region. The characteristic Raman peaks were detected at 328, 380, 420, 430 cm{sup −1}.

  20. Spectroscopic characterization of the plasmas formed during the deposition of ZnO and Al-doped ZnO films by plasma-assisted pulsed laser deposition

    Science.gov (United States)

    Liang, Peipei; Cai, Hua; Yang, Xu; Li, Hui; Zhang, Wu; Xu, Ning; Sun, Jian; Wu, Jiada

    2016-11-01

    An oxygen-zinc plasma and an oxygen-zinc-aluminum plasma are formed by pulsed laser ablation of a Zn target or pulsed laser co-ablation of a Zn target and an Al target in an electron cyclotron resonance (ECR) discharge-generated oxygen plasma for the deposition of ZnO and Al-doped ZnO (AZO) films. The plasmas are characterized spectroscopically by time-integrated and time-resolved optical emission spectroscopy. Both the oxygen-zinc plasma and the oxygen-zinc-aluminum plasma contain excited species originally present in the working O2 gas and energetic species ablated from the targets. The optical emission of the oxygen-zinc-aluminum plasma is abundant in the emission bands of oxygen molecular ions and the emission lines of mono-atomic oxygen, zinc and aluminum atoms and atomic ions. The time-integrated spectra as well as the time-resolved spectra of the plasma emission indicate that the oxygen species in the ECR oxygen plasma experience additional excitation by the expanding ablation plumes, and the ablated species are excited frequently when traveling accompanying the plume expansion in the oxygen plasma, making the formed plasma highly excited and very reactive, which plays an important role in the reactive growth of ZnO matrix and the in-situ doping of Al into the growing ZnO matrix. The deposited ZnO and AZO films were evaluated for composition analysis by energy dispersive X-ray spectroscopy, structure characterization by X-ray diffraction and optical transmission measurement. The deposited ZnO is slightly rich in O. The Al concentration of the AZO films can be controlled and varied simply by changing the repetition rate of the laser used for Al target ablation. Both the ZnO and the AZO films are featured with hexagonal wurtzite crystal structure and exhibit high optical transparency in a wide spectral region. Al doping results in an improvement in the ultraviolet transparency, a blue shift in the absorption edge and a widening of the band gap.

  1. Growth of Al-doped ZnO films with tilted nano-columns on r-cut sapphire substrates by pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Joon Hwan [Material Science and Engineering Program, Texas A and M University, College Station, Texas 77843-3128 (United States); Lu, Tianlin; Cho, Sungmee; Khatkatay, Fauzia [Department of Electrical and Computer Engineering, Texas A and M University, College Station, Texas 77843-3128 (United States); Chen, Li [Material Science and Engineering Program, Texas A and M University, College Station, Texas 77843-3128 (United States); Wang, Haiyan, E-mail: wangh@ece.tamu.edu [Material Science and Engineering Program, Texas A and M University, College Station, Texas 77843-3128 (United States); Department of Electrical and Computer Engineering, Texas A and M University, College Station, Texas 77843-3128 (United States)

    2012-12-01

    2 wt.% Al{sub 2}O{sub 3}-doped ZnO (AZO) thin films in both single layer and bi-layer forms were deposited on {alpha}-Al{sub 2}O{sub 3} (011{sup Macron }2) (r-cut) and (0001) (c-cut) substrates by a pulsed laser deposition technique. Single layer AZO films were grown under either vacuum or 33.3 Pa of O{sub 2} pressure. Bilayer AZO films were grown with a sequential deposition of a uniform template layer under vacuum and a nano-column-structured layer under 33.3 Pa of O{sub 2} pressure. Interestingly, single layer AZO film grown on r-cut sapphire in high oxygen pressure (33.3 Pa) shows tilted grain boundaries along [1{sup Macron }102{sup Macron }]{sub AZO}. The bilayer film deposited on r-cut substrate shows tilted nano-column growth while the film grown on c-cut substrate has vertically grown nano-columns. The results of X-ray diffraction and cross-section transmission electron microscopy studies show a systematic variation of the d-spacing of (0002){sub AZO} and (112{sup Macron }0){sub AZO} for all AZO films. Electrical resistivity was measured and found to be strongly dependent on the different microstructures achieved under different oxygen pressures and substrates. - Highlights: Black-Right-Pointing-Pointer 2 wt.% Al doped ZnO (AZO) thin film grown on r-cut sapphire under 33.3 Pa of O{sub 2} Black-Right-Pointing-Pointer Tiled boundary along [1{sup Macron }102{sup Macron }]{sub AZO} observed as a result of internal lattice strain Black-Right-Pointing-Pointer Tilted nano-column processed after sequential deposition under vacuum and 33.3 Pa of O{sub 2} Black-Right-Pointing-Pointer Significantly reduced electrical resistivity observed for the films on r-cut sapphire.

  2. Transparent Al-doped ZnO anodes in organic light-emitting diodes investigated using a hole-only device

    Energy Technology Data Exchange (ETDEWEB)

    Tseng, Zong-Liang [Department of Electrical Engineering, National Cheng Kung University, Tainan 701, Taiwan (China); Kao, Po-Ching [Department of Electrophysics, National Chiayi University, Chiayi 600-83, Taiwan (China); Yang, Chi-Shin [Department of Electrical Engineering, National Cheng Kung University, Tainan 701, Taiwan (China); Juang, Yung-Der [Department of Material Science, National University of Tainan, Tainan 70005, Taiwan (China); Department of Greenergy, National University of Tainan, Tainan 70005, Taiwan (China); Chu, Sheng-Yuan, E-mail: chusy@mail.ncku.edu.tw [Department of Electrical Engineering, National Cheng Kung University, Tainan 701, Taiwan (China); Advanced Optoelectronic Technology Center, National Cheng Kung University, Tainan 701, Taiwan (China)

    2012-11-15

    Highlights: Black-Right-Pointing-Pointer OLED devices with AZO films and commercial ITO. Black-Right-Pointing-Pointer Hole-only devices with AZO film and commercial ITO anodes were used to examine the efficiency of hole injection. Black-Right-Pointing-Pointer AZO films are suitable as anodes of OLED devices under a high applied voltage. Black-Right-Pointing-Pointer The indium diffuses into the organic layer. - Abstract: Al-doped ZnO (AZO) films with a thickness of {approx}400 nm were prepared by sputtering on glass substrates for use as transparent anodes of organic light-emitting diodes (OLED) devices. The operation voltages (at 100 cd/m{sup 2}) of OLED devices with AZO and ITO anode materials were 10.5 and 5.5 V, respectively. The maximum luminance output of the AZO device was 6450 cd/m{sup 2} (achieved at 12.5 V) and that of the ITO device was 9830 cd/m{sup 2} (achieved at 10.5 V). We demonstrate that a hole-only device method can be used to estimate the suitability of AZO and ITO anodes in the OLED devices and to verify experimental results. The AZO thin films with low price and non-toxicity may be suitable as alternative anodes in OLED devices under high voltage.

  3. Polymer Solar Cells with Efficiency >10% Enabled via a Facile Solution-Processed Al-Doped ZnO Electron Transporting Layer

    KAUST Repository

    Jagadamma, Lethy Krishnan

    2015-04-22

    A facile and low-temperature (125 °C) solution-processed Al-doped ZnO (AZO) buffer layer functioning very effectively as electron accepting/hole blocking layer for a wide range of polymer:fullerene bulk heterojunction systems, yielding power conversion efficiency in excess of 10% (8%) on glass (plastic) substrates is described. The ammonia-treatment of the aqueous AZO nanoparticle solution produces compact, crystalline, and smooth thin films, which retain the aluminum doping, and eliminates/reduces the native defects by nitrogen incorporation, making them good electron transporters and energetically matched with the fullerene acceptor. It is demonstrated that highly efficient solar cells can be achieved without the need for additional surface chemical modifications of the buffer layer, which is a common requirement for many metal oxide buffer layers to yield efficient solar cells. Also highly efficient solar cells are achieved with thick AZO films (>50 nm), highlighting the suitability of this material for roll-to-roll coating. Preliminary results on the applicability of AZO as electron injection layer in F8BT-based polymer light emitting diode are also presented. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Electrodeposition of nanoporous ZnO on Al-doped ZnO leading to a highly organized structure for integration in Dye Sensitized Solar Cells

    Directory of Open Access Journals (Sweden)

    Renou G.

    2010-10-01

    Full Text Available In the present study, we propose an improvement of the anode configuration in Zinc Oxide based Dye Sensitized Solar Cells (DSSC. Instead of the classical configuration, which is composed by two different metal oxides: one transparent conducting oxide (TCO for the substrate and one nanostructured metal oxide for supporting the dye, the new approach is to use ZnO as unique material. Thus, nanoporous zinc oxide films have been electrodeposited on a sputtered Al doped ZnO layers with varying thicknesses up to 6 μm. The evolution of the porosity of the structure has been studied by scanning electron microscope (SEM and electrochemical impedance spectroscopy and compared with standard nanoporous ZnO grown on fluorine doped tin oxide (SnO2:F noted FTO. This results firstly in the modification of the nanoporous structure morphology and secondly a better adhesion between the nanoporous layer and the substrate. Organization in the nanoporous material is enhanced with regular pores arrays and perpendicular to the substrate. Dye sensitized solar cells based on this simplified architecture present efficiencies up to 4.2% and 4.5% with N719 and D149 respectively as sensitizers. Higher fill factor and Voc are found in comparison with the one obtained for deposition on the classical transparent conducting oxide (FTO, which denote improved electrical transfer properties.

  5. Characteristics of Al-doped ZnO films grown by atomic layer deposition for silicon nanowire photovoltaic device.

    Science.gov (United States)

    Oh, Byeong-Yun; Han, Jin-Woo; Seo, Dae-Shik; Kim, Kwang-Young; Baek, Seong-Ho; Jang, Hwan Soo; Kim, Jae Hyun

    2012-07-01

    We report the structural, electrical, and optical characteristics of Al-doped ZnO (ZnO:Al) films deposited on glass by atomic layer deposition (ALD) with various Al2O3 film contents for use as transparent electrodes. Unlike films fabricated by a sputtering method, the diffraction peak position of the films deposited by ALD progressively moved to a higher angle with increasing Al2O3 film content. This indicates that Zn sites were effectively replaced by Al, due to layer-by-layer growth mechanism of ALD process which is based on alternate self-limiting surface chemical reactions. By adjusting the Al2O3 film content, a ZnO:Al film with low electrical resistivity (9.84 x 10(-4) Omega cm) was obtained at an Al2O3 film content of 3.17%, where the Al concentration, carrier mobility, optical transmittance, and bandgap energy were 2.8 wt%, 11.20 cm2 V(-1) s(-1), 94.23%, and 3.6 eV, respectively. Moreover, the estimated figure of merit value of our best sample was 8.2 m7Omega(-1). These results suggest that ZnO:Al films deposited by ALD could be useful for electronic devices in which especially require 3-dimensional conformal deposition of the transparent electrode and surface passivation.

  6. Local probe microscopic studies on Al-doped ZnO: Pseudoferroelectricity and band bending at grain boundaries

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Mohit; Basu, Tanmoy; Som, Tapobrata, E-mail: tsom@iopb.res.in [SUNAG Laboratory, Institute of Physics, Sachivalaya Marg, Bhubaneswar 751 005 (India)

    2016-01-07

    In this paper, based on piezoforce measurements, we show the presence of opposite polarization at grains and grain boundaries of Al-doped ZnO (AZO). The polarization can be flipped by 180° in phase by switching the polarity of the applied electric field, revealing the existence of nanoscale pseudoferroelectricity in AZO grown on Pt/TiO{sub 2}/SiO{sub 2}/Si substrate. We also demonstrate an experimental evidence on local band bending at grain boundaries of AZO films using conductive atomic force microscopy and Kelvin probe force microscopy. The presence of an opposite polarization at grains and grain boundaries gives rise to a polarization-driven barrier formation at grain boundaries. With the help of conductive atomic force microscopy, we show that the polarization-driven barrier along with the defect-induced electrostatic potential barrier account for the measured local band bending at grain boundaries. The present study opens a new avenue to understand the charge transport in light of both polarization and electrostatic effects.

  7. Fabrication of deep-profile Al-doped ZnO one- and two-dimensional lattices as plasmonic elements

    Science.gov (United States)

    Jensen, Flemming; Shkondin, Evgeniy; Takayama, Osamu; Larsen, Pernille V.; Mar, Mikkel D.; Malureanu, Radu; Lavrinenko, Andrei V.

    2016-09-01

    In this work, we report on fabrication of deep-profile one- and two-dimensional lattices made from Al-doped ZnO (AZO). AZO is considered as an alternative plasmonic material having the real part of the permittivity negative in the near infrared range. The exact position of the plasma frequency of AZO is doping concentration dependent, allowing for tuning possibilities. In addition, the thickness of the AZO film also affects its material properties. Physical vapor deposition techniques typically applied for AZO coating do not enable deep profiling of a plasmonic structure. Using the atomic layer deposition technique, a highly conformal deposition method, allows us to fabricate high-aspect ratio structures such as one-dimensional lattices with a period of 400 nm and size of the lamina of 200 nm in width and 3 μm in depth. Thus, our structures have an aspect ratio of 1:15 and are homogeneous on areas of 2×2 cm2 and more. We also produce two-dimensional arrays of circular nanopillars with similar dimensions. Instead of nanopillars hollow tubes with a wall thickness on demand from 20 nm up to a complete fill can be fabricated.

  8. Local probe microscopic studies on Al-doped ZnO: Pseudoferroelectricity and band bending at grain boundaries

    Science.gov (United States)

    Kumar, Mohit; Basu, Tanmoy; Som, Tapobrata

    2016-01-01

    In this paper, based on piezoforce measurements, we show the presence of opposite polarization at grains and grain boundaries of Al-doped ZnO (AZO). The polarization can be flipped by 180° in phase by switching the polarity of the applied electric field, revealing the existence of nanoscale pseudoferroelectricity in AZO grown on Pt/TiO2/SiO2/Si substrate. We also demonstrate an experimental evidence on local band bending at grain boundaries of AZO films using conductive atomic force microscopy and Kelvin probe force microscopy. The presence of an opposite polarization at grains and grain boundaries gives rise to a polarization-driven barrier formation at grain boundaries. With the help of conductive atomic force microscopy, we show that the polarization-driven barrier along with the defect-induced electrostatic potential barrier account for the measured local band bending at grain boundaries. The present study opens a new avenue to understand the charge transport in light of both polarization and electrostatic effects.

  9. pH-Sensing Characteristics of Hydrothermal Al-Doped ZnO Nanostructures

    OpenAIRE

    Jyh-Liang Wang; Po-Yu Yang; Tsang-Yen Hsieh; Chuan-Chou Hwang; Miin-Horng Juang

    2013-01-01

    Highly sensitive and stable pH-sensing properties of an extended-gate field-effect transistor (EGFET) based on the aluminum-doped ZnO (AZO) nanostructures have been demonstrated. The AZO nanostructures with different Al concentrations were synthesized on AZO/glass substrate via a simple hydrothermal growth method at 85°C. The AZO sensing nanostructures were connected with the metal-oxide-semiconductor field-effect transistor (MOSFET). Afterwards, the current-voltage (I-V) characteristics and ...

  10. Studies on the properties of sputter-deposited Al-doped ZnO films

    Science.gov (United States)

    Selmi, M.; Chaabouni, F.; Abaab, M.; Rezig, B.

    2008-09-01

    ZnO is a well known material; however, the research interest in this material is still high enough because ZnO is one of the materials with the most potential for optoelectronics due to its promising properties of high conductivity as well as good transparency. In this work, aluminum doped zinc oxide films (ZnO:Al) were deposited by RF magnetron sputtering on glass and silicon substrates with different deposition times of 2, 3 and 4 h. The aim of this work is the study of the deposition time effect on the properties of ZnO:Al films. It is shown that films grow with the hexagonal c-axis perpendicular to the substrate surface. The morphological characteristics show a granular and homogenous surface and the cristallinity of the films is enhanced with increased deposition time. The deposited films show good optical transmittance (80%-90%) in the visible and near infrared spectrum. The calculated band gap is about 3.3 eV. The electrical ZnO:Al/Si(p) junction properties were investigated using the Capacitance-Voltage ( C-V) dependence. Calculations of the built-in potential from classical 1/C2-V characterization give values between 0.54 and 0.71 V. This work shows how the variation of deposition time allows the control of structural, electrical and optical properties of the films.

  11. Electrical and optical properties of Al-doped ZnO and ZnAl2O4 films prepared by atomic layer deposition.

    Science.gov (United States)

    Hou, Qiongqiong; Meng, Fanjie; Sun, Jiaming

    2013-03-28

    ZnO/Al2O3 multilayers were prepared by alternating atomic layer deposition (ALD) at 150°C using diethylzinc, trimethylaluminum, and water. The growth process, crystallinity, and electrical and optical properties of the multilayers were studied with a variety of the cycle ratios of ZnO and Al2O3 sublayers. Transparent conductive Al-doped ZnO films were prepared with the minimum resistivity of 2.4 × 10-3 Ω·cm at a low Al doping concentration of 2.26%. Photoluminescence spectroscopy in conjunction with X-ray diffraction analysis revealed that the thickness of ZnO sublayers plays an important role on the priority for selective crystallization of ZnAl2O4 and ZnO phases during high-temperature annealing ZnO/Al2O3 multilayers. It was found that pure ZnAl2O4 film was synthesized by annealing the specific composite film containing alternative monocycle of ZnO and Al2O3 sublayers, which could only be deposited precisely by utilizing ALD technology.

  12. In situ Al-doped ZnO films by atomic layer deposition with an interrupted flow

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Jheng-Ming [Program for Science and Technology of Accelerator Light Source, National Chiao Tung University, Hsinchu 300, Taiwan (China); Ku, Ching-Shun [National Synchrotron Radiation Research Center, 101 Hsin-Ann Road, Hsinchu Science Park, Hsinchu 30076, Taiwan (China); Lin, Chih-Ming, E-mail: cmlin@mail.nhcue.edu.tw [Department of Applied Science, National Hsinchu University of Education, Hsinchu 30014, Taiwan (China); Chen, San-Yuan [Department of Materials Science and Engineering, National Chiao Tung University, Hsinchu 300, Taiwan (China); Lee, Hsin-Yi, E-mail: hylee@nsrrc.org.tw [National Synchrotron Radiation Research Center, 101 Hsin-Ann Road, Hsinchu Science Park, Hsinchu 30076, Taiwan (China); Department of Applied Science, National Hsinchu University of Education, Hsinchu 30014, Taiwan (China)

    2015-09-01

    In situ aluminum-doped ZnO (AZO) films were grown on glass substrates by atomic layer deposition (ALD) with an interrupted flow at temperatures in range 200–280 °C; the optimal temperature, 260 °C, depended on the electrical properties. To assess the effect of the ratio of pulses of diethylzinc (DEZn) and trimethylaluminium (TMA) on the structural, optical and electrical properties, we grew AZO films with various pulse ratios of DEZn:TMA in a range from 3:1 to 10:1 at 260 °C. These properties and the content of Al were investigated with X-ray diffraction, X-ray reflectivity (XRR), a high-resolution transmission electron microscope (HRTEM), a secondary-ion mass spectrometer (SIMS), transmission spectra, Hall measurements and X-ray photoelectron spectra (XPS). The electrical resistivity was least, 5.7 × 10{sup −4} Ω cm, for ALD-AZO films with pulse ratio 6:1; the carrier mobility was 8.80 cm{sup 2} V{sup −1} s{sup −1} and optical transmittance up to 94%. The epitaxial AZO films grown in situ also on m-plane sapphire exhibited the two-fold symmetry of ZnO (110) in the orthorhombic crystal system. All results show that a novel in situ doping method with an interrupted flow controls the Al content of AZO films more easily, and is more usefully applicable for a structure with a large aspect ratio for an advanced photoelectric device. - Highlights: • In situ Al-doped ZnO films were grown on glass substrates by ALD with an interrupted flow. • AZO films deposited at 260 °C show superior electrical and optical properties. • In situ doping method provides highly crystalline quality and improves the electrical properties. • In situ doping method controls the Al content of AZO films more easily. • In situ doping method is more suitable for a structure with a large aspect ratio for an advanced photoelectric device.

  13. Influence of Al-doped ZnO and Ga-doped ZnO substrates on third harmonic generation of gold nanoparticles

    Science.gov (United States)

    Kityk, I. V.; AlZayed, N. S.; Kobayashi, Kei; Chen, Xiaomei; Oyama, Munetaka; El-Naggar, A. M.; Albassam, A. A.

    2015-07-01

    Principal role of substrate types on the nonlinear optical properties of Au NP was investigated. Third harmonic generation (THG) studies were carried out for Au NP deposited on the Al-doped ZnO (AuNP/AZO) and Ga-doped ZnO (AuNP/GZO) substrates at fundamental wavelength of 20 ns Er:glass laser (generating at 1540 nm wavelength) during photostimulation by the 532 nm 15 ns laser pulses. Sizes of Au NP were 5 nm, 10 nm, 20 nm, and 30 nm. The output signal was registered at 513 nm. The photoinduced power density was increased from 0 up to 800 MW/cm2. So in our work we explore the role of the substrate on the optically stimulated non-linear optical properties during simultaneous photo stimulation near the inter-band transition. The results were studied depending on the type of substrate and the sizes of the deposited nanoparticles. The analysis was done within a framework of interaction between the photoinduced light and SPR wavelengths. Control of the photoinduced temperature was done.

  14. Carrier Compensation Induced by Thermal Annealing in Al-Doped ZnO Films

    Directory of Open Access Journals (Sweden)

    Takashi Koida

    2017-02-01

    Full Text Available This study investigated carrier compensation induced by thermal annealing in sputtered ZnO:Al (Al2O3: 0.25, 0.5, 1.0, and 2.0 wt % films. The films were post-annealed in a N2 atmosphere at low (1 × 10−23 atm and high (1 × 10−4 atm oxygen partial pressures (PO2. In ZnO:Al films with low Al contents (i.e., 0.25 wt %, the carrier density (n began to decrease at annealing temperatures (Ta of 600 °C at low PO2. At higher PO2 and/or Al contents, n values began to decrease significantly at lower Ta (ca. 400 °C. In addition, Zn became desorbed from the films during heating in a high vacuum (i.e., <1 × 10−7 Pa. These results suggest the following: (i Zn interstitials and Zn vacancies are created in the ZnO lattice during post-annealing treatments, thereby leading to carrier compensation by acceptor-type Zn vacancies; (ii The compensation behavior is significantly enhanced for ZnO:Al films with high Al contents.

  15. pH-Sensing Characteristics of Hydrothermal Al-Doped ZnO Nanostructures

    Directory of Open Access Journals (Sweden)

    Jyh-Liang Wang

    2013-01-01

    Full Text Available Highly sensitive and stable pH-sensing properties of an extended-gate field-effect transistor (EGFET based on the aluminum-doped ZnO (AZO nanostructures have been demonstrated. The AZO nanostructures with different Al concentrations were synthesized on AZO/glass substrate via a simple hydrothermal growth method at 85°C. The AZO sensing nanostructures were connected with the metal-oxide-semiconductor field-effect transistor (MOSFET. Afterwards, the current-voltage (I-V characteristics and the sensing properties of the pH-EGFET sensors were obtained in different buffer solutions, respectively. As a result, the pH-sensing characteristics of AZO nanostructured pH-EGFET sensors with Al dosage of 3 at.% can exhibit the higher sensitivity of 57.95 mV/pH, the larger linearity of 0.9998, the smaller deviation of 0.023 in linearity, the lower drift rate of 1.27 mV/hour, and the lower threshold voltage of 1.32 V with a wider sensing range (pH 1 ~ pH 13. Hence, the outstanding stability and durability of AZO nanostructured ionic EGFET sensors are attractive for the electrochemical application of flexible and disposable biosensor.

  16. Room temperature deposition of Al-doped ZnO films on quartz substrates by radio-frequency magnetron sputtering and effects of thermal annealing

    Energy Technology Data Exchange (ETDEWEB)

    Yang Weifeng [Department of Physics, Xiamen University, Xiamen 361005 (China); Wu Zhengyun, E-mail: zhywu@xmu.edu.c [Department of Physics, Xiamen University, Xiamen 361005 (China); Liu Zhuguang; Pang Aisuo [Department of Physics, Xiamen University, Xiamen 361005 (China); Tu Yuli [Department of Electrical Engineering, National Taiwan University, Taipei 106-17, Taiwan (China); Feng Zhechuan, E-mail: fengzc@cc.ee.ntu.edu.t [Department of Electrical Engineering, National Taiwan University, Taipei 106-17, Taiwan (China)

    2010-10-29

    High-quality Al-doped zinc oxide (AZO) thin films have been deposited on quartz substrates by radio-frequency magnetron sputtering at room temperature for thin film solar cell applications as transparent conductive oxide (TCO) electrode layers. Effects of post-deposition annealing treatment in pure nitrogen and nitrogen/hydrogen atmosphere have been investigated. Annealing treatments were carried out from 300 {sup o}C to 600 {sup o}C for compatibility with typical optoelectronic device fabrication processes. A series of characterization techniques, including X-ray diffraction, scanning electron microscopy, Hall, optical transmission, and X-ray photoelectron spectroscopy has been employed to study these AZO materials. It was found that there were significant changes in crystallinity of the films, resistivity increased from 4.60 x 10{sup -4} to 4.66 x 10{sup -3} {Omega} cm and carrier concentration decreased from 8.68 x 10{sup 20} to 2.77 x 10{sup 20} cm{sup -3} when annealing in 400 {sup o}C pure nitrogen. Whereas there were no significant changes in electrical and optical properties of the AZO films when annealing in 300-500 {sup o}C nitrogen/hydrogen atmosphere, the electrical stability of the AZO films during the hydrogen treatment is attributed to both desorption of adsorbed oxygen from the grain boundaries and production of additional oxygen vacancies that act as donor centers in the films by removal of oxygen from the ZnO matrix. These results demonstrated that the AZO films are stably suited for TCO electrodes in display devices and solar cells.

  17. Fabrication of Ag nanowire and Al-doped ZnO hybrid transparent electrodes

    Science.gov (United States)

    You, Sslimsearom; Park, Yong Seo; Choi, Hyung Wook; Kim, Kyung Hwan

    2016-01-01

    Among the materials used as transparent electrodes, silver nanowires (AgNWs) have attracted attention because of their high transmittance and excellent conductivity. However, AgNWs have shortcomings, including their poor adhesion, oxidation by atmospheric oxygen, and unstable characteristics at high temperature. To overcome these shortcomings, multi-layer thin films with an aluminum-doped zinc oxide (AZO)/AgNW/AZO structure were fabricated using facing targets sputtering. The samples heated to 350 °C exhibited stable electrical characteristics. In addition, the adhesion to the substrate was improved compared with AgNWs layer. The AZO/AgNW/AZO thin films with multilayer structure overcame the shortcomings of AgNWs, and we propose their use as transparent electrodes with excellent properties for optoelectronic applications.

  18. The Influence of α- and γ-Al2O3 Phases on the Thermoelectric Properties of Al-doped ZnO

    DEFF Research Database (Denmark)

    Han, Li; Van Nong, Ngo; Le, Thanh Hung

    2013-01-01

    A systematic investigation on the microstructure and thermoelectric properties of Al-doped ZnO using α- and γ-Al2O3 as dopants was conducted in order to understand the doping effect and its mechanism. The samples were prepared by the spark plasma sintering technique from precursors calcined...... at various temperatures. Clear differences in microstructure and thermoelectric properties were observed between the samples doped with α- and γ-Al2O3. At any given calcination temperature, γ-Al2O3 resulted in the formation of a larger amount of the ZnAl2O4 phase in the Al-doped ZnO samples. The average...... exhibited by these samples. The γ-Al2O3 promoted the substitution for donor impurities in ZnO, thus resulting in shrinkage of the unit cell volume and an increase in the electrical conductivity compared with the α-Al2O3-doped ZnO. At a calcination temperature of 1173K, the γ-Al2O3-doped sample showed a ZT...

  19. Controllable hydrothermal synthesis of ZnO nanowires arrays on Al-doped ZnO seed layer and patterning of ZnO nanowires arrays via surface modification of substrate

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Jin [Electronic Materials Research Laboratory, School of Electronic and Information Engineering, Xi' an Jiaotong University, Xi' an 710049, Shaanxi (China); Que Wenxiu, E-mail: wxque@mail.xjtu.edu.cn [Electronic Materials Research Laboratory, School of Electronic and Information Engineering, Xi' an Jiaotong University, Xi' an 710049, Shaanxi (China); Jia Qiaoying [Electronic Materials Research Laboratory, School of Electronic and Information Engineering, Xi' an Jiaotong University, Xi' an 710049, Shaanxi (China); Ye Xiangdong; Ding Yucheng [State Key Laboratory of Manufacturing Systems Engineering, Xi' an Jiaotong University, Xi' an 710049, Shaanxi (China)

    2011-09-15

    ZnO nanowire (NW) arrays are assembled on the Al-doped ZnO (AZO) seed layer by a hydrothermal process. Effects of the temperature and growth time of the hydrothermal process on morphological and photoluminescence properties of the as-assembled ZnO NW arrays are characterized and studied. Results indicate that the length and diameter of the ZnO NWs increase with a lengthening of the growth time at 80 deg. C and the hydrothermal temperature has a significant effect on the growth rate and the photoluminescence properties of the ZnO NW arrays. The patterned AZO seed layer is fabricated on a silicon substrate by combining a sol-gel process with an electron-beam lithography process, as well as a surface fluorination technique, and then the ZnO NW arrays are selectively grown on those patterned regions of the AZO seed layer by the hydrothermal process. Room-temperature photoluminescence spectra of the patterned ZnO NW arrays shows that only a strong UV emission at about 380 nm is observed, which implies that few crystal defects exist inside the as-grown ZnO NW arrays.

  20. Optical characterization of pure and Al-doped ZnO prepared by sol-gel method

    Science.gov (United States)

    Belka, Radosław; Keczkowska, Justyna; Kasińska, Justyna

    2016-09-01

    In this paper the preparation process and optical characterization of pure and Al3+ doped zinc oxide (Al:ZnO) coatings will be presented. ZnO based materials have been studied extensively due to their potential applications in optoelectronic devices as conductive gas sensors, transparent conductive, electrodes, solar cell windows, varistors, UVfilters or photovoltaic cells. It is II-VI semiconductor with wide-band gap of 3.37 eV and large exciton binding energy of 60meV. It is possible to improve the conductivity of ZnO coating by intentionally doping ZnO with aluminium ions during preparation process. Such transparent and conducting thin films, known as AZO (Aluminium Zinc Oxide) films, are very good candidate for application as transparent conducting materials in many optoelectronic devices. The well-known sol-gel method is used for preparation of solution, coated on glass substrates by dip coating process. Prepared samples were investigated by Raman and UV-VIS spectroscopy. Transmittance as well as specular and diffuse reflectance spectroscopy methods were used for studies of optical parameters. We found that Al admixture influences on optical bandgap of ZnO.

  1. On the variations of optical property and electronic structure in heavily Al-doped ZnO films during double-step growth process

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Q. C.; Ding, K., E-mail: kding@fjirsm.ac.cn; Zhang, J. Y.; Yan, F. P.; Pan, D. M.; Huang, F., E-mail: fhuang@fjirsm.ac.cn [Key Laboratory of Optoelectronic Materials Chemistry and Physics, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002 (China); Chiou, J. W., E-mail: jwchiou@nuk.edu.tw [Department of Applied Physics, National University of Kaohsiung, Kaohsiung 811, Taiwan (China)

    2014-01-13

    We have investigated the variations of optical property and electronic structure in heavily Al-doped ZnO (AZO) films during the growth process, which were formed by first creating Zn vacancies in O{sub 2}-rich atmosphere and second filling the vacancies with Zn atoms in Zn-vapor atmosphere. After the first step, the high-resistance AZO films have the same optical bandgap with nominally undoped ZnO, indicating that negligible variations in the fundamental bandgap happened to the AZO films although Al atom was incorporated into the ZnO lattice. After the second step, once free electrons were brought into the lattice by Zn-filling, the optical transition energy blueshifts due to the band-filling effect. X-ray absorption fine structure measurements suggest that Zn-filling process decreased the unoccupied states of the conduction band, but not raised the conduction band minimum.

  2. Poole-Frenkel effect on electrical characterization of Al-doped ZnO films deposited on p-type GaN

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Bohr-Ran [Graduate Institute of Electro-Optical Engineering and Department of Electronic Engineering, National Taiwan University of Science and Technology, Taipei 106, Taiwan (China); Liao, Chung-Chi [Department of Electronic Engineering, National Taiwan University of Science and Technology, Taipei 106, Taiwan (China); Ke, Wen-Cheng, E-mail: wcke@saturn.yzu.edu.tw; Chang, Yuan-Ching; Huang, Hao-Ping [Department of Mechanical Engineering, Yuan Ze University, Chung-Li 320, Taiwan (China); Chen, Nai-Chuan [Institute of Electro-Optical Engineering and Department of Electronic Engineering, Chang Gung University, Tao-Yuan 333, Taiwan (China)

    2014-03-21

    This paper presents the electrical properties of Al-doped ZnO (AZO) films directly grown on two types of p-type GaN thin films. The low-pressure p-GaN thin films (LP-p-GaN) exhibited structural properties of high-density edge-type threading dislocations (TDs) and compensated defects (i.e., nitrogen vacancy). Compared with high-pressure p-GaN thin films (HP-p-GaN), X-ray photoemission spectroscopy of Ga 3d core levels indicated that the surface Fermi-level shifted toward the higher binding-energy side by approximately 0.7 eV. The high-density edge-type TDs and compensated defects enabled surface Fermi-level shifting above the intrinsic Fermi-level, causing the surface of LP-p-GaN thin films to invert to n-type semiconductor. A highly nonlinear increase in leakage current regarding reverse-bias voltage was observed for AZO/LP-p-GaN. The theoretical fits for the reverse-bias voltage region indicated that the field-assisted thermal ionization of carriers from defect associated traps, which is known as the Poole-Frenkel effect, dominated the I-V behavior of AZO/LP-p-GaN. The fitting result estimated the trap energy level at 0.62 eV below the conduction band edge. In addition, the optical band gap increased from 3.50 eV for as-deposited AZO films to 3.62 eV for 300 °C annealed AZO films because of the increased carrier concentration. The increasing Fermi-level of the 300 °C annealed AZO films enabled the carrier transport to move across the interface into the LP-p-GaN thin films without any thermal activated energy. Thus, the Ohmic behavior of AZO contact can be achieved directly on the low-pressure p-GaN films at room temperature.

  3. Highly (0001)-oriented Al-doped ZnO polycrystalline films on amorphous glass substrates

    Science.gov (United States)

    Nomoto, Junichi; Inaba, Katsuhiko; Osada, Minoru; Kobayashi, Shintaro; Makino, Hisao; Yamamoto, Tetsuya

    2016-09-01

    Very thin aluminum-doped zinc oxide (AZO) films with a well-defined (0001) orientation and a surface roughness of 0.357 nm were deposited on amorphous glass substrates at a temperature of 200 °C by radio frequency magnetron sputtering, which are promising, particularly in terms of orientation evolution, surface roughness, and carrier transport, as buffer layers for the subsequent deposition of highly (0001)-oriented AZO polycrystalline films of 490 nm thickness by direct current (DC) magnetron sputtering. Sintered AZO targets with an Al2O3 content of 2.0 wt. % were used. DC magnetron sputtered AZO films on bare glass substrates showed a mixed (0001) and the others crystallographic orientation, and exhibited a high contribution of grain boundary scattering to carrier transport, resulting in reduced Hall mobility. Optimizing the thickness of the AZO buffer layers to 10 nm led to highly (0001)-oriented bulk AZO films with a marked reduction in the above contribution, resulting in AZO films with improved Hall mobility together with enhanced carrier concentration. The surface morphology and point defect density were also improved by applying the buffer layers, as shown by atomic force microscopy and Raman spectroscopy, respectively.

  4. Deposition of Al doped ZnO layers with various electrical types by atomic layer deposition

    Energy Technology Data Exchange (ETDEWEB)

    Ahn, Cheol Hyoun; Kim, Hyoungsub; Cho, Hyung Koun, E-mail: chohk@skku.ed

    2010-11-01

    AlZnO thin films with various Al/Zn composition ratios were deposited by atomic layer deposition (ALD) at 200 {sup o}C. The effect of the composition of the AlZnO films on their electrical and optical characteristics was investigated. The AlZnO films with an Al content of up to 10 at.% showed high conductivity, while further increasing in the Al content resulted in the abrupt formation of an insulating oxide film. The lowest electrical resistivity of the ALD-deposited AlZnO film was 6.5 x 10{sup -4} [{Omega} cm] at 5 at.% Al. The AlZnO films with up to 5 at.% Al exhibited crystalline phases and a near-band-edge emission. With increasing Al content, the optical band edge showed a blue shift, and a sudden shift associated with an insulating bandgap was observed in the AlZnO films containing 20 at.% Al.

  5. Solution processed Al doped ZnO film fabrication through electrohydrodynamic atomization

    Energy Technology Data Exchange (ETDEWEB)

    Muhammad, Nauman Malik [School of Mechatronics Engineering, Jeju National University, Jeju (Korea, Republic of); Pakistan Atomic Energy Commission, PO-Box, 1114, Islamabad (Pakistan); Duraisamy, Navaneethan [School of Mechatronics Engineering, Jeju National University, Jeju (Korea, Republic of); Dang, Hyun-Woo [School of Electronic Engineering, Jeju National University, Jeju (Korea, Republic of); Jo, Jeongdai [Korea Institute of Machinery and Materials, Daejeon (Korea, Republic of); Choi, Kyung-Hyun, E-mail: amm@jejunu.ac.kr [School of Mechatronics Engineering, Jeju National University, Jeju (Korea, Republic of)

    2012-08-01

    In this study, highly transparent, 250 nm thick films of Aluminum doped Zinc-oxide (ZnO:Al) are achieved on glass substrates at ambient conditions through a solution processing technique called electrohydrodynamic atomization. A 10 wt.% monodispersed solution containing 6% ZnO:Al nanoparticles (ZnO/Al{sub 2}O{sub 3}) in ethanol has been synthesized first and then used in the deposition process as the working solution. Pure and uniform transparent films with an average transmittance of 93% have been deposited with crystal structure exhibiting both zincite and gahnite phases. Surface composition purity has been confirmed using X-ray photoelectron spectroscopy technique and the clear indication of Zn-2p and Al-2p peaks confirms surface integrity. Fourier Transform Infrared analysis further confirms the presence of aluminum in the samples. The electrical properties are studied by recording and analyzing the current-voltage (I-V) measurements and the resistivity has been estimated from the slope of the IV-curve which is approximately 25 m{Omega}.cm. The layer roughness has been characterized using atomic force microscopy. - Highlights: Black-Right-Pointing-Pointer Aluminum doped Zinc oxide (ZnO:Al) films are made via electrohydrodynamic atomization. Black-Right-Pointing-Pointer ZnO:Al nano-particle ink is used to form thin films in single step at room conditions. Black-Right-Pointing-Pointer Scanning electron and atomic force microscopes confirm fine layer characteristics. Black-Right-Pointing-Pointer X-ray photoelectron and Fourier Transform-Infrared spectroscope confirm film purity. Black-Right-Pointing-Pointer Transparent and conductive films have been fabricated with wurtzite structure.

  6. Interfacially Al-doped ZnO nanowires: greatly enhanced near band edge emission through suppressed electron-phonon coupling and confined optical field.

    Science.gov (United States)

    Wu, Yiming; Dai, Yanmeng; Jiang, Shenlong; Ma, Chao; Lin, Yue; Du, Dongxue; Wu, Yukun; Ding, Huaiyi; Zhang, Qun; Pan, Nan; Wang, Xiaoping

    2017-04-05

    Aluminium (Al)-doped zinc oxide (ZnO) nanowires (NWs) with a unique core-shell structure and a Δ-doping profile at the interface were successfully grown using a combination of chemical vapor deposition re-growth and few-layer AlxOy atomic layer deposition. Unlike the conventional heavy doping which degrades the near-band-edge (NBE) luminescence and increases the electron-phonon coupling (EPC), it was found that there was an over 20-fold enhanced NBE emission and a notably-weakened EPC in this type of interfacially Al-doped ZnO NWs. Further experiments revealed a greatly suppressed nonradiative decay process and a much enhanced radiative recombination rate. By comparing the finite-difference time-domain simulation with the experimental results from intentionally designed different NWs, this enhanced radiative decay rate was attributed to the Purcell effect induced by the confined and intensified optical field within the interfacial layer. The ability to manipulate the confinement, transport and relaxation dynamics of ZnO excitons can be naturally guaranteed with this unique interfacial Δ-doping strategy, which is certainly desirable for the applications using ZnO-based nano-photonic and nano-optoelectronic devices.

  7. CdS/CdSe-sensitized solar cell based on Al-doped ZnO nanoparticles prepared by the decomposition of zinc acetate solid solution

    Science.gov (United States)

    Deng, Jianping; Wang, Minqiang; Ye, Wei; Fang, Junfei; Zhang, Pengchao; Yang, Yongping; Yang, Zhi

    2017-01-01

    In the study, Al-doped ZnO nanoparticles (Al-ZnO NPs) were prepared by the decomposition of zinc acetate solid solution. The X-ray diffraction results showed that Al3+ was successfully doped without the formation of Al and Al2O3 impurity phases. The less Al-doping did not change the hexagonal wurtzite crystal structure of ZnO. The ratio of Al to Al + Zn (9.05%) measured by the energy dispersive X-ray also confirmed the formation of Al-ZnO. The Al-ZnO NPs were used as the photoanode material to prepare CdS/CdSe-sensitized solar cell. Compared with the cell based on commercial ZnO NPs (C-ZnO), the short-circuit current density and the fill factor of the cell were increased from 5.8 mA/cm2 and 34.1% (C-ZnO) to 7.78 mA/cm2 and 48.7% (Al-ZnO), respectively. The cell efficiency was increased from 1.01% (C-ZnO) to (1.9%) (Al-ZnO) and the increase percentage reached 88.1%. The results of electrochemical impedance spectroscopy and open-circuit voltage-decay suggested the lower carrier transport resistance and the longer electron lifetime of Al-ZnO-based cell.

  8. Arrays of ZnO/AZO (Al-doped ZnO) nanocables: a higher open circuit voltage and remarkable improvement of efficiency for CdS-sensitized solar cells.

    Science.gov (United States)

    Deng, Jianping; Wang, Minqiang; Liu, Jing; Song, Xiaohui; Yang, Zhi

    2014-03-15

    Photoelectrode of nanocables (NCs) structure of ZnO nanowires (NWs) coated with Al-doped ZnO (AZO) shells was investigated for CdS quantum dots sensitized solar cells (QDSSCs). ZnO NWs serve as the frame for the preparation of AZO shells, in which electron transport more rapidly due to the more higher electron mobility of AZO (n-ZnO) than that of i-ZnO. AZO shells were assembled onto the surface of ZnO NWs via a spin-coating method. Optical band-gap of the ZnO/AZO films varies from 3.19 eV for pure ZnO to 3.25 eV for AZO (15%) depending on the Al-doping concentration. The PL intensity of AZO/ZnO, V(oc), J(sc) and η of the cells first increased and then decreased with the increase in the Al-doping (from 0% to 20%) and post-annealed temperature. Remarkably, the value of V(oc) can achieve above 0.8 V after Al-doping. The dark current and absorption spectrum provided direct evidence of the increase in J(sc) and V(oc), respectively. Moreover, we discussed the effect of Al-doping on optical band-gap of the samples and the transfer of electron.

  9. Field-induced doping-mediated tunability in work function of Al-doped ZnO: Kelvin probe force microscopy and first-principle theory

    Science.gov (United States)

    Kumar, Mohit; Mookerjee, Sumit; Som, Tapobrata

    2016-09-01

    We demonstrate that the work function of Al-doped ZnO (AZO) can be tuned externally by applying an electric field. Our experimental investigations using Kelvin probe force microscopy show that by applying a positive or negative tip bias, the work function of AZO film can be enhanced or reduced, which corroborates well with the observed charge transport using conductive atomic force microscopy. These findings are further confirmed by calculations based on first-principles theory. Tuning the work function of AZO by applying an external electric field is not only important to control the charge transport across it, but also to design an Ohmic contact for advanced functional devices.

  10. Field-induced doping-mediated tunability in work function of Al-doped ZnO: Kelvin probe force microscopy and first-principle theory.

    Science.gov (United States)

    Kumar, Mohit; Mookerjee, Sumit; Som, Tapobrata

    2016-09-16

    We demonstrate that the work function of Al-doped ZnO (AZO) can be tuned externally by applying an electric field. Our experimental investigations using Kelvin probe force microscopy show that by applying a positive or negative tip bias, the work function of AZO film can be enhanced or reduced, which corroborates well with the observed charge transport using conductive atomic force microscopy. These findings are further confirmed by calculations based on first-principles theory. Tuning the work function of AZO by applying an external electric field is not only important to control the charge transport across it, but also to design an Ohmic contact for advanced functional devices.

  11. Structural and X-Ray Photoelectron Spectroscopy Study of Al-Doped Zinc-Oxide Thin Films

    Directory of Open Access Journals (Sweden)

    Bong Ju Lee

    2015-01-01

    Full Text Available Al-doped zinc-oxide (AZO thin films were prepared by RF magnetron sputtering at different oxygen partial pressures and substrate temperatures. The charge-carrier concentrations in the films decreased from 1.69 × 1021 to 6.16 × 1017 cm−3 with increased gas flow rate from 7 to 21 sccm. The X-ray diffraction (XRD patterns show that the (002/(103 peak-intensity ratio decreased as the gas flow rate increased, which was related to the increase of AZO thin film disorder. X-ray photoelectron spectra (XPS of the O1s were decomposed into metal oxide component (peak A and the adsorbed molecular oxygen on thin films (peak B. The area ratio of XPS peaks (A/B was clearly related to the stoichiometry of AZO films; that is, the higher value of A/B showed the higher stoichiometric properties.

  12. Effect of aluminium doping on structural and optical properties of ZnO thin films by sol-gel method

    Energy Technology Data Exchange (ETDEWEB)

    Vijayaprasath, G.; Murugan, R.; Ravi, G., E-mail: raviganesa@rediffmail.com, E-mail: gravicrc@gmail.com [Department of Physics, Alagappa University, Karaikudi – 630003 (India); Hayakawa, Y. [Research Institute of Electronics, Shizuoka University, Hamamatsu 432-8011 (Japan)

    2015-06-24

    We systematically investigated the structural, morphological and optical properties of 0.05 mol % Al doped ZnO (Al:ZnO) thin films deposited on glass substrates by sol-gel spin coating method. The influences of Al doping in ZnO thin films are characterized by Powder X-ray diffraction study. ZnO and Al:ZnO thin films have showed hexagonal wurtzite structure without any secondary phase in c-axis (002) orientation. The SEM images also proved the hexagonal rod like morphologies for both films. All the films exhibited transmittance of 70-80% in the visible range up to 800 nm and cut-off wavelength observed at ∼390 nm corresponding to the fundamental absorption of ZnO. The band gap of the ZnO thin films slightly widened with the Al doping. The photoluminescence properties have been studied for Al: ZnO thin films and the results are presented in detail.

  13. Improved performance of organic light-emitting diodes fabricated on Al-doped ZnO anodes incorporating a homogeneous Al-doped ZnO buffer layer grown by atomic layer deposition.

    Science.gov (United States)

    Choi, Yong-June; Gong, Su Cheol; Park, Chang-Sun; Lee, Hong-Sub; Jang, Ji Geun; Chang, Ho Jung; Yeom, Geun Young; Park, Hyung-Ho

    2013-05-01

    In this work, we investigated the use of a homogeneous Al-doped zinc oxide (AZO) buffer layer to improve the performance of an organic light-emitting diode (OLED) device fabricated on an AZO anode. For this, 10-nm-thick AZO buffer layers with Al doping concentrations of 3.1, 4.1, and 5.1 at % were grown on 140-nm-thick AZO anode films containing 2.1 at % Al by atomic layer deposition. The electrical resistivity of the AZO anode with a homogeneous AZO buffer layer decreased with an increase in Al doping concentration up to 4.1 at %; however, the resistivity increased at higher doping concentrations in the AZO buffer layer. On the other hand, the work functions of the AZO anode with the AZO buffer layer containing various Al doping concentrations gradually increased with an increase in Al doping concentration from 3.1 to 5.1 at %. Therefore, the best film properties were obtained for an AZO anode with an AZO buffer layer containing 4.1 at % Al, and the work function value for this film was 4.64 eV. The highest luminance and current efficiency values were optimized to be 20290 cd/m(2) and 13.4 cd/A, respectively, with the OLED device composed of a DNTPD/TAPC/Bebq2:10% doped RP-411/Bphen/LiF/Al structure on an AZO anode with an AZO buffer layer containing 4.1 at % Al.

  14. Pressurized polyol synthesis of Al-doped ZnO nanoclusters with high electrical conductivity and low near-infrared transmittance

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Ho-Nyun; Shin, Chi-Ho [Surface Technology R& BD Group, Korea Institute of Industrial Technology (KITECH), Incheon 406-840 (Korea, Republic of); Hwang, Duck Kun [Department of Corporate Diagnosis, Small and Medium Business Corporation, Seoul 150-718 (Korea, Republic of); Kim, Haekyoung [School of Materials Science and Engineering, Yeungnam University, Gyeongsan 712-749 (Korea, Republic of); Oh, Kyeongseok [Department of Chemical and Environmental Technology, Inha Technical College, Incheon 402-752 (Korea, Republic of); Kim, Hyun-Jong, E-mail: hjkim23@kitech.re.kr [Surface Technology R& BD Group, Korea Institute of Industrial Technology (KITECH), Incheon 406-840 (Korea, Republic of)

    2015-09-25

    Highlights: • Low-temperature pressurized polyol method synthesized Al-doped ZnO nanoclusters. • Reaction time affected the doping efficiency, resistivity, and NIR transmittance. • The near-IR blocking efficiency of Al-doped ZnO (AZO) nanoclusters reached 85%. • AZO nanocluster coatings could be used for heat reflectors or artificial glasses. - Abstract: In this study, a novel pressurized polyol method is proposed to synthesize aluminum-doped ZnO (AZO) nanoclusters without utilizing additional thermal treatment to avoid the merging of nanoclusters. The size of the AZO nanoclusters range from 100 to 150 nm with a resistivity of 204 Ω cm. The AZO nanoclusters primarily consist of approximately 10-nm nanocrystals that form a spherically clustered morphology. A two-stage growth model has been proposed based on the results of scanning electron microscopy and transmission electron microscopy images, nanocluster sizes, and X-ray diffraction patterns. The primary AZO nanocrystals first nucleate under pressurized conditions and then spontaneously aggregate into larger nanoclusters. Optically, the AZO nanoclusters exhibit a significant decrease in the near-infrared (NIR) transmittance compared to pure ZnO nanoparticles. The NIR blocking efficiency of AZO nanoclusters reached 85%. Moreover, the doping efficiency, resistivity, and NIR transmittance of AZO nanoclusters are influenced by the reaction time in the pressurized polyol solution. On the other hand, the reaction time has no effect on the particle size and crystallinity. An optically transparent coating for the AZO nanoclusters, which consisted of iso-propanol solvent and ultraviolet-curable acrylic binder, was also demonstrated.

  15. Effect of Al Doping on Optical Band Gap Energy of Al-TiO2 Thin Films.

    Science.gov (United States)

    Song, Yo-Seung; Kim, Bae-Yeon; Cho, Nam-Ihn; Lee, Deuk Yong

    2015-07-01

    Al-TiO2 thin films were prepared using a sol-gel derived spin coating by varying the Al/Ti molar ratio from 0 to 0.73 to investigate the effect of Al doping on the optical band gap energy (Eg) of the films. GAXRD results indicated that Al-TiO2 is composed of anatase and FTO phases when the Al/Ti molar ratio was less than 0.18. Above 0.38, no other peaks except FTO were found and transparency of the films was severely deteriorated. Eg of Al-TiO2 decreased from 3.20 eV to 2.07 eV when the Al/Ti ratio was raised from 0 to 0.38. Eg of 2.59 eV was found for the anatase Al-TiO2 films having the Al/Ti ratio of 0.18. The absorption band of Al-TiO2 coatings shifted dramatically from the UV region to the visible region with increasing the amount of Al dopant. The Al doping was mainly attributed to the optical band gap energy of Al-TiO2.

  16. Pure and Al-doped ZnO obtained by the modified Pechini method applied in ethanolic transesterification of cottonseed oil

    Energy Technology Data Exchange (ETDEWEB)

    Pereira, M.F.; Silva-Neta, A.R.; Farias, A.F.F.; Souza, A.G.; Fonseca, M.G.; Pontes, L.F.B.L.; Santos, I.M.G., E-mail: ieda.garcia@pq.cnpq.br [Universidade Federal da Paraiba (LACOM/UFPB), Joao Pessoa, PB (Brazil). Dept. de Quimica

    2017-01-15

    Pure zinc oxide (ZnO) and 5% Al-doped ZnO (ZNAL) were synthesized using the modified Pechini method and characterized by X-ray diffraction (XRD), X-ray fluorescence (XRF), Raman spectroscopy, infrared spectroscopy and UV-visible spectroscopy. XRF confirmed the theoretical stoichiometry, while XRD and Raman spectroscopy indicated that Al{sup 3+} was incorporated into the ZnO wurtzite lattice with no secondary phases, leading to a decrease in the band gap value and to a meaningful increase of the Lewis basic sites. Pure and doped ZnO were used as catalysts in the ethylic transesterification of cottonseed oil using a factorial design to determine the best synthesis conditions. Oil conversion into biodiesel was evaluated by viscosity measurements and {sup 1}H NMR spectroscopy. The results analyzed by factorial design indicated that the catalyst type and temperature were the determinant factors in the conversion indices. The highest basicity of the ZNAL lead to a significant increase of the catalytic potential, reaching a reduction of the oil viscosity next to 71% at 130 °C and greater than 85% at 200 °C. (author)

  17. Study on the enhanced and stable field emission behavior of a novel electrosprayed Al-doped ZnO bilayer film

    KAUST Repository

    Mahmood, Khalid

    2014-01-01

    A novel electrosprayed bilayer film composed of an over-layer (L 2) of aluminium-doped ZnO (AZO) nanoflakes (NF-AZO) and a under-layer (L1) of AZO nanocrystallites structure (NC-AZO) named BL:NF/NC-AZO is studied as an excellent field-emitter. The XRD pattern demonstrated that the doped bilayer film has preferential growth along the c-axis with hexagonal wurtzite structure and the (0 0 2) peak shifted toward the larger angle side after doping. The lowest turn-on field of ∼2.8 V μm-1, highest emission current density of 1.95 mA cm-2 is obtained for BL:NF/NC-AZO under the field of 6.8 V μm-1 and as well as the highest field enhancement factor (β) is estimated to be 4370 ± 3, compared to pure ZnO bilayer film (BL:NF/NC-ZnO) and also better than NC-AZO film and possesses the excellent long term stability of emission current. The PL intensity of doped ZnO bilayer film is very much stronger than pure ZnO bilayer structure. The superior field emission properties are attributed to the better morphologies, Al-doping and better crystallinity of bilayer AZO films. © 2014 The Royal Society of Chemistry.

  18. Enhanced p-type conductivity and band gap narrowing in heavily Al doped NiO thin films deposited by RF magnetron sputtering.

    Science.gov (United States)

    Nandy, S; Maiti, U N; Ghosh, C K; Chattopadhyay, K K

    2009-03-18

    Stoichiometric NiO, a Mott-Hubbard insulator at room temperature, shows p-type electrical conduction due to the introduction of Ni(2+) vacancies (V(Ni)('')) and self-doping of Ni(3+) ions in the presence of excess oxygen. The electrical conductivity of this important material is low and not sufficient for active device fabrication. Al doped NiO thin films were synthesized by radio frequency (RF) magnetron sputtering on glass substrates at a substrate temperature of 250 °C in an oxygen + argon atmosphere in order to enhance the p-type electrical conductivity. X-ray diffraction studies confirmed the correct phase formation and also oriented growth of NiO thin films. Al doping was confirmed by x-ray photoelectron spectroscopic studies. The structural, electrical and optical properties of the films were investigated as a function of Al doping (0-4 wt%) in the target. The room temperature electrical conductivity increased from 0.01-0.32 S cm (-1) for 0-4% Al doping. With increasing Al doping, above the Mott critical carrier density, energy band gap shrinkage was observed. This was explained by the shift of the band edges due to the existence of exchange and correlation energies amongst the electron-electron and hole-hole systems and also by the interaction between the impurity quasi-particle system.

  19. Controllable synthesis of flake-like Al-doped ZnO nanostructures and its application in inverted organic solar cells.

    Science.gov (United States)

    Fan, Xi; Fang, Guojia; Guo, Shishang; Liu, Nishuang; Gao, Huimin; Qin, Pingli; Li, Songzhan; Long, Hao; Zheng, Qiao; Zhao, Xingzhong

    2011-10-04

    Flake-like Al-doped ZnO (AZO) nanostructures including dense AZO nanorods were obtained via a low-temperature (100°C) hydrothermal process. By doping and varying Al concentrations, the electrical conductivity (σ) and morphology of the AZO nanostructures can be readily controlled. The effect of σ and morphology of the AZO nanostructures on the performance of the inverted organic solar cells (IOSCs) was studied. It presents that the optimized power conversion efficiency of the AZO-based IOSCs is improved by approximately 58.7% compared with that of un-doped ZnO-based IOSCs. This is attributed to that the flake-like AZO nanostructures of high σ and tunable morphology not only provide a high-conduction pathway to facilitate electron transport but also lead to a large interfacial area for exciton dissociation and charge collection by electrodes.

  20. Controllable synthesis of flake-like Al-doped ZnO nanostructures and its application in inverted organic solar cells

    Directory of Open Access Journals (Sweden)

    Fan Xi

    2011-01-01

    Full Text Available Abstract Flake-like Al-doped ZnO (AZO nanostructures including dense AZO nanorods were obtained via a low-temperature (100°C hydrothermal process. By doping and varying Al concentrations, the electrical conductivity (σ and morphology of the AZO nanostructures can be readily controlled. The effect of σ and morphology of the AZO nanostructures on the performance of the inverted organic solar cells (IOSCs was studied. It presents that the optimized power conversion efficiency of the AZO-based IOSCs is improved by approximately 58.7% compared with that of un-doped ZnO-based IOSCs. This is attributed to that the flake-like AZO nanostructures of high σ and tunable morphology not only provide a high-conduction pathway to facilitate electron transport but also lead to a large interfacial area for exciton dissociation and charge collection by electrodes.

  1. Improvement of GaN light-emitting diodes with surface-treated Al-doped ZnO transparent Ohmic contacts by holographic photonic crystal

    Energy Technology Data Exchange (ETDEWEB)

    Yang, W.F. [Xiamen University, Department of Physics, Xiamen (China); National University of Singapore, Department of Materials Science and Engineering, Singapore (Singapore); Liu, Z.G.; Xie, Y.N.; Cai, J.F.; Liu, S.; Wu, Z.Y. [Xiamen University, Department of Physics, Xiamen (China); Gong, H. [National University of Singapore, Department of Materials Science and Engineering, Singapore (Singapore)

    2012-06-15

    This letter presents a holographic photonic crystal (H-PhC) Al-doped ZnO (AZO) transparent Ohmic contact layer on p-GaN to increase the light output of GaN-based LEDs without destroying the p-GaN. The operating voltage of the PhC LEDs at 20 mA was almost the same as that of the typical planar AZO LEDs. While the resultant PhC LED devices exhibited significant improvements in light extraction, up to 1.22 times that of planar AZO LEDs without PhC integration. Temperature dependence of the integrated photoluminescence intensity indicates that this improvement can be attributed to the increased extraction efficiency due to the surface modification. These results demonstrate that the surface-treated AZO layer by H-PhCs is suitable for fabricating high-brightness GaN-based LEDs. (orig.)

  2. Improved broadband antireflection in Schottky-like junction of conformal Al-doped ZnO layer on chemically textured Si surfaces

    Science.gov (United States)

    Saini, C. P.; Barman, A.; Kumar, M.; Sahoo, P. K.; Som, T.; Kanjilal, A.

    2014-09-01

    Chemically textured Si with improved absorption in the complete range of solar spectrum is investigated by ultraviolet/visible/near-infrared (UV/Vis/NIR) spectroscopy, showing an average specular reflectance of ˜0.4% in the wavelength of 500-3000 nm. The pyramidal structures on such solar-blind Si can reduce the reflectance further below 0.1% in the UV region by conformal growth of granular Al-doped ZnO (AZO) films. X-ray diffraction analyses suggest the growth of polycrystalline AZO on faceted-Si. Moreover, marginal increase in electrical conductivity of AZO is found on textured surfaces, whereas rise in leakage current in Schottky-like Ag/AZO/Si/Ag heterostructure devices is noticed with increasing Si surface area.

  3. Al-doping effects on the photovoltaic performance of inverted polymer solar cells

    Science.gov (United States)

    Yu, Xuan; Shi, Ya-feng; Yu, Xiao-ming; Zhang, Jian-jun; Ge, Ya-ming; Chen, Li-qiao; Pan, Hong-jun

    2016-03-01

    The properties of Al-doped ZnO (AZO) play an important role in the photovoltaic performance of inverted polymer solar cells (PSCs), which is used as electron transport and hole blocking buffer layers. In this work, we study the effects of Al-doping level in AZO on device performance in detail. Results indicate that the device performance intensely depends on the Al-doping level. The AZO thin films with Al-doping atomic percentage of 1.0% possess the best conductivity. The resulting solar cells show the enhanced short current density and the fill factor ( FF) simultaneously, and the power conversion efficiency ( PCE) is improved by 74%, which are attributed to the reduced carrier recombination and the optimized charge transport and extraction between AZO and the active layer.

  4. High-Hall-Mobility Al-Doped ZnO Films Having Textured Polycrystalline Structure with a Well-Defined (0001) Orientation.

    Science.gov (United States)

    Nomoto, Junichi; Makino, Hisao; Yamamoto, Tetsuya

    2016-12-01

    Five hundred-nanometer-thick ZnO-based textured polycrystalline films consisting of 490-nm-thick Al-doped ZnO (AZO) films deposited on 10-nm-thick Ga-doped ZnO (GZO) films exhibited a high Hall mobility (μ H) of 50.1 cm(2)/Vs with a carrier concentration (N) of 2.55 × 10(20) cm(-3). Firstly, the GZO films were prepared on glass substrates by ion plating with dc arc discharge, and the AZO films were then deposited on the GZO films by direct current magnetron sputtering (DC-MS). The GZO interface layers with a preferential c-axis orientation play a critical role in producing AZO films with texture development of a well-defined (0001) orientation, whereas 500-nm-thick AZO films deposited by only DC-MS showed a mixture of the c-plane and the other plane orientation, to exhibit a μ H of 38.7 cm(2)/Vs with an N of 2.22 × 10(20) cm(-3).

  5. Thickness Effect of Al-Doped ZnO Window Layer on Damp-Heat Stability of CuInGaSe2 Solar Cells

    Energy Technology Data Exchange (ETDEWEB)

    Pern, F. J.; Mansfield, L.; DeHart, C.; Glick, S. H.; Yan, F.; Noufi, R.

    2011-01-01

    We investigated the damp heat (DH) stability of CuInGaSe{sub 2} (CIGS) solar cells as a function of thickness of the Al-doped ZnO (AZO) window layer from the 'standard' 0.12 {micro}m to a modest 0.50 {micro}m over an underlying 0.10-{micro}m intrinsic ZnO buffer layer. The CIGS cells were prepared with external electrical contact using fine Au wire to the tiny 'standard' Ni/Al (0.05 {micro}m/3 {micro}m) metal grid contact pads. Bare cell coupons and sample sets encapsulated in a specially designed, Al-frame test structure with an opening for moisture ingress control using a TPT backsheet were exposed to DH at 85 C and 85% relative humidity, and characterized by current-voltage (I-V), quantum efficiency (QE), and (electrochemical) impedance spectroscopy (ECIS). The results show that bare cells exhibited rapid degradation within 50-100 h, accompanied by film wrinkling and delamination and corrosion of Mo and AlNi grid, regardless of AZO thickness. In contrast, the encapsulated cells did not show film wrinkling, delamination, and Mo corrosion after 168 h DH exposure; but the trend of efficiency degradation rate showed a weak correlation to the AZO thickness.

  6. Thickness Effect of Al-Doped ZnO Window Layer on Damp Heat Stability of CuInGaSe2 Solar Cells: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Pern, F. J.; Mansfield, L.; DeHart, C.; Glick, S. H.; Yan, F.; Noufi, R.

    2011-07-01

    We investigated the damp heat (DH) stability of CuInGaSe2 (CIGS) solar cells as a function of thickness of the Al-doped ZnO (AZO) window layer from the 'standard' 0.12 μm to a modest 0.50 μm over an underlying 0.10-μm intrinsic ZnO buffer layer. The CIGS cells were prepared with external electrical contact using fine Au wire to the tiny 'standard' Ni/Al (0.05 μm/3 μm) metal grid contact pads. Bare cell coupons and sample sets encapsulated in a specially designed, Al-frame test structure with an opening for moisture ingress control using a TPT backsheet were exposed to DH at 85oC and 85% relative humidity, and characterized by current-voltage (I-V), quantum efficiency (QE), and (electrochemical) impedance spectroscopy (ECIS). The results show that bare cells exhibited rapid degradation within 50-100 h, accompanied by film wrinkling and delamination and corrosion of Mo and AlNi grid, regardless of AZO thickness. In contrast, the encapsulated cells did not show film wrinkling, delamination, and Mo corrosion after 168 h DH exposure; but the trend of efficiency degradation rate showed a weak correlation to the AZO thickness.

  7. High-Hall-Mobility Al-Doped ZnO Films Having Textured Polycrystalline Structure with a Well-Defined (0001) Orientation

    Science.gov (United States)

    Nomoto, Junichi; Makino, Hisao; Yamamoto, Tetsuya

    2016-06-01

    Five hundred-nanometer-thick ZnO-based textured polycrystalline films consisting of 490-nm-thick Al-doped ZnO (AZO) films deposited on 10-nm-thick Ga-doped ZnO (GZO) films exhibited a high Hall mobility ( μ H) of 50.1 cm2/Vs with a carrier concentration ( N) of 2.55 × 1020 cm-3. Firstly, the GZO films were prepared on glass substrates by ion plating with dc arc discharge, and the AZO films were then deposited on the GZO films by direct current magnetron sputtering (DC-MS). The GZO interface layers with a preferential c-axis orientation play a critical role in producing AZO films with texture development of a well-defined (0001) orientation, whereas 500-nm-thick AZO films deposited by only DC-MS showed a mixture of the c-plane and the other plane orientation, to exhibit a μ H of 38.7 cm2/Vs with an N of 2.22 × 1020 cm-3.

  8. Optical measurements and mapping in Ga- and Al-doped ZnO and Sn-doped In{sub 2}O{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Look, D.C. [Semiconductor Research Center, Wright State University, Dayton, OH, 45435 (United States); Wyle Laboratories, Inc., 2601 Mission Point Boulevard, Suite 300, Dayton, OH, 45431 (United States); Air Force Research Laboratory Sensors Directorate, Wright-Patterson Air Force Base, OH, 45433 (United States); Leedy, K.D. [Air Force Research Laboratory Sensors Directorate, Wright-Patterson Air Force Base, OH, 45433 (United States)

    2015-07-15

    Hall-effect/conductivity measurements in TCO materials such as Ga-doped ZnO (GZO), Al-doped ZnO (AZO), and Sn-doped In{sub 2}O{sub 3} (ITO) determine Hall mobility μ{sub H} and sheet carrier concentration n{sub s} directly by measurements of current, voltage, and magnetic field. If thickness d is known, then n{sub s} can be converted into volume concentration n = n{sub s}/d. Optical measurements, on the other hand, determine analogous quantities μ{sub opt} and n{sub opt} indirectly, usually by invoking the Drude model of the dielectric constant. Here we compare μ{sub opt} and n{sub opt} obtained by Drude analysis of reflection, transmission, and spectroscopic-ellipsometry (SE) measurements, with μ{sub H} and n. Although reasonably good agreement between Hall effect and optical parameters can be obtained with all of these techniques, SE is especially attractive for non-destructive, high-density mapping of μ and n. Moreover, we can use degenerate scattering theory to convert maps of μ and n into maps of donor and acceptor concentration. This new mapping methodology is applied to GZO and ITO. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  9. Effect of Al-doped ZnO or Sn-doped In2O3 electrode on ferroelectric properties of (Pb,La)(Zr,Ti)O3 capacitors

    Science.gov (United States)

    Takada, Yoko; Tsuji, Toru; Okamoto, Naoki; Saito, Takeyasu; Kondo, Kazuo; Yoshimura, Takeshi; Fujimura, Norifumi; Higuchi, Koji; Kitajima, Akira; Iwai, Hideo

    2015-05-01

    Using chemical solution deposition, we fabricated ferroelectric (Pb,La)(Zr,Ti)O3 (PLZT) capacitors with either Al-doped ZnO (AZO) or Sn-doped In2O3 (ITO) top electrodes. Then, the effects of a thin conductive AZO or ITO buffer layer between the Pt bottom electrode and PLZT thin film were investigated in combination with an AZO or ITO top electrode (AZO/PLZT/AZO/Pt and ITO/PLZT/ITO/Pt). The H2 degradation resistance of the AZO/PLZT/AZO/Pt and ITO/PLZT/ITO/Pt capacitors was improved. For AZO/PLZT/AZO/Pt capacitors with 10- and 20-nm-thick buffer layers, the H2 degradation resistance was 91 and 81%, respectively, compared with 42-70% without a buffer layer. The H2 degradation resistance of ITO/PLZT/ITO/Pt capacitors with a 28-nm-thick buffer layer was improved to 85% from 60-76% without a buffer layer. The time-of-flight secondary ion mass spectrometry depth profile indicated that AZO is the better H2 barrier after forming gas (3% H2/balance N2) annealing.

  10. Improved photovoltaic performance of inverted polymer solar cells through a sol-gel processed Al-doped ZnO electron extraction layer.

    Science.gov (United States)

    Kim, Jun Young; Cho, Eunae; Kim, Jaehoon; Shin, Hyeonwoo; Roh, Jeongkyun; Thambidurai, Mariyappan; Kang, Chan-mo; Song, Hyung-Jun; Kim, SeongMin; Kim, Hyeok; Lee, Changhee

    2015-09-21

    We demonstrate that nanocrystalline Al-doped zinc oxide (n-AZO) thin film used as an electron-extraction layer can significantly enhance the performance of inverted polymer solar cells based on the bulk heterojunction of poly[[9-(1-octylnonyl)-9H-carbazole-2,7-diyl]-2,5-thiophenediyl-2,1,3-benzothiadiazole-4,7-diyl-2,5-thiophenediyl] (PCDTBT) and [6,6]-phenyl C(71)-butyric acid methyl ester (PC(70)BM). A synergistic study with both simulation and experiment on n-AZO was carried out to offer a rational guidance for the efficiency improvement. As a result, An n-AZO film with an average grain size of 13 to 22 nm was prepared by a sol-gel spin-coating method, and a minimum resistivity of 2.1 × 10(-3) Ω·cm was obtained for an Al-doping concentration of 5.83 at.%. When an n-AZO film with a 5.83 at.% Al concentration was inserted between the ITO electrode and the active layer (PCDTBT:PC(70)BM), the power conversion efficiency increased from 3.7 to 5.6%.

  11. Flexible Al-doped ZnO films grown on PET substrates using linear facing target sputtering for flexible OLEDs

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, Jin-A; Shin, Hyun-Su; Choi, Kwang-Hyuk; Kim, Han-Ki, E-mail: imdlhkkim@khu.ac.k [Information Materials and Device Laboratory (IMDL), Department of Advanced Materials Engineering for Information and Electronics, Kyung Hee University, 1 Seocheon-dong, Yongin-si, Gyeonggi-do, 446-701 (Korea, Republic of)

    2010-11-24

    We report the characteristics of flexible Al-doped zinc oxide (AZO) films prepared by a plasma damage-free linear facing target sputtering (LFTS) system on PET substrates for use as a flexible transparent conducting electrode in flexible organic light-emitting diodes (OLEDs). The electrical, optical and structural properties of LFTS-grown flexible AZO electrodes were investigated as a function of dc power. We obtained a flexible AZO film with a sheet resistance of 39 {Omega}/{open_square} and an average transmittance of 84.86% in the visible range although it was sputtered at room temperature without activation of the Al dopant. Due to the effective confinement of the high-density plasma between the facing AZO targets, the AZO film was deposited on the PET substrate without plasma damage and substrate heating caused by bombardment of energy particles. Moreover, the flexible OLED fabricated on the AZO/PET substrate showed performance similar to the OLED fabricated on a ITO/PET substrate in spite of a lower work function. This indicates that LFTS is a promising plasma damage-free and low-temperature sputtering technique for deposition of flexible and indium-free AZO electrodes for use in cost-efficient flexible OLEDs.

  12. Thin films of conductive ZnO patterned by micromolding resulting in nearly isolated features.

    Science.gov (United States)

    Göbel, Ole F; Blank, Dave H A; ten Elshof, Johan E

    2010-02-01

    Patterned and continuous thin films of conductive Al-doped zinc oxide (ZnO:Al) were prepared on different substrates from a polymeric precursor solution. Their electric conductivity and light transmittance (for visible and UV light) was measured at room temperature. By means of a simple device, conductive ZnO:Al films with high fidelity patterns with features of 2-20 microm width could be obtained by simply micromolding the liquid precursor film prior to heat treatment. The individual features were interconnected by a very thin residual ZnO layer.

  13. Defect analysis by transmission electron microscopy of epitaxial Al-doped ZnO films grown on (0001) ZnO and a-sapphire by RF magnetron sputtering

    Science.gov (United States)

    Rengachari, Mythili; Bikowski, André; Ellmer, Klaus

    2016-07-01

    Microstructural investigations by cross section Transmission Electron Microscopy have been carried out on Al-doped ZnO films epitaxially grown on (0001) ZnO and a-sapphire by RF magnetron sputtering, since it is known that crystallographic defects influence the physical properties of ZnO films. Threading dislocations and basal stacking faults were the predominant defects observed in these films, which were dependent on the type of the substrate and its orientation. The orientational relationship between the ZnO:Al film and the a-sapphire was determined to be ( 11 2 ¯ 0 )sapphire||(0001)ZnO:Al and [0001]sapphire||[ 11 2 ¯ 0 ]ZnO:Al. The density of dislocations in the heteroepitaxial film of ZnO:Al on a-sapphire was higher than that of the homoepitaxial film of ZnO:Al on undoped ZnO, due to the difference in the lattice mismatch, which also affected the crystallinity of the film.

  14. Enhanced Doping Efficiency of Al-Doped ZnO by Atomic Layer Deposition Using Dimethylaluminum Isopropoxide as an Alternative Aluminum Precursor

    NARCIS (Netherlands)

    Wu, Y.; Potts, S.E.; Hermkens, P.M.; Knoops, H.C.M.; Roozeboom, F.; Kessels, W.M.M.

    2013-01-01

    Atomic layer deposition offers the unique opportunity to control, at the atomic level, the 3D distribution of dopants in highly uniform and conformal thin films. Here, it is demonstrated that the maximum doping efficiency of Al in ZnO can be improved from ∼10% to almost 60% using dimethylaluminum is

  15. AlGaN/GaN high-electron-mobility transistors with transparent gates by Al-doped ZnO

    Institute of Scientific and Technical Information of China (English)

    Wang Chong; He Yun-Long; Zheng Xue-Feng; Ma Xiao-Hua; Zhang Jin-Cheng; Hao Yue

    2013-01-01

    AlGaN/GaN high-electron-mobility transistors (HEMTs) with Al-doped ZnO (AZO) transparent gate electrodes are fabricated,and Ni/Au/Ni-gated HEMTs are produced in comparison.The AZO-gated HEMTs show good DC characteristics and Schottky rectifying characteristics,and the gate electrodes achieve excellent transparencies.Compared with Ni/Au/Ni-gated HEMTs,AZO-gated HEMTs show a low saturation current,high threshold voltage,high Schottky barrier height,and low gate reverse leakage current.Due to the higher gate resistivity,AZO-gated HEMTs exhibit a current-gain cutoff frequency (fT) of 10 GHz and a power gain cutoff frequency (fmax) of 5 GHz,and lower maximum oscillation frequency than Ni/Au/Ni-gated HEMTs.Moreover,the C-V characteristics are measured and the gate interface characteristics of the AZO-gated devices are investigated by a C-V dual sweep.

  16. In-situ analyses on the reactive sputtering process to deposit Al-doped ZnO films using an Al-Zn alloy target

    Energy Technology Data Exchange (ETDEWEB)

    Tsukamoto, Naoki; Oka, Nobuto; Shigesato, Yuzo, E-mail: yuzo@chem.aoyama.ac.jp

    2012-03-01

    The kinetic energies of generated ions were investigated during the reactive sputtering process to deposit Al-doped ZnO (AZO) films using an Al-Zn alloy target. The sputtering system was equipped with specially designed double feedback system to stabilise the reactive sputtering processes and analysis was performed with a quadrupole mass spectrometer combined with an energy analyser. Negative ions O{sup -}, O{sub 2}{sup -}, AlO{sup -} and AlO{sub 2}{sup -} with high kinetic energies corresponding to cathode voltage are generated at the partially oxidised target surface, after which some of the ions undergo subsequent charge exchange and/or dissociation. Positive ions O{sup +}, Ar{sup +}, Zn{sup +} and Al{sup +} with lower kinetic energies (around 10 eV) are generated by charge exchange of sputtered neutral O, Ar, Zn and Al atoms, respectively. As the target surface oxidises, cathode voltage decrease, the flux of high-energy negative ions increases and the electrical properties of the AZO degrade by ion bombardment as well as the AZO films that are deposited by conventional magnetron sputtering using an AZO target.

  17. Band alignment at the interface between Ni-doped Cr2O3 and Al-doped ZnO: implications for transparent p-n junctions

    Science.gov (United States)

    Arca, Elisabetta; McInerney, Michael A.; Shvets, Igor V.

    2016-06-01

    The realization of transparent electronic and optoelectronic devices requires the use of transparent p-n junctions. In this context, understanding the band alignment at the interface between the p- and n-components represents a fundamental step towards the realization of high performance devices. In this work, the band alignment at the interface between Al-doped ZnO (AZO) and Ni-doped Cr2O3 has been analysed. The formation and evolution of the core levels as the interface progressively forms have been followed by means of x-ray Photoelectron Spectroscopy, x-ray diffraction and x-ray reflectivity. A type two (staggered) band alignment was identified, with the valence band offset and conduction band offset found to be 2.6 eV and 2.5 eV, respectively. The electrical behaviour will be discussed in terms of the position of the bands, the presence of band bending and the expected built-in potential and how these can be engineered in order to achieve the maximum performance for this hetero-structure.

  18. Compensation in Al-doped ZnO by Al-related acceptor complexes: synchrotron x-ray absorption spectroscopy and theory.

    Science.gov (United States)

    T-Thienprasert, J; Rujirawat, S; Klysubun, W; Duenow, J N; Coutts, T J; Zhang, S B; Look, D C; Limpijumnong, S

    2013-02-01

    The synchrotron x-ray absorption near edge structures (XANES) technique was used in conjunction with first-principles calculations to characterize Al-doped ZnO films. Standard characterizations revealed that the amount of carrier concentration and mobility depend on the growth conditions, i.e. H(2) (or O(2))/Ar gas ratio and Al concentration. First-principles calculations showed that Al energetically prefers to substitute on the Zn site, forming a donor Al(Zn), over being an interstitial (Al(i)). The measured Al K-edge XANES spectra are in good agreement with the simulated spectra of Al(Zn), indicating that the majority of Al atoms are substituting for Zn. The reduction in carrier concentration or mobility in some samples can be attributed to the Al(Zn)-V(Zn) and 2Al(Zn)-V(Zn) complex formations that have similar XANES features. In addition, XANES of some samples showed additional features that are the indication of some α-Al(2)O(3) or nAl(Zn)-O(i) formation, explaining their poorer conductivity.

  19. Coupling of Surface Plasmon Polariton in Al-Doped ZnO with Fabry-Pérot Resonance for Total Light Absorption

    Directory of Open Access Journals (Sweden)

    David George

    2017-04-01

    Full Text Available Al-doped ZnO (AZO can be used as an electrically tunable plasmonic material in the near infrared range. This paper presents finite-difference time-domain (FDTD simulations on total light absorption (TLA resulting from the coupling of a surface plasmon polariton (SPP with Fabry-Pérot (F-P resonance in a three-layer structure consisting of an AZO square lattice hole array, a spacer, and a layer of silver. Firstly, we identified that the surface plasmon polariton (SPP that will couple to the F-P resonance because of an SPP standing wave in the (1,0 direction of the square lattice. Two types of coupling between SPP and F-P resonance are observed in the simulations. In order to achieve TLA, an increase in the refractive index of the spacer material leads to a decrease in the thickness of the spacer. Additionally, it is shown that the replacement of silver by other, more cost-effective metals has no significance influence on the TLA condition. It is observed in the simulations that post-fabrication tunability of the TLA wavelength is possible via the electrical tunability of the AZO. Finally, electric field intensity distributions at specific wavelengths are computed to further prove the coupling of SPP with F-P resonance. This work will contribute to the design principle for future device fabrication for TLA applications.

  20. Significant improvement in performances of LiNi{sub 0.5}Mn{sub 1.5}O{sub 4} through surface modification with high ordered Al-doped ZnO electro-conductive layer

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Hongdan; Xia, Bingbo [College of Physics, Optoelectronics and Energy & Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, Suzhou 215006 (China); Key Laboratory of Lithium Ion Battery Materials of Jiangsu Province, Institute of Chemical Power Sources, Soochow University, Suzhou 215006 (China); Liu, Weiwei [Changzhou Institute of Energy Storage Materials & Devices, Changzhou 213000 (China); Fang, Guoqing; Wu, Jingjing; Wang, Haibo; Zhang, Ruixue [College of Physics, Optoelectronics and Energy & Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, Suzhou 215006 (China); Key Laboratory of Lithium Ion Battery Materials of Jiangsu Province, Institute of Chemical Power Sources, Soochow University, Suzhou 215006 (China); Kaneko, Shingo [Key Laboratory of Lithium Ion Battery Materials of Jiangsu Province, Institute of Chemical Power Sources, Soochow University, Suzhou 215006 (China); Zheng, Junwei [College of Physics, Optoelectronics and Energy & Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, Suzhou 215006 (China); Key Laboratory of Lithium Ion Battery Materials of Jiangsu Province, Institute of Chemical Power Sources, Soochow University, Suzhou 215006 (China); Wang, Hongyu [Changzhou Institute of Energy Storage Materials & Devices, Changzhou 213000 (China); Li, Decheng, E-mail: lidecheng@suda.edu.cn [College of Physics, Optoelectronics and Energy & Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, Suzhou 215006 (China); Key Laboratory of Lithium Ion Battery Materials of Jiangsu Province, Institute of Chemical Power Sources, Soochow University, Suzhou 215006 (China)

    2015-03-15

    Graphical abstract: Al-doped ZnO (AZO)-coated LiNi{sub 0.5}Mn{sub 1.5}O{sub 4} (LNMO) was prepared by sol–gel method. AZO-coated LNMO electrode shows excellent rate capability and a remarkable improvement in the cyclic performance at a high rate at elevated temperature. - Highlights: • Al-doped ZnO (AZO)-coated LiNi{sub 0.5}Mn{sub 1.5}O{sub 4} (LNMO) was prepared by a traditional sol–gel method. • Al-doped ZnO (AZO) layer grown on the surface of LNMO is high ordered. • At a high rate of 10 C, the discharge capacity of the AZO-coated LNMO electrode can reach 114 mAh g{sup −1}. • Al-doped ZnO (AZO) modification improved cyclic performance of LNMO at high temperatures. - Abstract: Al-doped ZnO (AZO)-coated LiNi{sub 0.5}Mn{sub 1.5}O{sub 4} (LNMO) was prepared by sol–gel method. Transmission electron microscopy (TEM) analysis indicates that AZO layer grown on the surface of LNMO is high ordered. The results of electrochemical performance measurements reveal that the AZO-coated LNMO electrode displays the best rate capability compared with the bare LNMO and ZnO-coated LNMO, even at a high rate of 10 C. The discharge capacity of the AZO-coated LNMO electrode can still reach 114.3 mAh g{sup −1}, about 89% of its discharge capacity at 0.1 C. Moreover, AZO-coated LNMO electrode shows a remarkable improvement in the cyclic performance at a high rate at elevated temperature due to the protective effect of AZO coating layer. The electrode delivers a capacity of 120.3 mAh g{sup −1} with the capacity retention of 95% at 5 C in 50 cycles at 50 °C. The analysis of electrochemical impedance spectra (EIS) indicates that AZO-coated LNMO possesses the lowest charge transfer resistance compared to the bare LNMO and ZnO-coated LNMO, which may be responsible for improved rate capability.

  1. High work function of Al-doped zinc-oxide thin films as transparent conductive anodes in organic light-emitting devices

    Science.gov (United States)

    Kim, T. W.; Choo, D. C.; No, Y. S.; Choi, W. K.; Choi, E. H.

    2006-12-01

    Deposition of Al-doped ZnO (AZO) films with various film thicknesses on glass substrates was performed to investigate the feasibility of using AZO films as anode electrodes in organic light-emitting devices (OLEDs). The electrical resistivity of the AZO films with a 180-nm thickness was 4.085 × 10 -2 Ω cm, and the average optical transmittance in the visible range was 80.2%. The surface work function for the AZO films, determined from the secondary electron emission coefficients obtained with a focused ion beam, was as high as 4.62 eV. These results indicate that AZO films grown on glass substrates hold promise for potential applications as anode electrodes in high-efficiency OLEDs.

  2. Effect of Al Doping on ZnO Nanocrystals Synthesized by Methanol Alcoholysis Method%Al掺杂对甲醇醇解法合成ZnO纳米粉体的影响

    Institute of Scientific and Technical Information of China (English)

    陈义川; 胡跃辉; 张效华; 杨丰; 陈新华; 陈俊

    2011-01-01

    采用醇解法,在130℃的甲醇溶液中分别合成纯的和Al掺杂纳米氧化锌(ZnO)晶体.使用X射线衍射仪,透射电子显微镜,Fourier红外光谱和偏振稳态荧光光谱对其晶体结构和光学性能进行了表征.结果表明:在甲醇溶液中,在较低的温度(130℃)下,成功制备出纳米ZnO晶体.Fourier红外吸收光谱表明醇解法合成的ZnO纳米晶体含有较少的有机物杂质.荧光光谱结果可以看出,纯ZnO和Al掺杂的ZnO纳米晶体在可见光范围(400nm~700nm)内有一个高的蓝光发光带(峰位为440nm)和一个绿光发光带(纯的和Al掺杂的峰位分别为520nm和530nm).通过对比发现掺杂Al可以有效的改变ZnO纳米粉体的可见光发光特性.%Undoped ZnO and Al doped ZnO nanocrystals were synthesized by the methanol alcoholysis method at 130℃. Structure, morphology and optical properties of ZnO nanocrystals were characterized using X-ray diffraction, transmission electron microscopy (TEM), Fourier transform infrared (FTIR) and photoluminescence (PL) spectra. The results show that ZnO nanocrystals can be obtained in methanol solution at low temperature (130℃)). FTIR spectra show that ZnO nanocrystals synthesized by the methanol alcoholysis include a little organic impurity. PL spectra reveal that pure ZnO and Al doped ZnO nanocrystals have a blue band emission at 440 nm and a green band emission at 520 nm and 530 nm, respectively. Compared with the pure ZnO nanocrystals, the Al doping improves the luminescent properties.

  3. Ferroelectric properties of (Pb,La)(Zr,Ti)O3 capacitors employing Al-doped ZnO top electrodes prepared by pulsed laser deposition under different oxygen pressures

    Science.gov (United States)

    Takada, Yoko; Okamoto, Naoki; Saito, Takeyasu; Kondo, Kazuo; Yoshimura, Takeshi; Fujimura, Norifumi; Higuchi, Koji; Kitajima, Akira

    2016-06-01

    Al-doped ZnO (AZO) top electrodes were deposited under oxygen pressures from 0.02 to 20 Pa using pulsed laser deposition (PLD) to fabricate ferroelectric (Pb,La)(Zr,Ti)O3 capacitors. The oxygen pressure during PLD affected the surface morphology of the AZO top electrodes as well as the ferroelectric properties. In particular, the surface morphologies were dramatically altered by increasing oxygen pressure. We obtained desirable ferroelectric properties with the highest maximum polarization and lowest coercive voltage at around 2.0 Pa. The saturation characteristics, hydrogen degradation resistance, and fatigue resistance were almost unrelated to the oxygen pressure during PLD.

  4. Effect of Al and Mg Doping on Optical Properties of ZnO Thin Films Prepared by Spin Coating

    Directory of Open Access Journals (Sweden)

    G. T Yusuf

    2014-08-01

    Full Text Available This paper investigated the influence of aluminum and magnesium doping on the optical and electrical properties of zinc oxide (ZnO thin films for solar cell application. Zinc acetate dehydrates was used as starting material. Aluminum chloride and tin chloride were added to each solution to serve as dopants. X-ray diffractions were analyzed by X-ray diffraction (XRD which revealed crystalline and hexagonal wurtzite structure. All the films showed more than 80% transparency in the visible region. The optical band gap of undoped ZnO thin film was found to be 3.12ev while that of Al-doped and Mg-doped ZnO film was estimated to be 3.16eV and 3.26eV respectively. The resistivity of the films measured were 2.51×10–4 Ω cm for Al-doped, 2.53×10–4 Ω cm for mg-doped and 2.61×10-4 Ω cm for undoped ZnO respectively. The quality of the films deposited in this work is a promising window layer component of a solar cell. The variation in the band gap observed in this work could be explained by Burstein–Moss effect which was fully explained in the discussion section of this work.

  5. Expanding Thermal Plasma Deposition of Al-Doped ZnO: On the Effect of the Plasma Chemistry on Film Growth Mechanisms

    NARCIS (Netherlands)

    Williams, B. L.; Ponomarev, M. V.; Verheijen, M. A.; Knoops, H. C. M.; Chandramohan, A.; Duval, L.; van de Sanden, M. C. M.; Creatore, M.

    2016-01-01

    This work presents a review of expanding thermal plasma – chemical vapour deposition (ETP-CVD) of Al-doped ZnOtransparent conducting oxides (TCOs), alongside new results providing insights into the role of the plasma chemistry on film microstructure. Standard growth conditions generate high

  6. Expanding Thermal Plasma Deposition of Al-Doped ZnO: On the Effect of the Plasma Chemistry on Film Growth Mechanisms

    NARCIS (Netherlands)

    Williams, B. L.; Ponomarev, M. V.; Verheijen, M. A.; Knoops, H. C. M.; Chandramohan, A.; Duval, L.; van de Sanden, M. C. M.; Creatore, M.

    2016-01-01

    This work presents a review of expanding thermal plasma – chemical vapour deposition (ETP-CVD) of Al-doped ZnOtransparent conducting oxides (TCOs), alongside new results providing insights into the role of the plasma chemistry on film microstructure. Standard growth conditions generate high resistiv

  7. Enhancement of photoinduced electrical properties of Al-doped ZnO/BiFeO3 layered thin films prepared by chemical solution deposition

    Science.gov (United States)

    Katayama, Takeshi; Sakamoto, Wataru; Yuitoo, Isamu; Takeuchi, Teruaki; Hayashi, Koichiro; Yogo, Toshinobu

    2015-10-01

    Polycrystalline BiFeO3 and Al-doped ZnO/BiFeO3 bilayered thin films were prepared on Pt/TiOx/SiO2/Si substrates by chemical solution deposition. Their photoinduced electrical properties under blue light irradiation were characterized. The rapid on/off response of the photocurrent to light in unpoled BiFeO3 (BFO) and Al-doped ZnO/BiFeO3 (AZO/BFO) thin films was demonstrated. The AZO/BFO layered film exhibited an approximately triple-digit larger photocurrent in comparison with a BFO single-layer film. This is attributable to the photoexcited carrier generation effect at the interface between AZO (n-type) and BFO (p-type) films. Furthermore, in the AZO/BFO layered structure, the direction of the internal bias electric field caused by the space charge distribution in the unpoled BFO film is the same as that of the built-in electric field by forming a p-n junction of AZO and BFO layers. Photovoltaic properties were also improved by fabricating such a layered film. On the other hand, when the placement of BFO to AZO was reversed, the photoelectric current decreased to approximately one-tenth of that of the BFO single-layer film. In the BFO/AZO film, the internal electric field at the p-n junction between BFO and AZO is considered to have an orientation opposite to the self-bias field formed in the BFO film.

  8. Microstructure and optical properties of nanocrystalline ZnO and ZnO:(Li or Al) thin films

    Energy Technology Data Exchange (ETDEWEB)

    Oral, A. Yavuz [Department of Materials Science and Engineering, Gebze Institute of Technology, Gebze 41400 (Turkey)]. E-mail: aoral@gyte.edu.tr; Bahsi, Z. Banu [Department of Materials Science and Engineering, Gebze Institute of Technology, Gebze 41400 (Turkey); Aslan, M. Hasan [Department of Physics, Gebze Institute of Technology, Gebze 41400 (Turkey)

    2007-03-15

    Zinc oxide thin films (ZnO, ZnO:Li, ZnO:Al) were deposited on glass substrates by a sol-gel technique. Zinc acetate, lithium acetate, and aluminum chloride were used as metal ion sources in the precursor solutions. XRD analysis revealed that Li doped and undoped ZnO films formed single phase zincite structure in contrast to Al:ZnO films which did not fully crystallize at the annealing temperature of 550 deg. C. Crystallized films had a grain size under 50 nm and showed c-axis grain orientation. All films had a very smooth surface with RMS surface roughness values between 0.23 and 0.35 nm. Surface roughness and optical band tail values increased by Al doping. Compared to undoped ZnO films, Li doping slightly increased the optical band gap of the films.

  9. Double-beam pulsed laser deposition for the growth of Al-incorporated ZnO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Moreno, L. [Centro de Ciencias Aplicadas y Desarrollo Tecnológico, Universidad Nacional Autónoma de México, Circuito Exterior S/N, Ciudad Universitaria, AP 70-186, C.P. 04510 México D.F., México (Mexico); Sánchez-Aké, C., E-mail: citlali.sanchez@ccadet.unam.mx [Centro de Ciencias Aplicadas y Desarrollo Tecnológico, Universidad Nacional Autónoma de México, Circuito Exterior S/N, Ciudad Universitaria, AP 70-186, C.P. 04510 México D.F., México (Mexico); Bizarro, M. [Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, Apartado Postal 70-186, C.P. 04510 México D.F., México (Mexico)

    2014-05-01

    Pulsed laser deposition in a delayed-double beam configuration is used to incorporate in situ Al in ZnO thin films. In this configuration, two synchronized pulsed-laser beams are employed to ablate independently a ZnO and an Al target. We investigated the effects of relative time delay of plasma plumes on the composition of the films with the aim of evaluating the performance of this technique to produce doped materials. Relative delay between plumes was found to control the incorporation of Al in the film in the range from 14% to 30%. However, to produce low impurity concentration of Al-doped ZnO (with Al incorporation less than 2%) the fluence used to produce the plasmas has more influence over the film composition than the relative plume delay. The minimum incorporation of Al corresponded to a relative delay of 0 μs, due to the interaction between plumes during their expansion.

  10. Al掺杂ZnO纳米棒的性能研究及其在太阳能电池中的应用%Properties of Al-doped ZnO nanorods and the application in organic photovoltaic devices

    Institute of Scientific and Technical Information of China (English)

    丁国静; 秦文静; 杨利营; 黄康; 印寿根

    2012-01-01

    We fabricated the ZnO nanorods with different Al3+-doped concentrations of 0 %, 0.5 %, 1.0 % and 1.5 %, respectively. The morphology and the crystalline of/M-doped ZnO nanorods are investigated by using scanning electron microscope (SEM) and X-ray diffraction (XRD). The optical and electrical properties are researched by ultraviolet-visible (UV-VIS) absorption spectroscopy,time-resolved photo- luminescence (TRPL) spectroscopy and sheet resistance. The analysis indicates that the ZnO nanorods are orderly arrayed and have good crystallinity. As the Al3+ doped concentration increasing,the conductivity of ZnO is improved and the electron transfer between donor and acceptor becomes faster. Finally, Al-doped ZnO nanorods are incorporated in the organic photovoltaic devices as both cathode and electron conductive layer. The optimized device (at lower doping of 0.5%) shows 30% higher Jsc and 50% higher photoelectric conversion efficiency (PCE) compared with the device without Al doping.%通过水热法制备了不同质量分数(0%,0.5%,1.0%和1.5%)的Al3+掺杂ZnO纳米棒,扫描电镜(SEM)、X射线衍射(XRD)、紫外-可见(UV—vis)吸收光谱等测试结果表明,通过这种方法得到了较为规整的ZnO纳米阵列,结晶良好、具有明显的C轴生长取向;掺杂浓度的增加对产物的形貌和晶体结构产生了明显的影响。通过瞬态光谱和面电阻测试发现,Al3+掺杂提高了ZnO传导电子的能力。将Al3+掺杂的ZnO纳米棒同时作为电极与电子传输层,应用于有机太阳能电池器件中,在低浓度(0.5at.%)掺杂时得到最佳的器件性能,相比于未掺杂的ZnO纳米棒,短路电流提高了30%,光电转化效率提高了50%。

  11. Induced growth of high quality ZnO thin films by crystallized amorphous ZnO

    Institute of Scientific and Technical Information of China (English)

    Wang Zhi-Jun; Song Li-Jun; Li Shou-Chun; Lu You-Ming; Tian Yun-Xia; Liu Jia-Yi; Wang Lian-Yuan

    2006-01-01

    This paper reports the induced growth of high quality ZnO thin film by crystallized amorphous ZnO. Firstly amorphous ZnO was prepared by solid-state pyrolytic reaction, then by taking crystallized amorphous ZnO as seeds (buffer layer), ZnO thin films have been grown in diethyene glycol solution of zinc acetate at 80℃. X-ray Diffraction curve indicates that the films were preferentially oriented [001] out-of-plane direction of the ZnO. Atomic force microscopy and scanning electron microscopy were used to evaluate the surface morphology of the ZnO thin film. Photoluminescence spectrum exhibits a strong ultraviolet emission while the visible emission is very weak. The results indicate that high quality ZnO thin film was obtained.

  12. Enhanced light extraction of GaN-based light-emitting diodes with periodic textured SiO2 on Al-doped ZnO transparent conductive layer

    Science.gov (United States)

    Yu, Zhao; Bingfeng, Fan; Yiting, Chen; Yi, Zhuo; Zhoujun, Pang; Zhen, Liu; Gang, Wang

    2016-07-01

    We report an effective enhancement in light extraction of GaN-based light-emitting diodes (LEDs) with an Al-doped ZnO (AZO) transparent conductive layer by incorporating a top regular textured SiO2 layer. The 2 inch transparent through-pore anodic aluminum oxide (AAO) membrane was fabricated and used as the etching mask. The periodic pore with a pitch of about 410 nm was successfully transferred to the surface of the SiO2 layer without any etching damages to the AZO layer and the electrodes. The light output power was enhanced by 19% at 20 mA and 56% at 100 mA compared to that of the planar LEDs without a patterned surface. This approach offers a technique to fabricate a low-cost and large-area regular pattern on the LED chip for achieving enhanced light extraction without an obvious increase of the forward voltage. ).

  13. Influence of transparent conductive oxides on passivation of a-Si:H/c-Si heterojunctions as studied by atomic layer deposited Al-doped ZnO

    Science.gov (United States)

    Macco, B.; Deligiannis, D.; Smit, S.; van Swaaij, R. A. C. M. M.; Zeman, M.; Kessels, W. M. M.

    2014-12-01

    In silicon heterojunction solar cells, the main opportunities for efficiency gain lie in improvements of the front-contact layers. Therefore, the effect of transparent conductive oxides (TCOs) on the a-Si:H passivation performance has been investigated for Al-doped zinc oxide (ZnO:Al) layers made by atomic layer deposition (ALD). It is shown that the ALD process, as opposed to sputtering, does not impair the chemical passivation. However, the field-effect passivation is reduced by the ZnO:Al. The resulting decrease in low injection-level lifetime can be tuned by changing the ZnO:Al doping level (carrier density = 7 × 1019-7 × 1020 cm-3), which is explained by a change in the TCO workfunction. Additionally, it is shown that a ˜10-15 nm ALD ZnO:Al layer is sufficient to mitigate damage to the a-Si:H by subsequent sputtering, which is correlated to ALD film closure at this thickness.

  14. Al and Fe co-doped transparent conducting ZnO thin film for mediator-less biosensing application

    Directory of Open Access Journals (Sweden)

    Shibu Saha

    2011-12-01

    Full Text Available Highly c-axis oriented Al and Fe co-doped ZnO (ZAF thin film is prepared by pulsed laser deposition. Fe introduces redox centre along with shallow donor level while Al doping enhances conductivity of ZnO, thus removing the requirement of both mediator and bottom conducting layer in bioelectrode. Model enzyme (glucose oxidase, was immobilized on surface of ZAF matrix. Cyclic voltammetry and photometric assay show that prepared bio-electrode is sensitive to glucose concentration with enhanced response of 0.18 μAmM-1cm-2 and low Km ∼ 2.01 mM. The results illustrate that ZAF is an attractive matrix for realization of miniaturized mediator-less solid state biosensor.

  15. Influence of low sputtering pressure on structural, electrical and optical properties of Al-doped zinc oxide thin films

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Zengguang; Tang, Yang, E-mail: tangyang@nicenergy.com; Chen, Jingyun; Chen, Jie

    2016-08-15

    Aluminum-doped zinc oxide thin films were deposited without intentional heating by radio-frequency magnetron sputtering. The sputtering pressure varied from 0.02 Pa to 0.32 Pa while the deposition power was kept at 240 W for all depositions. The structural properties of as-deposited films were analyzed by X-ray diffraction and scanning electron microscopy, indicating that the deposited films have a strong preferred c-axis (002) orientation perpendicular to the substrate regardless of sputtering pressure. The minimum resistivity of 6.4×10{sup −4} Ω cm is obtained at 0.05 Pa, which is mainly influenced by the hall mobility, rather than carrier concentration. The highest transmittance could be ~80% on average in the visible range under various working pressures, and the largest bandgap achieved is about 3.82 eV. The ultraviolet emission peaks in photoluminescence spectra are centered at about 360 nm. A new mechanism is proposed to explain the dependence of the electrical and optical properties on structural evolution of deposited films.

  16. Evolution of Surface Morphology and Chemistry in ZnO Thin Films and Steel Surfaces studied by Synchrotron X-ray Spectroscopy and Imaging

    Science.gov (United States)

    Jiang, Hua

    Thin film and surface treatment play an important role in developing materials with unique properties. They have been widely used in energy generation and storage, optical devices, LEDS, electrical semiconductor devices, etc. The stability and functionality of them under operational environment are important, especially the surface morphology and chemical evolution at micro-scale. This information is critical to understand the behaviors of the materials under various environments for a wide range of applications. Synchrotron x-ray fluorescence (XRF) and x-ray absorption near edge structure (XANES) are suitable techniques on investigating surface morphology and chemical evolution. Here, we use both techniques to investigate chemical and morphological heterogeneity of zinc oxide thin films after environmental humidity exposure, as well as surface and chemical evolution of iron oxidation states during iron redox process for samples with/without surface anti-corrosion treatment. Zinc oxide (ZnO) thin films have been reported to suffer from degradation in electrical properties, leading to failure of electronics due to environmental factors, such as heat and humidity. While degradation appears to be linked to water and oxygen penetration in the ZnO film, a direct observation in ZnO film morphological evolution, in conjunction with structural and chemical changes is lacking. Here, we systematically investigated the chemical and morphological heterogeneity of ZnO thin films caused by steam treatment. X-ray fluorescence microscopy, absorption spectroscopy, grazing incident small angle and wide angle scattering, scanning electron microscopy (SEM), ultra-high-resolution SEM and optical microscopy were carried out to examine ZnO, Al-doped ZnO and Ga-doped ZnO thin films, on two different substrates - silicon wafer and PET film. The environmental aging introduced pin-holes in the un-doped ZnO thin film. More significant morphological features formed in the Al-doped ZnO thin

  17. Atomic layer deposition of high-quality Al{sub 2}O{sub 3} and Al-doped TiO{sub 2} thin films from hydrogen-free precursors

    Energy Technology Data Exchange (ETDEWEB)

    Aarik, Lauri, E-mail: lauri.aarik@ut.ee [University of Tartu, Institute of Physics, Riia 142, 51014 Tartu (Estonia); Arroval, Tõnis; Rammula, Raul; Mändar, Hugo [University of Tartu, Institute of Physics, Riia 142, 51014 Tartu (Estonia); Sammelselg, Väino [University of Tartu, Institute of Physics, Riia 142, 51014 Tartu (Estonia); University of Tartu, Institute of Chemistry, Ravila 14A, 50411 Tartu (Estonia); Hudec, Boris; Hušeková, Kristína; Fröhlich, Karol [Institute of Electrical Engineering, Slovak Academy of Sciences, Dúbravská cesta 9, 841 04 Bratislava (Slovakia); Aarik, Jaan [University of Tartu, Institute of Physics, Riia 142, 51014 Tartu (Estonia)

    2014-08-28

    Possibilities for atomic layer deposition of Al{sub 2}O{sub 3} films from chloride and ozone were studied in order to avoid application of precursors that could leave hydrogen impurities in the films. Growth of Al{sub 2}O{sub 3} was obtained at substrate temperatures of 300–450 °C. At these temperatures, the growth rate was close to the values reported for corresponding H{sub 2}O-based processes. Studies of thin-film composition revealed that reactivity of O{sub 3} was sufficient to ensure deposition of films with chlorine concentration below 0.05 at.% at 350–450 °C. Application of the AlCl{sub 3}–O{sub 3} atomic layer deposition process for in situ Al-doping of TiO{sub 2} thin films demonstrated that the amount of Al incorporated into the films during a single deposition cycle depended on the doping level. A reason for this effect was the influence of Al-doping on the phase composition of the film material. Al-doping of the TiO{sub 2} films significantly reduced the surface roughness allowing deposition of high-density films with very flat surfaces. In capacitor structures with capacitance equivalent oxide thicknesses below 0.4 nm, the Al-doped TiO{sub 2} films deposited from TiCl{sub 4}, AlCl{sub 3} and O{sub 3} demonstrated markedly lower leakage current densities than the films with similar capacitance densities grown from TiCl{sub 4}, Al(CH{sub 3}){sub 3} and H{sub 2}O and from TiCl{sub 4}, Al(CH{sub 3}){sub 3} and O{sub 3} did. - Highlights: • Atomic layer deposition of thin films from AlCl{sub 3} and O{sub 3} was investigated. • Growth of Al{sub 2}O{sub 3} was obtained at temperatures 300–450 °C. • Growth rates up to 0.069 nm per cycle were observed. • Deposition of Al-doped TiO{sub 2} films from TiCl{sub 4}, AlCl{sub 3} and O{sub 3} was studied. • Films with superior dielectric properties were grown in the hydrogen-free process.

  18. Low operation voltage of GaN-based LEDs with Al-doped ZnO upper contact directly on p-type GaN without insert layer

    Science.gov (United States)

    Chen, P. H.; Chen, Yu An; Chang, L. C.; Lai, W. C.; Kuo, Cheng Huang

    2015-07-01

    Al-doped ZnO (AZO) film was evaporated on double-side polished sapphire, p-GaN layers, n+-InGaN-GaN short-period superlattice (SPS) structures, and GaN-based light-emitting diodes (LEDs) by e-beam. The AZO film on the p-GaN layer after thermal annealing exhibited an extremely high transparency (98% at 450 nm) and a small specific contact resistance of 2.19 × 10-2 Ω cm2, which was almost the same as that of as-deposited AZO on n+-SPS structure. With 20 mA injection current, the forward voltages were 3.30 and 3.27 V, whereas the output powers were 4.32 and 4.07 mW for the LED with AZO on insert n+-SPS upper contact and the LED with AZO on p-GaN upper contact (without insert layer), respectively. The small specific contact resistance and low operation voltage of LED with AZO on p-GaN upper contact was achieved by rapid thermal annealing (RTA) process.

  19. Significant improvement in performances of LiNi0.5Mn1.5O4 through surface modification with high ordered Al-doped ZnO electro-conductive layer

    Science.gov (United States)

    Sun, Hongdan; Xia, Bingbo; Liu, Weiwei; Fang, Guoqing; Wu, Jingjing; Wang, Haibo; Zhang, Ruixue; Kaneko, Shingo; Zheng, Junwei; Wang, Hongyu; Li, Decheng

    2015-03-01

    Al-doped ZnO (AZO)-coated LiNi0.5Mn1.5O4 (LNMO) was prepared by sol-gel method. Transmission electron microscopy (TEM) analysis indicates that AZO layer grown on the surface of LNMO is high ordered. The results of electrochemical performance measurements reveal that the AZO-coated LNMO electrode displays the best rate capability compared with the bare LNMO and ZnO-coated LNMO, even at a high rate of 10 C. The discharge capacity of the AZO-coated LNMO electrode can still reach 114.3 mAh g-1, about 89% of its discharge capacity at 0.1 C. Moreover, AZO-coated LNMO electrode shows a remarkable improvement in the cyclic performance at a high rate at elevated temperature due to the protective effect of AZO coating layer. The electrode delivers a capacity of 120.3 mAh g-1 with the capacity retention of 95% at 5 C in 50 cycles at 50 °C. The analysis of electrochemical impedance spectra (EIS) indicates that AZO-coated LNMO possesses the lowest charge transfer resistance compared to the bare LNMO and ZnO-coated LNMO, which may be responsible for improved rate capability.

  20. Microstructure and blueshift in optical band gap of nanocrystalline Al{sub x}Zn{sub 1−x}O thin films

    Energy Technology Data Exchange (ETDEWEB)

    Majeed Khan, M.A., E-mail: majeed_phys@rediffmail.com [King Abdullah Institute for Nanotechnology, King Saud University, Riyadh 11451 (Saudi Arabia); Kumar, Sushil [Materials ScienceLaboratory, Department of Physics, Chaudhary Devi Lal University, Sirsa 125055 (India); Naziruddin Khan, M.; Ahamed, Maqusood [King Abdullah Institute for Nanotechnology, King Saud University, Riyadh 11451 (Saudi Arabia); Al Dwayyan, A.S. [King Abdullah Institute for Nanotechnology, King Saud University, Riyadh 11451 (Saudi Arabia); Physics and Astronomy Department, College of Science, King Saud University, P.O. Box 2455, Riyadh 11451 (Saudi Arabia)

    2014-11-15

    In this paper, we report the structural and optical properties of Al doped ZnO (AZO) thin films grown on glass substrates using the sol–gel process. To understand the effect of Al doping on the structural and optical response of ZnO nanoparticles thin films, the prepared samples have been characterized using X-ray diffraction (XRD), energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), photoluminescence (PL), UV–vis absorption and Raman spectroscopy. X-ray diffraction results show that Al doped ZnO nanoparticles have hexagonal phase similar to ZnO nanoparticles. TEM images as well as XRD data exhibit the estimated size of nanoparticles to be in the range 35–45 nm. The optical band gap has been determined from optical absorption spectra. The band gap varied from 3.27 eV for undoped ZnO film to 3.87 eV for AZO film having 3 atwt% Al. The blue shift in energy band gap mainly related to carrier concentration induced by Al-donor doping, and to the degree of crystalline order. Photoluminescence study further confirms the blue shift in UV emission when Al doping concentration is increased, as a consequence of extension in band gap. - Highlights: • Undoped and Al doped ZnO nanoparticles has been synthesized by the sol–gel method. • Undoped and Al doped ZnO films have a (0 0 2) peak, indicating a hexagonal wurtzite structure. • The stacking faults induced by Al-doped provide another path for electron transfer. • Influence of Al doping on the physical properties of ZnO nanoparticles was investigated. • The quality and crystallinity of Al-doped ZnO films were investigated by varying the Al compositions.

  1. Atomic layer deposition of Al-doped ZnO films using ozone as the oxygen source: A comparison of two methods to deliver aluminum

    Energy Technology Data Exchange (ETDEWEB)

    Yuan Hai; Luo Bing; Yu Dan; Cheng, An-jen; Campbell, Stephen A.; Gladfelter, Wayne L. [Department of Electrical and Computer Engineering and Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455 and School of Materials Science and Engineering, Northwestern Polytechnical University, Xi' an, Shaan' xi 710025 (China); Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455 (United States); Department of Electrical and Computer Engineering, University of Minnesota, Minneapolis, Minnesota 55455 (United States); Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455 (United States)

    2012-01-15

    Aluminum-doped ZnO films were prepared by atomic layer deposition at 250 deg. C using diethylzinc (DEZ), trimethylaluminum (TMA), and ozone as the precursors. Two deposition methods were compared to assess their impact on the composition, structural, electrical, and optical properties as a function of Al concentration. The first method controlled the Al concentration by changing the relative number of Al to Zn deposition cycles; a process reported in the literature where water was used as the oxygen source. The second method involved coinjection of the DEZ and TMA during each cycle where the partial pressures of the precursors control the aluminum concentration. Depth profiles of the film composition using Auger electron spectroscopy confirmed a layered microstructure for the films prepared by the first method, whereas the second method led to a homogeneous distribution of the aluminum throughout the ZnO film. Beneath the surface layer the carbon concentrations for all of the films were below the detection limit. Comparison of their electrical and optical properties established that films deposited by coinjection of the precursors were superior.

  2. Epsilon-Near-Zero Al-Doped ZnO for Ultrafast Switching at Telecom Wavelengths: Outpacing the Traditional Amplitude-Bandwidth Trade-Off

    CERN Document Server

    Kinsey, N; Kim, J; Ferrera, M; Shalaev, V M; Boltasseva, A

    2015-01-01

    Transparent conducting oxides have recently gained great attention as CMOS-compatible materials for applications in nanophotonics due to their low optical loss, metal-like behavior, versatile/tailorable optical properties, and established fabrication procedures. In particular, aluminum doped zinc oxide (AZO) is very attractive because its dielectric permittivity can be engineered over a broad range in the near infrared and infrared. However, despite all these beneficial features, the slow (> 100 ps) electron-hole recombination time typical of these compounds still represents a fundamental limitation impeding ultrafast optical modulation. Here we report the first epsilon-near-zero AZO thin films which simultaneously exhibit ultra-fast carrier dynamics (excitation and recombination time below 1 ps) and an outstanding reflectance modulation up to 40% for very low pump fluence levels (< 4 mJ/cm2) at the telecom wavelength of 1.3 {\\mu}m. The unique properties of the demonstrated AZO thin films are the result of...

  3. Chemical shift and surface characteristics of Al-doped ZnO thin film on SiOC dielectrics.

    Science.gov (United States)

    Oh, Teresa; Lee, Sang Yeol

    2013-10-01

    Aluminum doped zinc oxide (AZO) films were fabricated on SiOC/p-Si wafer and SiOC film was prepared on a p-type Si substrate with the SiC target at oxygen ambient with the gas flow rate of 5-30 sccm by a RF magnetron sputter. C-V curve of SiOC/Si wafer was measured to observe the relationship between the polarity of SiOC dielectrics and the change of capacitance depending on oxygen gas flow rate. The SiOC film could be controlled to be polar or nonpolar, and their surface energy was changed depending on the polarity. Smooth surface is essential to improve the TFT performance. AZO-TFTs used smooth SiOC film with low polarity as a gate insulator was observed to show low leakage current (IL) and low subthreshold voltage swing. It is proposed that SiOC film with high degree amorphous structure as a gate insulator between AZO and Si wafer could solve problems of the mismatched interfaces, which was originated from the electron scattering due to the grain boundary.

  4. High-performance InGaN/GaN MQW LEDs with Al-doped ZnO transparent conductive layers grown by MOCVD using H2O as an oxidizer

    Science.gov (United States)

    Lin, Jia-Yong; Pei, Yan-Li; Zhuo, Yi; Chen, Zi-Min; Hu, Rui-Qin; Cai, Guang-Shuo; Wang, Gang

    2016-11-01

    In this study, the high performance of InGaN/GaN multiple quantum well light-emitting diodes (LEDs) with Al-doped ZnO (AZO) transparent conductive layers (TCLs) has been demonstrated. The AZO-TCLs were fabricated on the n+-InGaN contact layer by metal organic chemical vapor deposition (MOCVD) using H2O as an oxidizer at temperatures as low as 400 °C without any post-deposition annealing. It shows a high transparency (98%), low resistivity (510-4 Ω·cm), and an epitaxial-like excellent interface on p-GaN with an n+-InGaN contact layer. A forward voltage of 2.82 V @ 20 mA was obtained. Most importantly, the power efficiencies can be markedly improved by 53.8%@20 mA current injection and 39.6%@350 mA current injection compared with conventional LEDs with indium tin oxide TCL (LED-III), and by 28.8%@20 mA current injection and 4.92%@350 mA current injection compared with LEDs with AZO-TCL prepared by MOCVD using O2 as an oxidizer (LED-II), respectively. The results indicate that the AZO-TCL grown by MOCVD using H2O as an oxidizer is a promising TCL for a low-cost and high-efficiency GaN-based LED application. Project supported by the National Natural Science Foundation of China (Grant Nos. 61204091, 61404177, 51402366, and U1201254) and the Science and Technology Planning Project of Guangdong Province, China (Grant No. 2015B010132006).

  5. Transparent Conducting Oxides for Infrared Plasmonic Waveguides: ZnO (Preprint)

    Science.gov (United States)

    2014-01-15

    AFRL-RY-WP-TP-2014-0009 TRANSPARENT CONDUCTING OXIDES FOR INFRARED PLASMONIC WAVEGUIDES: ZnO (PREPRINT) Monica Allen, Jeffery Allen...CONDUCTING OXIDES FOR INFRARED PLASMONIC WAVEGUIDES: ZnO (PREPRINT) 5a. CONTRACT NUMBER In-house 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER N...for plasmonic waveguiding applications with an emphasis on highly conducting ZnO . In addition, the paper contains analysis of a set of thin Al-doped

  6. Highly transparent and conductive Sn/F and Al co-doped ZnO thin films prepared by sol–gel method

    Energy Technology Data Exchange (ETDEWEB)

    Pan, Zhanchang, E-mail: panzhanchang@163.com [School of Chemical Engineering and Light Industry, Guangdong University of Technology, Guangzhou, Guangdong 510006 (China); Luo, Junming [School of Chemical Engineering and Light Industry, Guangdong University of Technology, Guangzhou, Guangdong 510006 (China); Tian, Xinlong, E-mail: tianxinlong2010@163.com [School of Chemical Engineering and Light Industry, Guangdong University of Technology, Guangzhou, Guangdong 510006 (China); Wu, Shoukun; Chen, Chun; Deng, Jianfeng [Huizhou King Brother Electronic Technology Co., Ltd, Huizhou 516083 (China); Xiao, Chumin [School of Chemical Engineering and Light Industry, Guangdong University of Technology, Guangzhou, Guangdong 510006 (China); Hu, Guanghui, E-mail: qhxy123@126.com [School of Chemical Engineering and Light Industry, Guangdong University of Technology, Guangzhou, Guangdong 510006 (China); Wei, Zhigang [School of Chemical Engineering and Light Industry, Guangdong University of Technology, Guangzhou, Guangdong 510006 (China)

    2014-01-15

    Highlights: • F/Sn and Al co-doped ZnO thin films were synthesized by sol–gel method. • The co-doped nanocrystals exhibit good crystal quality. • The origin of the photoluminescence emissions was discussed. • The films showed high transmittance and low resistivity. -- Abstract: Al doped ZnO, Al–Sn co-doped ZnO and Al–F co-doped ZnO nanocrystals were successfully synthesized onto glass substrates by the sol–gel method. The structure and morphology of the films are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and high resolution transmission electron microscopy (HRTEM). The results indicated that all the films were polycrystalline with a hexagonal wurtzite structure and exhibited a c-axis preferred orientation. The electrical and optical properties were also investigated by 4-point probe device and Uv–vis spectroscopy, room temperature photoluminescence (PL) and Raman spectrum (Raman), respectively. The PL and Raman results suggested that the co-doped films with a very low defect concentration and exhibit a better crystallinity than AZO thin films. The XPS study confirmed the incorporation of Al, Sn and F ions in the ZnO lattice.

  7. ZnO thin films prepared by pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Tsoutsouva, M.G. [Laboratory of Physical Metallurgy, National Technical University of Athens, Zografos, 15780 Athens (Greece); Panagopoulos, C.N., E-mail: chpanag@metal.ntua.gr [Laboratory of Physical Metallurgy, National Technical University of Athens, Zografos, 15780 Athens (Greece); Papadimitriou, D. [National Technical University of Athens, Department of Physics, GR-15780 Athens (Greece); Fasaki, I.; Kompitsas, M. [Theor. and Phys./Chem. Institute, National Hellenic Research Foundation, 48 Vas. Konstantinou Ave., 11635 Athens (Greece)

    2011-04-15

    Zinc oxide (ZnO) thin films were deposited on soda lime glass substrates by pulsed laser deposition (PLD) in an oxygen-reactive atmosphere. The structural, optical, and electrical properties of the as-prepared thin films were studied in dependence of substrate temperature and oxygen pressure. High quality polycrystalline ZnO films with hexagonal wurtzite structure were deposited at substrate temperatures of 100 and 300 deg. C. The RMS roughness of the deposited oxide films was found to be in the range 2-9 nm and was only slightly dependent on substrate temperature and oxygen pressure. Electrical measurements indicated a decrease of film resistivity with the increase of substrate temperature and the decrease of oxygen pressure. The ZnO films exhibited high transmittance of 90% and their energy band gap and thickness were in the range 3.26-3.30 eV and 256-627 nm, respectively.

  8. ZnO Thin Film Electronics for More than Displays

    Science.gov (United States)

    Ramirez, Jose Israel

    Zinc oxide thin film transistors (TFTs) are investigated in this work for large-area electronic applications outside of display technology. A constant pressure, constant flow, showerhead, plasma-enhanced atomic layer deposition (PEALD) process has been developed to fabricate high mobility TFTs and circuits on rigid and flexible substrates at 200 °C. ZnO films and resulting devices prepared by PEALD and pulsed laser deposition (PLD) have been compared. Both PEALD and PLD ZnO films result in densely packed, polycrystalline ZnO thin films that were used to make high performance devices. PEALD ZnO TFTs deposited at 300 °C have a field-effect mobility of ˜ 40 cm2/V-s (and > 20 cm2/V-S deposited at 200 °C). PLD ZnO TFTs, annealed at 400 °C, have a field-effect mobility of > 60 cm2/V-s (and up to 100 cm2/V-s). Devices, prepared by either technique, show high gamma-ray radiation tolerance of up to 100 Mrad(SiO2) with only a small radiation-induced threshold voltage shift (VT ˜ -1.5 V). Electrical biasing during irradiation showed no enhanced radiation-induced effects. The study of the radiation effects as a function of material stack thicknesses revealed the majority of the radiation-induced charge collection happens at the semiconductor-passivation interface. A simple sheet-charge model at that interface can describe the radiation-induced charge in ZnO TFTs. By taking advantage of the substrate-agnostic process provided by PEALD, due to its low-temperature and excellent conformal coatings, ZnO electronics were monolithically integrated with thin-film complex oxides. Application-based examples where ZnO electronics provide added functionality to complex oxide-based devices are presented. In particular, the integration of arrayed lead zirconate titanate (Pb(Zr, Ti)O3 or PZT) thin films with ZnO electronics for microelectromechanical systems (MEMs) and deformable mirrors is demonstrated. ZnO switches can provide voltage to PZT capacitors with fast charging and slow

  9. Thin films of conductive ZnO patterned by micromolding resulting in nearly isolated features

    NARCIS (Netherlands)

    Göbel, Ole F.; Blank, Dave H.A.; Elshof, ten Johan E.

    2010-01-01

    Patterned and continuous thin films of conductive Al-doped zinc oxide (ZnO:Al) were prepared on different substrates from a polymeric precursor solution. Their electric conductivity and light transmittance (for visible and UV light) was measured at room temperature. By means of a simple device, cond

  10. Compositional and physico-optical characterization of 0-5% Al-doped zinc oxide films prepared by chemical spray pyrolysis

    Energy Technology Data Exchange (ETDEWEB)

    Romero, R; Lopez-Ibanez, R; Ramos-Barrado, J R; Martin, F; Leinen, D [Laboratorio de Materiales y Superficie (Unidad Asociada al CSIC), Dpto. Fisica Aplicada I and Dpto. IngenierIa Quimica, Universidad de Malaga, E-29071 Malaga (Spain); Dalchiele, E A, E-mail: dietmar@uma.e [Instituto de Fisica, Facultad de IngenierIa, Universidad de la Republica, Herrera y Reissig 565, C.C. 30, 11000 Montevideo (Uruguay)

    2010-03-10

    Highly transparent polycrystalline Al-doped ZnO thin films were deposited in open atmosphere by chemical spray pyrolysis on fused silica and glass substrates at 623 K. The influence of Al doping, 0 to 5%, was studied. XPS results revealed a linear relationship between Al content in the precursor solutions and Al content in the films. XPS depth profiling showed that any carbon contamination is restricted to the uppermost surface of the films. Optical transmission measurements revealed an increasing number of dispersion centres as well as a band gap shift to higher values with increasing Al content in the films. At fixed Al concentration, the comparison of the absorption coefficient for increasing film thickness showed that the films are very homogeneous, not changing their materials properties such as absorption coefficient and band gap.

  11. Influence of process parameters on band gap of AI-doped ZnO film

    Institute of Scientific and Technical Information of China (English)

    Diqiu HUANG; Xiangbin ZENG; Yajuan ZHENG; Xiaojin WANG; Yanyan YANG

    2013-01-01

    This paper presents the influence of process parameters, such as argon (Ar) flow rate, sputtering power and substrate temperature on the band gap of Al-doped ZnO film, Al-doped ZnO thin films were fabricated by radio frequency (RF) magnetron sputtering technology and deposited on polyimide and glass substrates. Under different Ar flow rates varied from 30 to 70 sccm, the band gap of thin films were changed from 3.56 to 3.67 eV. As sputtering power ranged from 125 to 200 W, the band gap was varied from 3.28 to 3.82 eV; the band gap was between 3.41 and 3.88 eV as substrate temperature increases from 150℃ to 300℃. Furthermore, the correlation between carrier concentration and band gap was investigated by HALL. These results demonstrate that the band gap of the Al-doped ZnO thin film can be adjusted by changing the Ar flow rate, sputtering power and substrate temperature, which can improve the performance of semiconductor devices related to Al-doped ZnO thin film.

  12. Environmentally induced chemical and morphological heterogeneity of zinc oxide thin films

    Science.gov (United States)

    Jiang, Hua; Chou, Kang Wei; Petrash, Stanislas; Williams, Garth; Thieme, Juergen; Nykypanchuk, Dmytro; Li, Li; Muto, Atsushi; Chen-Wiegart, Yu-chen Karen

    2016-08-01

    Zinc oxide (ZnO) thin films have been reported to suffer from degradation in electrical properties, when exposed to elevated heat and humidity, often leading to failures of electronic devices containing ZnO films. This degradation appears to be linked to water and oxygen penetration into the ZnO film. However, a direct observation in the ZnO film morphological evolution detailing structural and chemical changes has been lacking. Here, we systematically investigated the chemical and morphological heterogeneities of ZnO thin films caused by elevated heat and humidity, simulating an environmental aging. X-ray fluorescence microscopy, X-ray absorption spectroscopy, grazing incidence small angle and wide angle X-ray scattering, scanning electron microscopy (SEM), ultra-high-resolution SEM, and optical microscopy were carried out to examine ZnO and Al-doped ZnO thin films on two different substrates—silicon wafers and flexible polyethylene terephthalate (PET) films. In the un-doped ZnO thin film, the simulated environmental aging is resulting in pin-holes. In the Al-doped ZnO thin films, significant morphological changes occurred after the treatment, with an appearance of platelet-shaped structures that are 100-200 nm wide by 1 μm long. Synchrotron x-ray characterization further confirmed the heterogeneity in the aged Al-doped ZnO, showing the formation of anisotropic structures and disordering. X-ray diffraction and X-ray absorption spectroscopy indicated the formation of a zinc hydroxide in the aged Al-doped films. Utilizing advanced characterization methods, our studies provided information with an unprecedented level of details and revealed the chemical and morphologically heterogeneous nature of the degradation in ZnO thin films.

  13. Environmentally induced chemical and morphological heterogeneity of zinc oxide thin films

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Hua [Department of Materials Science and Engineering, Stony Brook University, Stony Brook, New York 11790 (United States); Chou, Kang Wei [Henkel Ibérica S. A. Edificio Eureka, 08193, Campus UAB, Barcelona (Spain); Petrash, Stanislas [Henkel Corporation, 10 Finderne Avenue, Bridgewater, New Jersey 08807 (United States); Williams, Garth; Thieme, Juergen; Li, Li; Chen-Wiegart, Yu-chen Karen, E-mail: ycchen@bnl.gov [National Synchrotron Light Source II, Brookhaven National Laboratory, 743 Brookhaven Avenue, Upton, New York 11973-5000 (United States); Nykypanchuk, Dmytro [Center for Functional Nanomaterials, Brookhaven National Laboratory, 735 Brookhaven Avenue, Upton, New York 11973-5000 (United States); Muto, Atsushi [Hitachi High Technologies America, 22610 Gateway Center Drive, Clarksburg, Maryland 20871 (United States)

    2016-08-29

    Zinc oxide (ZnO) thin films have been reported to suffer from degradation in electrical properties, when exposed to elevated heat and humidity, often leading to failures of electronic devices containing ZnO films. This degradation appears to be linked to water and oxygen penetration into the ZnO film. However, a direct observation in the ZnO film morphological evolution detailing structural and chemical changes has been lacking. Here, we systematically investigated the chemical and morphological heterogeneities of ZnO thin films caused by elevated heat and humidity, simulating an environmental aging. X-ray fluorescence microscopy, X-ray absorption spectroscopy, grazing incidence small angle and wide angle X-ray scattering, scanning electron microscopy (SEM), ultra-high-resolution SEM, and optical microscopy were carried out to examine ZnO and Al-doped ZnO thin films on two different substrates—silicon wafers and flexible polyethylene terephthalate (PET) films. In the un-doped ZnO thin film, the simulated environmental aging is resulting in pin-holes. In the Al-doped ZnO thin films, significant morphological changes occurred after the treatment, with an appearance of platelet-shaped structures that are 100–200 nm wide by 1 μm long. Synchrotron x-ray characterization further confirmed the heterogeneity in the aged Al-doped ZnO, showing the formation of anisotropic structures and disordering. X-ray diffraction and X-ray absorption spectroscopy indicated the formation of a zinc hydroxide in the aged Al-doped films. Utilizing advanced characterization methods, our studies provided information with an unprecedented level of details and revealed the chemical and morphologically heterogeneous nature of the degradation in ZnO thin films.

  14. Effects of doping concentration on properties of Mn-doped ZnO thin films

    Institute of Scientific and Technical Information of China (English)

    Gao Li; Zhang Jian-Min

    2009-01-01

    This paper reports that the radio frequency magnetron sputtering is used to fabricate ZnO and Mn-doped ZnO thin films on glass substrates at 500 ℃. The Mn-doped ZnO thin films present wurtzite structure of ZnO and have a smoother surface, better conductivity but no ferromagnetism. The x-ray photoelectron spectroscopy results show that the binding energy of Mn_(2p3/2) increases with increasing Mn content slightly, and the state of Mn in the Mn-doped ZnO thin films is divalent. The chemisorbed oxygen in the Mn-doped ZnO thin films increases with increasing Mn doping concentration. The photoluminescence spectra of ZnO and Mn-doped ZnO thin films have a similar ultraviolet emission. The yellow green emissions of 4 wt. % and 10 wt. % Mn-doped thin films are quenched, whereas the yellow green emission occurs because of abundant oxygen vacancies in the Mn-doped ZnO thin films after 20 wt. % Mn doping. Compared with pure ZnO thin film, the bandgap of the Mn-doped ZnO thin films increases with increasing Mn content.

  15. Improved conversion efficiency of amorphous Si solar cells using a mesoporous ZnO pattern

    Science.gov (United States)

    Go, Bit-Na; Kim, Yang Doo; suk Oh, Kyoung; Kim, Chaehyun; Choi, Hak-Jong; Lee, Heon

    2014-09-01

    To provide a front transparent electrode for use in highly efficient hydrogenated amorphous silicon (a-Si:H) thin-film solar cells, porous flat layer and micro-patterns of zinc oxide (ZnO) nanoparticle (NP) layers were prepared through ultraviolet nanoimprint lithography (UV-NIL) and deposited on Al-doped ZnO (AZO) layers. Through this, it was found that a porous micro-pattern of ZnO NPs dispersed in resin can optimize the light-trapping pattern, with the efficiency of solar cells based on patterned or flat mesoporous ZnO layers increased by 27% and 12%, respectively.

  16. Mn doped nanostucture ZnO thin film for photo sensor and gas sensor application

    Science.gov (United States)

    Mahajan, Sandip V.; Upadhye, Deepak S.; Shaikh, Shahid U.; Birajadar, Ravikiran B.; Siddiqui, Farha Y.; Ghule, Anil V.; Sharma, Ramphal

    2013-02-01

    Mn doped nanostructure ZnO thin film prepared by soft chemically route method. ZnO thin films were deposited on glass substrate by successive ionic layer adsorption and reaction technique (SILAR). After deposit ZnO thin film dipped in MnSO4 solution for 1 min. The optical properties as absorbance were determined using UV-Spectrophotometer and band gap was also calculated. The Structural properties were studied by XRD. The improvement in gas sensing properties was found to enhance after doping of Mn on ZnO thin film. The Photo Sensor nature was calculated by I-V characteristics.

  17. Crystallinity Improvement of ZnO Thin Film on Different Buffer Layers Grown by MBE

    OpenAIRE

    2012-01-01

    The material and optical properties of ZnO thin film samples grown on different buffer layers on sapphire substrates through a two-step temperature variation growth by molecular beam epitaxy were investigated. The thin buffer layer between the ZnO layer and the sapphire substrate decreased the lattice mismatch to achieve higher quality ZnO thin film growth. A GaN buffer layer slightly increased the quality of the ZnO thin film, but the threading dislocations still stretched along the c-axis o...

  18. Optical characterization of ZnO thin films deposited by RF magnetron sputtering method

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    This study investigated the process parameter effects on the structural and optical properties of ZnO thin film using radio frequency (RF) magnetron sputtering on amorphous glass substrates. The process parameters included RF power and working pressure. Results show that RF power was increased to promote the crystalline quality and decrease ZnO thin film defects. However, when the working pressure was increased to 3 Pa the ZnO thin film crystalline quality became worse. At a 200 W RF power and 1 Pa working pressure, the ZnO thin film with an optical band gap energy of 3.225 eV was obtained.

  19. Single-Crystal Mesoporous ZnO Thin Films Composed of Nanowalls

    KAUST Repository

    Wang, Xudong

    2009-02-05

    This paper presents a controlled, large scale fabrication of mesoporous ZnO thin films. The entire ZnO mesoporous film is one piece of a single crystal, while high porosity made of nanowalls is present. The growth mechanism was proposed in comparison with the growth of ZnO nanowires. The ZnO mesoporous film was successfully applied as a gas sensor. The fabrication and growth analysis of the mesoporous ZnO thin film gi ve general guidance for the controlled growth of nanostructures. It also pro vides a unique structure with a superhigh surface-to-volume ratio for surface-related applications. © 2009 American Chemical Society.

  20. Effects of concentration of reduced graphene oxide on properties of sol–gel prepared Al-doped zinc oxide thin films

    Energy Technology Data Exchange (ETDEWEB)

    Chou, Ching-Tian; Wang, Fang-Hsing, E-mail: fansen@dragon.nchu.edu.tw; Chen, Wei-Chun

    2016-04-30

    Reduced-graphene-oxide-incorporated aluminum-doped zinc oxide (AZO:rGO) composite thin films were synthesized on glass substrates by using the sol–gel method. The effect of the rGO concentration (0–3 wt%) on structural, electrical, and optical properties of the composite film was investigated by X-ray diffraction, scanning electron microscopy, atomic force microscopy, Hall-effect measurement, and ultraviolet–visible spectrometry. All of the composite films showed a typical hexagonal wurtzite structure, and the films incorporated with 1 wt% rGO showed the highest (0 0 2) peak intensity. The sheet resistance of the films was effectively reduced by a factor of more than two as the rGO ratio increased from 0 to 1 wt%. However, the sheet resistance increased with a further increase in the rGO ratio. The optical transmittance of the composite film monotonically decreased with increasing the rGO ratio from 0 to 3 wt%. The average optical transmittance (400–700 nm) of the AZO:rGO thin film within 1 wt% rGO was above 81%. - Highlights: • Reduced-graphene-oxide-doped ZnO:Al composite films are synthesized by sol–gel. • All AZO:rGO thin films show a typical hexagonal wurtzite structure. • Sheet resistance of AZO:rGO(1 wt%) film decreases by a factor of more than two. • The average visible transmittance of the AZO:rGO(1 wt%) film was 81%.

  1. Appraisal on Textured Grain Growth and Photoconductivity of ZnO Thin Film SILAR

    Directory of Open Access Journals (Sweden)

    Deepu Thomas

    2014-01-01

    Full Text Available ZnO thin films were prepared by successive ionic layer adsorption reaction (SILAR method. The textured grain growth along c-axis in pure ZnO thin films and doped with Sn was studied. The structural analysis of the thin films was done by X-ray diffraction and surface morphology by scanning electron microscopy. Textured grain growth of the samples was measured by comparing the peak intensities. Textured grain growth and photo current in ZnO thin films were found to be enhanced by doping with Sn. ZnO thin film having good crystallinity with preferential (002 orientation is a semiconductor with photonic properties of potential benefit to biophotonics. From energy dispersive X-ray analysis, it is inferred that oxygen vacancy creation is responsible for the enhanced textured grain growth in ZnO thin films.

  2. Two different mechanisms on UV emission enhancement in Ag-doped ZnO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Linhua, E-mail: congyu3256@tom.com [School of Physics and Optoelectronic Engineering, Nanjing University of Information Science and Technology, Nanjing 210044 (China); Optics and Photonic Technology Laboratory, Nanjing University of Information Science and Technology, Nanjing 210044 (China); Zheng, Gaige; Zhao, Lilong; Pei, Shixin [School of Physics and Optoelectronic Engineering, Nanjing University of Information Science and Technology, Nanjing 210044 (China); Optics and Photonic Technology Laboratory, Nanjing University of Information Science and Technology, Nanjing 210044 (China)

    2015-02-15

    Ag-doped ZnO thin films were prepared by a sol–gel method. The structural, morphological and optical properties of the samples were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), UV–vis and photoluminescence spectra. The results show that the Ag in the ZnO thin films annealed at 500 °C for 1 h substitutes for Zn and exists in the form of Ag{sup +} ion (Ag{sub Zn}) while the Ag in the ZnO thin films without a post-annealing mainly exists in the form of simple substance (Ag{sup 0}). The incorporation of Ag indeed can improve the ultraviolet emission of ZnO thin films and suppress the visible emissions at the same time. However, the mechanisms on the ultraviolet emission enhancement in the annealed and unannealed Ag-doped ZnO thin films are very different. As for the post-annealed Ag-doped ZnO thin films, the UV emission enhancement maybe mainly results from more electron–hole pairs (excitons) due to Ag-doping while for the unannealed Ag-doped ZnO thin films; the UV emission enhancement is attributed to the resonant coupling between exciton emission in ZnO and localized surface plasmon in Ag nanoparticles. - Highlights: • Ag-doped ZnO thin films have been prepared by the sol–gel method. • Ag-doping can enhance ultraviolet emission of ZnO thin films and depress the visible emissions at the same time. • There are two different mechanisms on UV emission enhancement in Ag-doped ZnO thin films. • The UV emission enhancement from the resonant coupling between excitonic emissions and localized surface plasmon in Ag nanoparticle is very attractive.

  3. Ultraviolet emission enhancement in ZnO thin films modified by nanocrystalline TiO2

    Science.gov (United States)

    Zheng, Gaige; Lu, Xi; Qian, Liming; Xian, Fenglin

    2017-05-01

    In this study, nanocrystalline TiO2 modified ZnO thin films were prepared by electron beam evaporation. The structural, morphological and optical properties of the samples were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), UV-visible spectroscopy, fluorescence spectroscopy, respectively. The composition of the films was examined by energy dispersive X-ray spectroscopy (EDX). The photoluminescent spectrum shows that the pure ZnO thin film exhibits an ultraviolet (UV) emission peak and a strong green emission band. Surface analysis indicates that the ZnO thin film contains many oxygen vacancy defects on the surface. After the ZnO thin film is modified by the nanocrystalline TiO2 layer, the UV emission of ZnO is largely enhanced and the green emission is greatly suppressed, which suggests that the surface defects such as oxygen vacancies are passivated by the TiO2 capping layer. As for the UV emission enhancement of the ZnO thin film, the optimized thickness of the TiO2 capping layer is ∼16 nm. When the thickness is larger than 16 nm, the UV emission of the ZnO thin film will decrease because the TiO2 capping layer absorbs most of the excitation energy. The UV emission enhancement in the nanocrystalline TiO2 modified ZnO thin film can be attributed to surface passivation and flat band effect.

  4. Influence of Al concentration and annealing temperature on structural, optical, and electrical properties of Al co-doped ZnO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Gürbüz, Osman [Department of Physics, Yıldız Technical University, Davutpaşa, 34210 İstanbul (Turkey); Kurt, İsmail; Çalışkan, Serkan [Department of Physics, Fatih University, Büyükçekmece, 34500 İstanbul (Turkey); Güner, Sadık, E-mail: sguner@fatih.edu.tr [Department of Physics, Fatih University, Büyükçekmece, 34500 İstanbul (Turkey)

    2015-09-15

    Highlights: • RF magnetron sputtering technique seems to be very efficient method for fabrication of Al doped ZnO (AZO) films. • Long range single crystalline structure improves with annealing process. • Optical properties became much better after annealing process especially for the AZO films that include high Al concentration. • Much greater conductivity with increasing Al concentration and annealing process. • AZO films have potential applicability in spintronic devices. - Abstract: The pure ZnO and Al-doped ZnO (AZO) thin films (thickness: 200 nm) were prepared on both side polished silica (SiO{sub 2}) substrates via RF magnetron sputtering at room temperature by using 2.5 inches high-purity ZnO (99.9%) and Al (99.9%) targets. The samples were annealed at 300 °C, 400 °C and 500 °C for 45 min in N{sub 2} ambient in quartz annealing furnace system, respectively. We investigated the effects of various Al concentrations and annealing treatment on the structural, electrical, and optical properties of films. The preferred crystallization was observed along c axis (single (0 0 2) diffraction peak) from substrate surface assigning the single crystalline Würtzite lattice for pure ZnO and AZO thin films. Although increasing Al concentration decreases the order of crystallization of as-grown films, annealing process increases the long range crystal order. The crystallite sizes vary between minimum 12.98 nm and maximum 20.79 nm for as-grown and annealed samples. The crystallite sizes decrease with increasing Al concentration but increase with increasing annealing temperature as general trend. The grain size and porosity of films change with annealing treatment. The smaller grains coalesce together to form larger grains for many films. However, a reverse behavior is seen for Al{sub 2.23}ZnO and Al{sub 12.30}ZnO samples. That is, Al concentration plays critical role as well as temperature on grain size. Low percent optical transmittance (T%) is observed due to

  5. Al-doped and undoped zinc oxide films obtained by soft chemistry

    Directory of Open Access Journals (Sweden)

    Suzana M. Mihaiu

    2009-06-01

    Full Text Available Zinc oxide with a hexagonal wurzite type structure is an unique material that exhibits semiconducting, piezoelectric and pyroelectric properties. These properties play a key role for applications in optoelectronic devices. In the present work Al-doped and undoped ZnO films were obtained by soft chemistry starting with zinc acetate dihydrate and Al(III isopropoxide in absolute ethyl alcohol. Trietanolamine was used as chelating agent. The fi lms were deposited by dip coating technique on the silicon substrate and thermally treated at 500°C for one hour. The morphological characteristics of the films were investigated by Atomic Force Microscopy (AFM. Optical constants, such as refractive index (n and extinction coeffi cient (k, were established by Spectroellipsometry measurements. Electrical conductivity of the studied fi lms was determined in the 20–500°C temperature range by “the four point method”. The morphology of the fi lms is infl uenced by the starting sol composition, as found from AFM. According to the ellipsometric spectral data, more porous and thinner films, with smaller refractive index were obtained in the case of Al-doped ZnO fi lms as compared with ZnO films. Both ZnO and Al-doped ZnO fi lms presented high electrical resistivity.

  6. Al-doped ZnO/Ag grid hybrid transparent conductive electrodes fabricated using a low-temperature process

    Energy Technology Data Exchange (ETDEWEB)

    An, Ha-Rim; Oh, Sung-Tag [Department of Materials Science and Engineering, Seoul National University of Science and Technology, Seoul 139-743 (Korea, Republic of); Kim, Chang Yeoul [Future Convergence Ceramic Division, Korea Institute Ceramic Engineering and Technology (KICET), Seoul 233-5 (Korea, Republic of); Baek, Seong-Ho [Energy Research Division, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 711-873 (Korea, Republic of); Park, Il-Kyu, E-mail: ikpark@ynu.ac.kr [Department of Electronic Engineering, Yeungnam University, Gyeongbuk 712-749 (Korea, Republic of); Ahn, Hyo-Jin, E-mail: hjahn@seoultech.ac.kr [Department of Materials Science and Engineering, Seoul National University of Science and Technology, Seoul 139-743 (Korea, Republic of)

    2014-12-05

    Highlights: • Al-doped ZnO/Ag transparent conductive electrode is fabricated at low temperature. • Performance of the hybrid transparent conductive electrode affected by the structure. • The performance enhancement mechanism is suggested. - Abstract: Al-doped ZnO (AZO)/Ag grid hybrid transparent conductive electrode (TCE) structures were fabricated at a low temperature by using electrohydrodynamic jet printing for the Ag grids and atomic layer deposition for the AZO layers. The structural investigations showed that the AZO/Ag grid hybrid structures consisted of Ag grid lines formed by Ag particles and the AZO layer covering the inter-spacing between the Ag grid lines. The Ag particles comprising the Ag grid lines were also capped by thin AZO layers, and the coverage of the AZO layers was increased with increasing the thickness of the AZO layer. Using the optimum thickness of AZO layer of 70 nm, the hybrid TCE structure showed an electrical resistivity of 5.45 × 10{sup −5} Ω cm, an optical transmittance of 80.80%, and a figure of merit value of 1.41 × 10{sup −2} Ω{sup −1}. The performance enhancement was suggested based on the microstructural investigations on the AZO/Ag grid hybrid structures.

  7. Appraisal on Textured Grain Growth and Photoconductivity of ZnO Thin Film SILAR

    OpenAIRE

    Deepu Thomas; Sunil C. Vattappalam; Sunny Mathew; Simon Augustine

    2014-01-01

    ZnO thin films were prepared by successive ionic layer adsorption reaction (SILAR) method. The textured grain growth along c-axis in pure ZnO thin films and doped with Sn was studied. The structural analysis of the thin films was done by X-ray diffraction and surface morphology by scanning electron microscopy. Textured grain growth of the samples was measured by comparing the peak intensities. Textured grain growth and photo current in ZnO thin films were found to be enhanced by doping with S...

  8. Effective conductivity of chemically deposited ZnO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Robles, M. [Universidad Autonoma del Estado de Morelos (UAEM), Cuernavaca (Mexico). Fac. de Ciencias; Tagueena-Martinez, J. [IIM-UNAM, Temixco, Morelos (Mexico). Lab. de Energia Solar; Del Rio, J.A. [IIM-UNAM, Temixco, Morelos (Mexico). Lab. de Energia Solar

    1997-01-30

    Chemically deposited thin films have multiple applications. However, as a result of their complex structure, their physical properties are very difficult to predict. In this paper, we use an effective medium approach to model these heterogeneous systems. We extend Thorpe`s formula for the effective electrical conductivity of elliptical holes randomly distributed in a matrix to a system composed of conducting ellipses in a conducting matrix. This extension is used to calculate the effective electrical conductivity of polycrystalline chemically deposited ZnO thin films. We compare experimental results obtained by two different deposition methods: spray pyrolysis and successive ion layer adsorption and reaction (SILAR) reported here. We select the elliptical geometric parameters from microstructural data. Good agreement between the experimental measurements and our calculation is obtained. In addition, we present a new proof of the reciprocity theorem used to derive the theoretical relation. (orig.)

  9. The Electrical Characteristics of Aluminium Doped Zinc Oxide Thin Film for Humidity Sensor Applications

    Directory of Open Access Journals (Sweden)

    N. D. Md Sin

    2011-01-01

    Full Text Available The electrical characteristics of aluminum (Al doped zinc oxide (ZnO thin film for high sensitivity humidity sensors are presented. The effects of Al doping concentration at 0∼0.6 at % on the Al doped ZnO thin film properties were investigated using current-voltage measurement. The optical and structural properties were characterized using photoluminescence (PL, scanning emission microscope (SEM, and X-ray diffraction (XRD. Parameter 0.6 at % Aluminum doped show high sensitivity and suitable for humidity sensor. PL show an emissions band with two peaks centered at about 380 nm (ultra-violet (UV and 600 nm (green in a room temperature. The length of the nanorods increases as the doping concentration increases. XRD results show the intensity of the (002 peak decreased with the increasing of doping concentration.

  10. Synthesis and annealing study of RF sputtered ZnO thin film

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Shushant Kumar, E-mail: singhshushant86@gmail.com; Sharma, Himanshu [Department of Physics, Malaviya National Institute of Technology, Jaipur, JLN Marg, Malaviya Nagar, Jaipur-302017 (India); Singhal, R. [Department of Physics and Materials Research Centre, Malaviya National Institute of Technology Jaipur, JLN Marg, Malaviya Nagar, Jaipur-302017 (India); Kumar, V. V. Siva; Avasthi, D. K. [Inter-University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi-110067 (India)

    2016-05-23

    In this paper, we have investigated the annealing effect on optical and structural properties of ZnO thin films, synthesized by RF magnetron sputtering. ZnO thin films were deposited on glass and silicon substrates simultaneously at a substrate temperature of 300 °C using Argon gas in sputtering chamber. Thickness of as deposited ZnO thin film was found to be ~155 nm, calculated by Rutherford backscattering spectroscopy (RBS). These films were annealed at 400 °C and 500 °C temperature in the continuous flow of oxygen gas for 1 hour in tube furnace. X-ray diffraction analysis confirmed the formation of hexagonal wurtzite structure of ZnO thin film along the c-axis (002) orientation. Transmittance of thin films was increased with increasing the annealing temperature estimated by UV-visible transmission spectroscopy. Quality and texture of the thin films were improved with annealing temperature, estimated by Raman spectroscopy.

  11. Synthesis and annealing study of RF sputtered ZnO thin film

    Science.gov (United States)

    Singh, Shushant Kumar; Sharma, Himanshu; Singhal, R.; Kumar, V. V. Siva; Avasthi, D. K.

    2016-05-01

    In this paper, we have investigated the annealing effect on optical and structural properties of ZnO thin films, synthesized by RF magnetron sputtering. ZnO thin films were deposited on glass and silicon substrates simultaneously at a substrate temperature of 300 °C using Argon gas in sputtering chamber. Thickness of as deposited ZnO thin film was found to be ~155 nm, calculated by Rutherford backscattering spectroscopy (RBS). These films were annealed at 400 °C and 500 °C temperature in the continuous flow of oxygen gas for 1 hour in tube furnace. X-ray diffraction analysis confirmed the formation of hexagonal wurtzite structure of ZnO thin film along the c-axis (002) orientation. Transmittance of thin films was increased with increasing the annealing temperature estimated by UV-visible transmission spectroscopy. Quality and texture of the thin films were improved with annealing temperature, estimated by Raman spectroscopy.

  12. Analysis of Li-related defects in ZnO thin films influenced by annealing ambient

    Indian Academy of Sciences (India)

    Bing Wang; Lidan Tang

    2014-02-01

    Li-doped ZnO thin films were grown on quartz substrates by radio frequency magnetron sputtering and in situ annealing under O2 or Ar ambient. Li-related defects in ZnO films strongly depend on the annealing ambient. AFM and XRD indicated that ZnO films possessed a good crystallinity with -axis orientation, uniform thickness and dense surface. Electrical and optical properties demonstrated that, an amount of LiZn defect had existed in ZnO annealed under O2 ambient and an amount of Lii(o) defect had existed in ZnO annealed under Ar ambient. First-principle calculations were performed to calculate formation energies of Li-doped ZnO in order to explain the formation mechanism of Li-related defects in ZnO.

  13. Oriented grain growth in ZnO thin films by Iodine doping

    Science.gov (United States)

    Thomas, Deepu; Vattappalam, Sunil C.; Mathew, Sunny; Augustine, Simon

    2015-02-01

    ZnO thin films were prepared by Successive Ionic Layer Adsorption Reaction (SILAR) method. Oriented grain growth in Iodine doped ZnO thin films were studied. The oriented grain growth in samples was studied by comparing the peak intensities from X-ray diffraction data and surface morphology by scanning electron microscopy. It is found that oriented grain growth significantly enhanced by Iodine doping. When the oriented grain growth increases, crystallinity of the thin film improves, resistance and band gap decrease. ZnO thin films having good crystallinity with preferential (002) orientation is a prerequisite for the fabrication of devices like UV diode lasers, acoustic- optic devices etc. A possible mechanism for the oriented grain growth is also investigated. It is inferred that creation of point defects is responsible for the enhanced oriented grain growth in ZnO thin films when doped with iodine.

  14. Macroparticles Reduction Using Filter Free Cathodic Vacuum Arc Deposition Method in ZnO Thin Films.

    Science.gov (United States)

    Yuvakkumar, R; Peranantham, P; Nathanael, A Joseph; Nataraj, D; Mangalaraj, D; Hong, Sun Ig

    2015-03-01

    We report a new method to reduce macroparticles in ZnO thin films using filter free cathodic vacuum arc deposition without using any cooling arrangements operated at low arc current. The detailed mechanism has been proposed to reduce macroparticles during thin film deposition. The successful reduction of macroparticles was confirmed employing FESEM-EDX studies. FESEM images of ZnO thin films deposited with cathode spot to substrate distance from 10 to 20 cm revealed that the population of the macroparticles were reduced with the increase of cathode spot to substrate distances at low arc current. The prepared ZnO films were characterised and showed good structural and optical properties.

  15. Harmonic generation in ZnO nanocrystalline laser deposited thin films

    Science.gov (United States)

    Narayanan, V.; Thareja, R. K.

    2006-04-01

    ZnO plasma produced by third harmonic 355 nm of Nd:YAG laser at various ambient pressures of oxygen was used for depositing quality nanocrystalline ZnO thin films. Time and space resolved optical emission spectroscopy is used to correlate the plasma properties with that of deposited thin films. The deposited films showed particle size of 8 and 84 nm at ambient oxygen pressure of 100 and 900 mTorr, respectively. Third harmonic generation observed in ZnO thin films deposited under 100 mTorr of ambient oxygen is reported.

  16. Direct current magnetron sputter-deposited ZnO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Hoon, Jian-Wei [Faculty of Engineering, Multimedia University, Persiaran Multimedia, 63100 Cyberjaya, Selangor (Malaysia); Chan, Kah-Yoong, E-mail: kychan@mmu.edu.my [Faculty of Engineering, Multimedia University, Persiaran Multimedia, 63100 Cyberjaya, Selangor (Malaysia); Krishnasamy, Jegenathan; Tou, Teck-Yong [Faculty of Engineering, Multimedia University, Persiaran Multimedia, 63100 Cyberjaya, Selangor (Malaysia); Knipp, Dietmar [School of Engineering and Science, Jacobs University Bremen, 28759 Bremen (Germany)

    2011-01-15

    Zinc oxide (ZnO) is a very promising electronic material for emerging transparent large-area electronic applications including thin-film sensors, transistors and solar cells. We fabricated ZnO thin films by employing direct current (DC) magnetron sputtering deposition technique. ZnO films with different thicknesses ranging from 150 nm to 750 nm were deposited on glass substrates. The deposition pressure and the substrate temperature were varied from 12 mTorr to 25 mTorr, and from room temperature to 450 deg. C, respectively. The influence of the film thickness, deposition pressure and the substrate temperature on structural and optical properties of the ZnO films was investigated using atomic force microscopy (AFM) and ultraviolet-visible (UV-Vis) spectrometer. The experimental results reveal that the film thickness, deposition pressure and the substrate temperature play significant role in the structural formation and the optical properties of the deposited ZnO thin films.

  17. Optoelectronic properties of doped hydrothermal ZnO thin films

    KAUST Repository

    Mughal, Asad J.

    2017-03-10

    Group III impurity doped ZnO thin films were deposited on MgAl2O3 substrates using a simple low temperature two-step deposition method involving atomic layer deposition and hydrothermal epitaxy. Films with varying concentrations of either Al, Ga, or In were evaluated for their optoelectronic properties. Inductively coupled plasma atomic emission spectroscopy was used to determine the concentration of dopants within the ZnO films. While Al and Ga-doped films showed linear incorporation rates with the addition of precursors salts in the hydrothermal growth solution, In-doped films were shown to saturate at relatively low concentrations. It was found that Ga-doped films showed the best performance in terms of electrical resistivity and optical absorbance when compared to those doped with In or Al, with a resistivity as low as 1.9 mΩ cm and an optical absorption coefficient of 441 cm−1 at 450 nm.

  18. Photocatalytic and optical properties of nanocomposite TiO2-ZnO thin films

    Science.gov (United States)

    Mohamed, S. H.; El-Hagary, M.; Althoyaib, S.

    2012-01-01

    Nanocomposite TiO2-ZnO thin films, with different ZnO content, were deposited by electron-beam evaporation on glass and Si(1 0 0) substrates. The resulting films were annealed in air for 1 h at 450 °C. X-ray diffraction revealed the presence of monoclinic β-TiO2 and hexagonal ZnO for the films prepared with ZnO content of 0 at.% and 100 at.%, respectively. Mixed monoclinic β-TiO2 and hexagonal ZnO phases were observed at higher ZnO content between 50 at.% and 85 at.%. Spectroscopic ellipsometry (SE) was employed to determine the film thickness and optical constants. A two-layer model was used to describe the experimental ellipsometric data. At any wavelength longer than 390 nm, the refractive index decreases gradually with increasing ZnO content in the composite films. The optical band gap increased with increasing ZnO content. The photocatalytic behavior of TiO2-ZnO thin films was mainly evaluated by measuring the decomposition of methylene blue. The nanocomposite film with ZnO content of 8 at.% has the best photocatalytic activities.

  19. Crystallographic polarity effect of ZnO on thin film growth of pentacene

    Science.gov (United States)

    Nakamura, Tatsuru; Nagata, Takahiro; Hayakawa, Ryoma; Yoshimura, Takeshi; Oh, Seungjun; Hiroshiba, Nobuya; Chikyow, Toyohiro; Fujimura, Norifumi; Wakayama, Yutaka

    2017-04-01

    The spontaneous polarization effect of ZnO on the thin film growth of pentacene, which is a typical π conjunction organic semiconductor, was investigated. Pentacene thin films were grown on polar ZnO surfaces by ultraslow organic film physical vapor deposition to obtain layer-by-layer growth. X-ray diffraction measurements revealed that pentacene molecules stand upright on polar ZnO surfaces, and that the films consist of two polymorphs, namely, the thin-film and bulk phases. The thin-film phases of pentacene were observed regardless of the polarity of the ZnO substrate at a thickness of less than six molecular layers. However, pentacene on a Zn-polar ZnO substrate gradually changed to the bulk phase unlike that on an O-polar ZnO substrate. Kelvin probe force microscopy measurements revealed that the surface potential of pentacene becomes more positive with increasing pentacene thickness at less than two molecular layers. The variation in the potential of pentacene on the Zn-polar ZnO substrate was larger than that of pentacene on the O-polar ZnO substrate. These findings indicate that the polarity of the semiconductor can control the growth and electronic state of the inorganic/organic semiconductor interface.

  20. Properties of multilayer gallium and aluminum doped ZnO(GZO/AZO)transparent thin films deposited by pulsed laser deposition process

    Institute of Scientific and Technical Information of China (English)

    Jin-Hyum SHIN; Dong-Kyun SHIN; Hee-Young LEE; Jai-Yeoul LEE

    2011-01-01

    Multilayer gallium and aluminum doped ZnO (GZO/AZO) films were fabricated by alternative deposition of Ga-doped zinc oxide(GZO) and Al-doped zinc oxide(AZO) thin film by using pulsed laser deposition(PLD) process. The electrical and optical properties of these GZO/AZO thin films were investigated and compared with those of GZO and AZO thin films. The GZO/AZO GZO/AZO thin films linearly decreases with increasing the Al ratio.

  1. Optical characterization of ZnO thin films deposited by RF magnetron sputtering method

    Institute of Scientific and Technical Information of China (English)

    TANG Ning; WANG JinLiang; XU HengXing; PENG HongYong; FAN Chao

    2009-01-01

    This study investigated the process parameter effects on the structural and optical properties of ZnO thin film using radio frequency(RF)magnetron sputtering on amorphous glass substrates.The process parameters included RF power and working pressure.Results show that RF power was increased to promote the crystalline quality and decrease ZnO thin film defects.However,when the working pressure was increased to 3 Pa the ZnO thin film crystalline quality became worse.At a 200 W RF power and 1 Pa working pressure,the ZnO thin film with an optical band gap energy of 3.225 eV was obtained.

  2. ZnO Thin Films Deposited on Textile Material Substrates for Biomedical Applications

    Science.gov (United States)

    Duta, L.; Popescu, A. C.; Dorcioman, G.; Mihailescu, I. N.; Stan, G. E.; Zgura, I.; Enculescu, I.; Dumitrescu, I.

    We report on the coating with ZnO adherent thin films of cotton woven fabrics by Pulsed laser deposition technique in order to obtain innovative textile materials, presenting protective effects against UV radiations and antifungal action.

  3. Frictional Properties of UV illuminated ZnO Thin Films Grown by Pulsed Laser Deposition

    Science.gov (United States)

    Chiu, Hsiang-Chih; Chang, Huan-Pu; Lo, Fang-Yu; Yeh, Yu-Ting; Department of Physics, National Taiwan Normal University Collaboration

    Zinc Oxide (ZnO) nanostructures have potential applications in nano-electro-mechanical systems (NEMS) due to their unique physical properties. ZnO is also an excellent lubricant and hence a promising candidate for protective coatings in NEMS. By means of atomic force microscopy (AFM), we have investigated the frictional properties of ZnO thin films prepared by pulsed laser deposition technique. In addition, UV illumination is used to convert the surface wettability of ZnO thin films from being more hydrophobic to superhydrophilic via the photo-catalyst effect. We found that the frictional properties of the UV illuminated, superhydrophilic ZnO surface are strongly dependent on the environment humidity. While for hydrophobic ZnO, no such dependence is found. The observed frictional behaviors can be explained by the interplay between the surface roughness, environmental humidity and the presence of nanoscale capillary condensation forming between surface asperities at the tip-ZnO contact. Our results might find applications in future ZnO related NEMS. Frictional Properties of UV illuminated ZnO Thin Films Grown by Pulsed Laser Deposition.

  4. Surface microstructure evolution of highly transparent and conductive Al-doped ZnO thin films and its application in CIGS solar cells

    Science.gov (United States)

    Cheng, Ke; Liu, Jingjing; Jin, Ranran; Liu, Jingling; Liu, Xinsheng; Lu, Zhangbo; Liu, Ya; Liu, Xiaolan; Du, Zuliang

    2017-07-01

    Aluminum-doped zinc oxide (AZO) has attained intensive attention as being a very good transparent conducting oxide for photovoltaic applications. In this work, AZO films have been deposited on glass substrate by radio frequency (RF) magnetron sputtering. The influences of substrate temperatures on morphological, structural, optical and electrical properties of AZO films were systematically investigated. The results indicate that all AZO films have the hexagonal structure with c-axis preferred orientation. Morphological and electrical measurements have revealed that the substrate temperatures have strong influence on the microstructure, optical and electrical properties of AZO films. The AZO film is highly transparent from ultraviolet up to near infrared range with highest average transparency exceeding 83%. The minimum resistivity is as low as 6.1 × 10-4 Ω cm. The carrier concentration and mobility are as high as 3.357 × 1020 cm-3 and 30.48 cm2/Vs, respectively. Finally, the performances of the AZO film are evaluated by its practical application in Cu(In1-xGax)Se2 (CIGS) photovoltaic device as a transparent electrode. Benefited from its highly transparent and conductive feature, the most efficient device reveals an efficiency of 7.8% with a short-circuit current density of 28.99 mA/cm2, an open-circuit voltage of 430 mV, and a fill factor of 62.44 under standard conditions.

  5. Low temperature deposition of bifacial CIGS solar cells on Al-doped Zinc Oxide back contacts

    Science.gov (United States)

    Cavallari, Nicholas; Pattini, Francesco; Rampino, Stefano; Annoni, Filippo; Barozzi, Mario; Bronzoni, Matteo; Gilioli, Edmondo; Gombia, Enos; Maragliano, Carlo; Mazzer, Massimo; Pepponi, Giancarlo; Spaggiari, Giulia; Fornari, Roberto

    2017-08-01

    We report on the fabrication and characterization of Cu(In,Ga)Se2 (CIGS)-based thin film bifacial solar cells using Al-doped ZnO (AZO) as cost-effective and non-toxic transparent back contact. We show that, by depositing both CIGS and AZO by Low Temperature Pulsed Electron Deposition at a maximum temperature of 250 °C, a good ohmic contact is formed between the two layers and good quality solar cells can be fabricated as a result. Photovoltaic efficiencies as high as 9.3% (front illumination), 5.1% (backside illumination) and 11.6% (bifacial illumination) have been obtained so far. These values are remarkably higher than those previously reported in the literature. We demonstrate that this improvement is ascribed to the low-temperature deposition process that avoids the formation of Ga2O3 at the CIGS/AZO interface and favours the formation of a low-resistivity contact in agreement with device simulations.

  6. Surface morphology and photoluminescence properties of ZnO thin films obtained by PLD

    Institute of Scientific and Technical Information of China (English)

    FAN Xi-mei; LIAN Jian-she; GUO Zuo-xing; JIANG Qing

    2005-01-01

    ZnO thin films on Si(111) substrate were deposited by laser ablation of Zn target in oxygen reactive atmosphere, Nd-YAG laser with wavelength of 1 064 nm was used as laser source. XRD and FESEM microscopy were applied to characterize the structure and surface morphology of the deposited ZnO films. The optical properties of the ZnO thin films were characterized by photoluminescence. The UV and deep level (yellow-green) light were observed from the films. The UV light is the intrinsic property and deep level light is attributed to the existence of antisite defects (OZn). The intensity of UV and deep level light depends strongly on the surface morphology and is explained by the surface roughness of ZnO film. A strongly UV emission can be obtained from ZnO film with surface roughness in nanometer range.

  7. Thickness dependency of sol-gel derived ZnO thin films on gas sensing behaviors

    Energy Technology Data Exchange (ETDEWEB)

    Kakati, Nitul; Jee, Seung Hyun; Kim, Su Hyun; Oh, Jun Young; Yoon, Young Soo, E-mail: yoonys@yonsei.ac.k

    2010-10-29

    ZnO thin films were fabricated by a sol-gel method using Zn(CH{sub 3}COO){sub 2}.2H{sub 2}O as starting material in order to prepare an acetone gas sensor. A homogeneous and stable solution was prepared by dissolving the zinc acetate in a solution of ethanol and monoethanolamine. The sol-gel solution is coated on alumina substrates with various thicknesses by spin coating technique and heat treated to grow crystalline ZnO thin films. The effect of thickness on physical and electrical properties of as deposited ZnO thin films has been studied. The as deposited ZnO thin films were characterized by X-ray diffraction spectroscopy, field emission scanning electron microscopy and atomic force microscopy. The root mean square surface roughness factors increase with thickness of the films and found 3.9, 6.6, 9.0, and 11.28 nm for 80-, 220-, 450- and 620-nm-thin films respectively. The activation energies of the films are calculated from the resistance temperature characteristics. The sensitivities of the ZnO films towards the acetone gas were determined at an operating temperature of 200 {sup o}C. The sensitivity towards acetone vapor is strongly depending on surface morphology of the ZnO thin films.

  8. Crystallinity Improvement of ZnO Thin Film on Different Buffer Layers Grown by MBE

    Directory of Open Access Journals (Sweden)

    Shao-Ying Ting

    2012-01-01

    Full Text Available The material and optical properties of ZnO thin film samples grown on different buffer layers on sapphire substrates through a two-step temperature variation growth by molecular beam epitaxy were investigated. The thin buffer layer between the ZnO layer and the sapphire substrate decreased the lattice mismatch to achieve higher quality ZnO thin film growth. A GaN buffer layer slightly increased the quality of the ZnO thin film, but the threading dislocations still stretched along the c-axis of the GaN layer. The use of MgO as the buffer layer decreased the surface roughness of the ZnO thin film by 58.8% due to the suppression of surface cracks through strain transfer of the sample. From deep level emission and rocking curve measurements it was found that the threading dislocations play a more important role than oxygen vacancies for high-quality ZnO thin film growth.

  9. Recent advances in ZnO nanostructures and thin films for biosensor applications: Review

    Energy Technology Data Exchange (ETDEWEB)

    Arya, Sunil K., E-mail: sunilarya333@gmail.com [Bioelectronics Program, Institute of Microelectronics, A-Star 11 Science Park Road, Singapore Science Park II, Singapore 117685 (Singapore); Saha, Shibu [Department of Physics and Astrophysics, University of Delhi, Delhi 110007 (India); Ramirez-Vick, Jaime E. [Engineering Science and Materials Department, University of Puerto Rico, Mayaguez, PR 00681 (United States); Gupta, Vinay [Department of Physics and Astrophysics, University of Delhi, Delhi 110007 (India); Bhansali, Shekhar [Department of Electrical and Computer Engineering, Florida International University, Miami, FL (United States); Singh, Surinder P., E-mail: singh.uprm@gmail.com [National Physical Laboratory, Dr K.S. Krishnan Marg, New Delhi 110012 (India)

    2012-08-06

    Graphical abstract: ZnO nanostructures have shown binding of biomolecules in desired orientation with improved conformation and high biological activity, resulting in enhanced sensing characteristics. Furthermore, their compatibility with complementary metal oxide semiconductor technology for constructing integrated circuits makes them suitable candidate for future small integrated biosensor devices. This review highlights various approaches to synthesize ZnO nanostructures and thin films, and their applications in biosensor technology. Highlights: Black-Right-Pointing-Pointer This review highlights various approaches to synthesize ZnO nanostructures and thin films. Black-Right-Pointing-Pointer Article highlights the importance of ZnO nanostructures as biosensor matrix. Black-Right-Pointing-Pointer Article highlights the advances in various biosensors based on ZnO nanostructures. Black-Right-Pointing-Pointer Article describes the potential of ZnO based biosensor for new generation healthcare devices. - Abstract: Biosensors have shown great potential for health care and environmental monitoring. The performance of biosensors depends on their components, among which the matrix material, i.e., the layer between the recognition layer of biomolecule and transducer, plays a crucial role in defining the stability, sensitivity and shelf-life of a biosensor. Recently, zinc oxide (ZnO) nanostructures and thin films have attracted much interest as materials for biosensors due to their biocompatibility, chemical stability, high isoelectric point, electrochemical activity, high electron mobility, ease of synthesis by diverse methods and high surface-to-volume ratio. ZnO nanostructures have shown the binding of biomolecules in desired orientations with improved conformation and high biological activity, resulting in enhanced sensing characteristics. Furthermore, compatibility with complementary metal oxide semiconductor technology for constructing integrated circuits makes ZnO

  10. Growth and Properties of Cu-based Al-doped ZnO Multilayer Films%Cu基Al掺杂ZnO多层薄膜的生长及其性能

    Institute of Scientific and Technical Information of China (English)

    王钰萍; 吕建国; 叶志镇

    2011-01-01

    Al-doped ZnO/Cu(AZO/Cu) bi-layer,Cu/AZO bi-layer,and AZO/Cu/AZO tri-layer films were prepared on glass substrates by DC magnetron sputtering at different temperatures.Comparative study of electrical and optical properties reveal that AZO/Cu bi-layer film is superior in photoelectric properties to other two kinds of multilayer films,with an optimum growth temperature in the 100-150℃ range.Effects of growth temperature on the structural property and surface morphology of AZO/Cu bi-layer films were further investigated.Moderate growth temperatures could lead to high crystal quality of the films,and therefore improve the photoelectric properties.AZO/Cu bi-layer films grown at 150℃ have the highest figure of merit of 1.11×10-2 Ω-1,with a low sheet resistance of 8.99 Ω/sq,high visible transmittance of 80%,and near infrared reflectance of about 70%.Combination of good transparent-conductive property,excellent near-infrared reflectivity,and low-temperature deposition enable the AZO/Cu bi-layer films to be widely used in various fields such as coated glasses,solar cells,and flat panel displays.%本文采用直流磁控溅射技术在玻璃衬底上制备了AZO/Cu、Cu/AZO和AZO/Cu/AZO三种复合结构多层膜,研究了生长温度对多层膜特性的影响,发现AZO/Cu双层薄膜具有最优的光电性能,其最佳生长温度为100~150℃。文中进一步考察了生长温度对AZO/Cu双层薄膜结构性能和表面形貌的影响,结果表明:合适的生长温度有利于改善AZO/Cu双层薄膜的晶体质量,进而提高其光电性能;150℃下沉积的薄膜具有最佳品质因子1.11×10-2Ω-1,此时方块电阻为8.99Ω/sq,可见光透过率为80%,近红外反射率约70%。本文在较低温度下制备的AZO/Cu双层膜具有较优的透明导电性和良好的近红外反射性,可以广泛应用于镀膜玻璃、太阳能电池、平板显示器等光电领域。

  11. Control al doping Compromiso de Colombia

    Directory of Open Access Journals (Sweden)

    Claudia Prieto

    2015-06-01

    Full Text Available Este documento da a conocer la importante noticia de la aprobación, por parte del Comité Olímpico Internacional (COl, de un laboratorio colombiano, para el control al doping, a la vez que aprovecha la oportunidad para ampliar alguna información sobre este tema.

  12. Enhanced the photocatalytic activity of Ni-doped ZnO thin films: Morphological, optical and XPS analysis

    Science.gov (United States)

    Abdel-wahab, M. Sh.; Jilani, Asim; Yahia, I. S.; Al-Ghamdi, Attieh A.

    2016-06-01

    Pure and Ni-doped ZnO thin films with different concentration of Ni (3.5 wt%, 5 wt%, 7 wt%) were prepared by DC/RF magnetron sputtering technique. The X-rays diffraction pattern showed the polycrystalline nature of pure and Ni-doped ZnO thin films. The surface morphology of pure and Ni doped ZnO thin films were investigated through atomic force microscope, which indicated the increase in the grain dimension and surface roughness with increasing the Ni doping. The UV-Visible transmission spectra showed the decrease in the transmittance of doped ZnO thin films with the incorporation of Ni dopants. The surface and chemical state analysis of pure and Ni doped ZnO thin films were investigated by X-rays photoelectron spectroscopy (XPS). The photocatalytic activities were evaluated by an aqueous solution of methyl green dye. The tungsten lamp of 500 W was used as a source of visible light for photocatalytic study. The degradation results showed that the Ni-doped ZnO thin films exhibit highly enhanced photocatalytic activity as compared to the pure ZnO thin films. The enhanced photocatalytic activities of Ni-doped ZnO thin films were attributed to the enhanced surface area (surface defects), surface roughness and decreasing the band gap of Ni-doped ZnO thin films. Our work supports the applications of thin film metal oxides in waste water treatment.

  13. Effect of silver growth temperature on the contacts between Ag and ZnO thin films

    Institute of Scientific and Technical Information of China (English)

    LI XinKun; LI QingShan; LIANG DeChun; XU YanDong; XIE XiaoJun

    2009-01-01

    Highly c-axis oriented ZnO thin films were deposited on Si substrates by the pulsed laser deposition (PLD) method. At different growth temperatures, 200 nm silver films as the contact metal were depos-ited on the ZnO thin films. The growth temperatures have great influence on the crystal quality of Ag films. Current-voltage characteristics were measured at room temperature. The Schottky contacts be-tween Ag and ZnO thin films were successfully obtained when silver electrodes were deposited at 150℃ and 200℃. Ohmic contacts were formed while the growth temperatures were lower than 150℃ or higher than 200℃. After analysis, the forming of Ag/ZnO Schottky contacts was shown to be dependent on the appearance of the p-type inversion layer at the interface between Ag and ZnO layers.

  14. Effect of silver growth temperature on the contacts between Ag and ZnO thin films

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Highly c-axis oriented ZnO thin films were deposited on Si substrates by the pulsed laser deposition (PLD) method. At different growth temperatures,200 nm silver films as the contact metal were deposited on the ZnO thin films. The growth temperatures have great influence on the crystal quality of Ag films. Current-voltage characteristics were measured at room temperature. The Schottky contacts between Ag and ZnO thin films were successfully obtained when silver electrodes were deposited at 150 ℃ and 200℃. Ohmic contacts were formed while the growth temperatures were lower than 150℃ or higher than 200 ℃. After analysis,the forming of Ag/ZnO Schottky contacts was shown to be dependent on the appearance of the p-type inversion layer at the interface between Ag and ZnO layers.

  15. The Structural and Electrical Properties of Nanostructures ZnO Thin Films on Flexible Substrate

    Directory of Open Access Journals (Sweden)

    Nur Sa’adah Muhamad Sauki

    2017-06-01

    Full Text Available Zinc oxide (ZnO thin films were deposited on Teflon substrates by radio frequency (RF magnetron sputtering method at different substrate temperature. The dependence of residual stress on the substrate temperature was investigated in this work due to the growth process, the bombardment of energetic particles and process heating to the deposited thin films. From field emission scanning electron microscope (FESEM images, samples that deposited at various substrate temperatures consists nano-sized particles. The obtained X-ray diffraction (XRD results, it suggested that ZnO thin film deposited at 40oC with highly c-axis oriented shows unstressed film compared to other thin films. Besides that, the ZnO thin films deposited at 40oC shows improved electrical properties.

  16. Photoluminescence of ZnO thin films deposited at various substrate temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Kao, Kuo-Sheng [Department of Computer and Communication, SHU-TE University, Kaohsiung, Taiwan (China); Shih, Wei-Che [Department of Electrical Engineering, National Sun Yat-Sen University, Kaohsiung, Taiwan (China); Ye, Wei-Tsuen [Department of Computer and Communication, SHU-TE University, Kaohsiung, Taiwan (China); Cheng, Da-Long, E-mail: dlcheng@stu.edu.tw [Department of Computer and Communication, SHU-TE University, Kaohsiung, Taiwan (China)

    2016-04-30

    This study investigated surface acoustic wave devices with an Al/ZnO/Si structure for use in ultraviolet sensors. ZnO thin films were fabricated using a reactive radio frequency magnetron sputtering system. The substrate temperature of ZnO thin films can be varied to obtain highly crystalline properties. The surface morphologies and c-axis preferred orientation of the ZnO thin films were determined using scanning electron microscopy and X-ray diffraction. In addition, bright-field images of ZnO crystallization were investigated using a transmission electron microscope. From photoluminescence analysis, four peaks were obtained at 377.8, 384.9, 391.4, and 403.4 nm. Interdigital transducers of an aluminum electrode were fabricated on the ZnO/Si structure by using a direct current sputtering system and photolithography, combined with the lift-off method, thereby obtaining a surface acoustic wave device. Finally, frequency responses were measured using a network analyzer, and an illuminating test was adopted for the ultraviolet sensor, using a wavelength of 355 nm from a light-emitting diode. The sensitivities of the ultraviolet sensor were also discussed. - Highlights: • The ZnO/Si SAW devices exhibit the Rayleigh and Sezawa modes. • The crystalline of ZnO affects the EHP recombination and generation. • The PL spectrum of ZnO shows Gaussian fitting distributions. • The CTD{sub UV} is influenced by SAW types and ZnO film characteristics.

  17. Textured ZnO thin films by RF magnetron sputtering

    CERN Document Server

    Ginting, M; Kang, K H; Kim, S K; Yoon, K H; Park, I J; Song, J S

    1999-01-01

    Textured thin films ZnO has been successfully grown by rf magnetron sputtering method using a special technique of introducing a small amount of water and methanol on the deposition chamber. The grain size of the textured surface is highly dependent on the argon pressure during the deposition. The pressure in this experiment was varied from 50 mTorr down to 5 mTorr and the highest grain size of the film is obtained at 5 mTorr. The total transmittance of the films are more than 85% in the wavelength of 400 to 800 nm, and haze ratio of about 14% is obtained at 400 nm wavelength. Beside the textured surface, these films also have very low resistivity, which is lower than 1.4x10 sup - sup 3 OMEGA centre dot cm. X-ray analysis shows that the films with textured surface have four diffraction peaks on the direction of (110), (002), (101) and (112), while the non-textured films have only (110) and (002) peaks. Due to the excellent characteristics of this film, it will make the film very good TCO alternatives for the ...

  18. Impact of nanostructured thin ZnO film in ultraviolet protection

    Science.gov (United States)

    Sasani Ghamsari, Morteza; Alamdari, Sanaz; Han, Wooje; Park, Hyung-Ho

    2017-01-01

    Nanoscale ZnO is one of the best choices for ultraviolet (UV) protection, not only because of its antimicrobial properties but also due to its potential application for UV preservation. However, the behavior of nanostructured thin ZnO films and long-term effects of UV-radiation exposure have not been studied yet. In this study, we investigated the UV-protection ability of sol gel-derived thin ZnO films after different exposure times. Scanning electron microscopy, atomic force microscopy, and UV-visible optical spectroscopy were carried out to study the structure and optical properties of the ZnO films as a function of the UV-irradiation time. The results obtained showed that the prepared thin ZnO films were somewhat transparent under the visible wavelength region and protective against UV radiation. The UV-protection factor was 50+ for the prepared samples, indicating that they were excellent UV protectors. The deposited thin ZnO films demonstrated promising antibacterial potential and significant light absorbance in the UV range. The experimental results suggest that the synthesized samples have potential for applications in the health care field. PMID:28096668

  19. Impact of nanostructured thin ZnO film in ultraviolet protection.

    Science.gov (United States)

    Sasani Ghamsari, Morteza; Alamdari, Sanaz; Han, Wooje; Park, Hyung-Ho

    2017-01-01

    Nanoscale ZnO is one of the best choices for ultraviolet (UV) protection, not only because of its antimicrobial properties but also due to its potential application for UV preservation. However, the behavior of nanostructured thin ZnO films and long-term effects of UV-radiation exposure have not been studied yet. In this study, we investigated the UV-protection ability of sol gel-derived thin ZnO films after different exposure times. Scanning electron microscopy, atomic force microscopy, and UV-visible optical spectroscopy were carried out to study the structure and optical properties of the ZnO films as a function of the UV-irradiation time. The results obtained showed that the prepared thin ZnO films were somewhat transparent under the visible wavelength region and protective against UV radiation. The UV-protection factor was 50+ for the prepared samples, indicating that they were excellent UV protectors. The deposited thin ZnO films demonstrated promising antibacterial potential and significant light absorbance in the UV range. The experimental results suggest that the synthesized samples have potential for applications in the health care field.

  20. Synthesis and characterization of ZnO thin film by low cost modified SILAR technique

    Directory of Open Access Journals (Sweden)

    Haridas D. Dhaygude

    2016-03-01

    Full Text Available The ZnO thin film is prepared on Fluorine Tin Oxide (FTO coated glass substrate by using SILAR deposition technique containing ZnSO4.7H2O and NaOH as precursor solution with 150 deeping cycles at 70 °C temperature. Nanocrystalline diamond like ZnO thin film is characterized by different characterization techniques such as X-ray diffraction (XRD, Fourier transform (FT Raman spectrometer, Field Emission Scanning Electron Microscopy (FE-SEM with Energy dispersive X-Ray Analysis (EDAX, optical absorption, surface wettability and photoelectrochemical cell performance measurement. The X-ray diffraction analysis shows that the ZnO thin film is polycrystalline in nature having hexagonal crystal structure. The FT-Raman scattering exhibits a sharp and strong mode at 383 cm−1 which confirms hexagonal ZnO nanostructure. The surface morphology study reveals that deposited ZnO film consists of nanocrystalline diamond like morphology all over the substrate. The synthesized thin film exhibited absorption wavelength around 309 nm. Optical study predicted the direct band gap and band gap energy of this film is found to be 3.66 eV. The photoelectrochemical cell (PEC parameter measurement study shows that ZnO sample confirmed the highest values of, short circuit current (Isc - 629 mAcm−2, open circuit voltage (Voc - 878 mV, fill factor (FF - 0.48, and maximum efficiency (η - 0.89%, respectively.

  1. Ohmic-rectifying conversion of Ni contacts on ZnO and the possible determination of ZnO thin film surface polarity.

    Directory of Open Access Journals (Sweden)

    Kim Guan Saw

    Full Text Available The current-voltage characteristics of Ni contacts with the surfaces of ZnO thin films as well as single crystal (0001 ZnO substrate are investigated. The ZnO thin film shows a conversion from Ohmic to rectifying behavior when annealed at 800°C. Similar findings are also found on the Zn-polar surface of (0001 ZnO. The O-polar surface, however, only shows Ohmic behavior before and after annealing. The rectifying behavior observed on the Zn-polar and ZnO thin film surfaces is associated with the formation of nickel zinc oxide (Ni1-xZnxO, where x = 0.1, 0.2. The current-voltage characteristics suggest that a p-n junction is formed by Ni1-xZnxO (which is believed to be p-type and ZnO (which is intrinsically n-type. The rectifying behavior for the ZnO thin film as a result of annealing suggests that its surface is Zn-terminated. Current-voltage measurements could possibly be used to determine the surface polarity of ZnO thin films.

  2. Investigations of ZnO thin films deposited by a reactive pulsed laser ablation

    Institute of Scientific and Technical Information of China (English)

    Y.; C.; SOO; H.; KANDEL; M.; A.; THOMAS; C.; P.; DAGHLIAN

    2009-01-01

    Highly transparent ZnO thin films were deposited at different substrate temperatures by pulsed laser deposition in an oxygen atmosphere. The thin films were characterized by various techniques including X-ray diffraction, scanning electron microscopy, optical absorption, and photoluminescence. We demonstrated that oriented wurtzite ZnO thin films could be deposited at room temperature using a high purity zinc target. Variable temperature photoluminescence revealed new characteristics in the band edge emission. The underlying mechanism for the observed phenomena was also discussed.

  3. Nitrogen oxides and ammonia sensing characteristics of SILAR deposited ZnO thin film

    Science.gov (United States)

    Lupan, O. I.; Shishiyanu, S. T.; Shishiyanu, T. S.

    2007-07-01

    Pure and Sn, Ni doped ZnO thin films were deposited on glass substrates using a novel successive ionic layer adsorption and reaction (SILAR) method at room temperature. Microstructures of the deposited films were optimized by adjusting growth parameters. The variation in resistivity of the ZnO film sensors was performed with rapid photothermal processing (RPP). The effect of rapid photothermal processing was found to have an important role in ZnO based sensor sensitivity to NO 2, NH 3. While the undoped ZnO film surface exhibited higher NH 3 sensitivity than that of NO 2, an enhanced NO 2 sensitivity was noticed for the ZnO films doped with Sn and higher NH 3 sensitivity was obtained by Ni doping.

  4. Investigation of thin ZnO layers in view of laser desorption-ionization

    Energy Technology Data Exchange (ETDEWEB)

    Grechnikov, A A; Borodkov, A S [Vernadsky Institute of Geochemistry and Analytical Chemistry, Russian Academy of Sciences, 19 Kosygin Str., 119991 Moscow (Russian Federation); Georgieva, V B [Georgi Nadjakov Institute of Solid State Physics, Bulgarian Academy of Sciences, 72 Tzarigradsko Chaussee, 1784 Sofia (Bulgaria); Alimpiev, S S; Nikiforov, S M; Simanovsky, Ya O [General Physics Institute, Russian Academy of Sciences, 38 Vavilov Str., 119991 Moscow (Russian Federation); Dimova-Malinovska, D; Angelov, O I, E-mail: lazarova@issp.bas.b [Laboratory for Solar Energy and New Energy Sources, Bulgarian Academy of Sciences, 72 Tzarigradsko Chaussee, 1784 Sofia (Bulgaria)

    2010-04-01

    Thin zinc oxide films (ZnO) were developed as a matrix-free platform for surface assisted laser desorption-ionization (SALDI) time-of-flight mass spectrometry. The ZnO films were deposited by RF magnetron sputtering of ZnO ceramic targets in Ar atmospheres on monocrystalline silicon. The generation under UV (355 nm) laser irradiation of positive ions of atenolol, reserpine and gramicidin S from the ZnO layers deposited was studied. All analytes tested were detected as protonated molecules with no or very structure-specific fragmentation. The mass spectra obtained showed low levels of chemical background noise. All ZnO films studied exhibited high stability and good reproducibility. The detection limits for test analytes are in the 10 femtomol range.

  5. Rectifying properties of ZnO thin films deposited on FTO by electrodeposition technique

    Science.gov (United States)

    Lv, Jianguo; Sun, Yue; Zhao, Min; Cao, Li; Xu, Jiayuan; He, Gang; Zhang, Miao; Sun, Zhaoqi

    2016-03-01

    ZnO thin films were successfully grown on fluorine-doped tin oxide glass by electrodeposition technique. The crystal structure, surface morphology and optical properties of the thin films were investigated. The average crystallite size and intensity of A1(LO) mode increase with improving the absolute value of deposition potential. The best preferential orientation along c-axis and the richest oxygen interstitial defects have been observed in the sample deposited at -0.8 V. A heterojunction device consisting of ZnO thin film and n-type fluorine-doped tin oxide was fabricated. The current-voltage (I-V) characteristic of the p-n heterojunction device deposited at -0.8 V shows the best rectifying diode behavior. The p-type conductivity of the ZnO thin film could be attributed to complex defect of unintentional impurity and interstitial oxygen.

  6. Variable range hopping crossover and magnetotransport in PLD grown Sb doped ZnO thin film

    Science.gov (United States)

    Mukherjee, Joynarayan; Mannam, Ramanjaneyulu; Ramachandra Rao, M. S.

    2017-04-01

    We report on the variable range hopping (VRH) crossover in the electrical transport of Sb doped ZnO (SZO) thin film. Structural, chemical, electrical and magnetotransport properties were carried out on SZO thin film grown by pulsed laser deposition. X-photoelectron spectroscopy study confirms the presence of both Sb3+(33%) and Sb5+(67%) states. Sb doped ZnO thin film shows n-type behavior which is attributed to the formation of SbZn and/or SbZn–VZn defect complex. Temperature dependent resistivity measurement showed that in a low temperature regime (doped ZnO thin films is explained by the Khosla and Fischer model.

  7. Synthesis of Imine-Bearing ZnO Nanoparticle Thin Films and Characterization of Their Structural, Morphological and Optical Properties.

    Science.gov (United States)

    Kaur, Narinder; Sharma, Sanjeev K; Kim, Deuk Young; Sharma, Hemant; Singh, Narinder

    2015-10-01

    We are presenting the first report on the fabrication of imine-bearing ZnO nanoparticle thin films grown on Corning glass by spin coating. The sol was prepared by dissolving imine-bearing ZnO nanoparticles in dimethylsulfoxide (DMSO). The thickness of the films was manipulated to be 125-200 nm. The X-ray diffraction (XRD) analysis showed hexagonal wurtzite structure of imine-bearing ZnO nanoparticles thin films with a (002) preferential orientation. The stretching of chemical bonds of the imine linkage and Zn-O in imine-bearing ZnO nanoparticle thin films was confirmed by Fourier transform infrared spectroscopy (FTIR). The grain size of the films increased with increasing the thickness of the films due to the number of coatings and subsequently dried at 200 °C. The transmittance of imine-bearing ZnO nanoparticle thin films was observed to be ≥94%, which was in close agreement to pure ZnO thin films in the visible region. The bandgap of imine-bearing ZnO nanoparticle thin films (3.04 eV), evaluated from Tauc's plot, was observed to be lower than that of pure ZnO (3.21 eV), which is attributed to the interaction of the ZnO nanoparticles with the imine receptor.

  8. Comparative study for highly Al and Mg doped ZnO thin films elaborated by sol gel method for photovoltaic application

    Science.gov (United States)

    El Hallani, G.; Nasih, S.; Fazouan, N.; Liba, A.; Khuili, M.; Sajieddine, M.; Mabrouki, M.; Laanab, L.; Atmani, E. H.

    2017-04-01

    Transparent conducting oxides such as ZnO doped with Al or Mg are commonly used in solar cells, light emitting diodes, photodetectors, and ultraviolet laser diodes. In our work, we focus on a comparative study of the structural, optical, and electrical properties of ZnO films highly doped with Al (AZO) and Mg (MZO). These films are deposited on glass substrates by the sol-gel spin coating method. The doping concentrations for Al and Mg are fixed to 5%-30%. The XRD spectra indicate that all the samples are polycrystalline with hexagonal wurtzite structures, exhibiting a preferred orientation along the (002) plane. Low degradation in crystallinity was observed for MZO even at a Mg concentration of 30%. The MgO phase started to appear compared to Al-doped layers where smaller grains are formed inducing a deterioration in the films just after doping but no new phase appeared. This result is in agreement with other experimental results [J. K. Rath, Sol. Energy Mater. Sol. Cells 76, 431-487 (2003); Morris et al., J. Appl. Phys. 67, 1079-1087 (1990)]. By AFM analysis, the results indicate a significantly rough surface for MZO compared to AZO films. For equal Al and Mg dopant concentrations, we observe that the transmittance spectra of MZO thin films are wider than those of AZO, indicating a shift toward shorter wavelengths with an optical gap energy equal to 3.67 eV. The electrical measurements of AZO and MZO thin films were made using the I-V characteristic obtained by the four probe method. All the films present an ohmic behavior. The conductivity and the mobility of AZO films were found to be better than those of MZO.

  9. Electrical property studies on chemically processed polypyrolle/aluminum doped ZnO based hybrid heterostructures

    Science.gov (United States)

    Mohan Kumar, G.; Ilanchezhiyan, P.; Madhan Kumar, A.; Yuldashev, Sh. U.; Kang, T. W.

    2016-04-01

    A hybrid structure based on p-type polypyrolle (PPy) and n-type aluminum (Al) doped ZnO nanorods was successfully constructed. The effect of Al doping on material properties of wurtzite structured ZnO were studied using several analytical techniques. To establish the desired hybrid structure, pyrrole monomers were polymerized on hydrothermally grown Al doped ZnO nanorods by chemical polymerization. The current⿿voltage characteristics on the fabricated PPy/Al doped ZnO heterostructures were found to exhibit excellent rectifying characteristics under dark and illumination conditions. The obtained results augment the prescribed architecture to be highly suitable for high-sensitivity optoelectronic applications.

  10. Effect of chlorine doping on electrical and optical properties of ZnO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Chikoidze, E. [Groupe d' Etude de la Matiere Condensee (GEMaC), CNRS, Universite de Versailles-Saint-Quentin, 1 Place Aristide Briand. 92195 Meudon Cedex (France)], E-mail: Ekaterina.chikoidze@cnrs-bellevue.fr; Nolan, M.; Modreanu, M. [Tyndall National Institute, University College Cork, Lee Maltings, Prospect Row, Cork (Ireland); Sallet, V.; Galtier, P. [Groupe d' Etude de la Matiere Condensee (GEMaC), CNRS, Universite de Versailles-Saint-Quentin, 1 Place Aristide Briand. 92195 Meudon Cedex (France)

    2008-09-30

    Chlorine doped ZnO thin films were grown by metal-organic chemical vapour deposition (MOCVD) on sapphire and fused silica substrates. Chlorine is incorporated by substitution of oxygen and acts as a donor, leading to an increase of electron concentration. Transport properties were studied for ZnO thin films with different chlorine content. Hall effect measurements show an increase of electron carrier concentration and a decrease of electron mobility upon increasing the amount of chlorine incorporated in ZnO. The lowest resistivity {rho} = 3.6 x 10{sup -3} {omega} cm was obtained for layers deposited on sapphire substrate. UV-VIS-NIR spectroscopy has been used for the study of optical properties. For all samples, the optical transmittance in the visible range is greater than 80%. First principles computations were applied in order to examine the change in the band gap of ZnO with Cl doping.

  11. Strong adsorption of Al-doped carbon nanotubes toward cisplatin

    Science.gov (United States)

    Li, Wei; Li, Guo-Qing; Lu, Xiao-Min; Ma, Juan-Juan; Zeng, Peng-Yu; He, Qin-Yu; Wang, Yin-Zhen

    2016-08-01

    The adsorption of cisplatin molecule on Al-doped CNTs is investigated using density functional theory. The obtained results indicate that Al-doped carbon nanotubes can strongly absorb cisplatin. After absorbing cisplatin, the symmetry of CNTs has some changes. We innovatively defined a parameter of symmetry variation which relates to the adsorption. By analyzing the electronic structure, it can be concluded that under the circumstance that cisplatin was absorbed by Al-doped CNTs through aluminum atom of Al-doped CNTs. In conclusion, Al-doped CNTs is a kind of potential delivery carrier with high quality for anticancer drug cisplatin.

  12. Formation of p-type ZnO thin film through co-implantation

    Science.gov (United States)

    Chuang, Yao-Teng; Liou, Jhe-Wei; Woon, Wei-Yen

    2017-01-01

    We present a study on the formation of p-type ZnO thin film through ion implantation. Group V dopants (N, P) with different ionic radii are implanted into chemical vapor deposition grown ZnO thin film on GaN/sapphire substrates prior to thermal activation. It is found that mono-doped ZnO by N+ implantation results in n-type conductivity under thermal activation. Dual-doped ZnO film with a N:P ion implantation dose ratio of 4:1 is found to be p-type under certain thermal activation conditions. Higher p-type activation levels (1019 cm-3) under a wider thermal activation range are found for the N/P dual-doped ZnO film co-implanted by additional oxygen ions. From high resolution x-ray diffraction and x-ray photoelectron spectroscopy it is concluded that the observed p-type conductivities are a result of the promoted formation of PZn-4NO complex defects via the concurrent substitution of nitrogen at oxygen sites and phosphorus at zinc sites. The enhanced solubility and stability of acceptor defects in oxygen co-implanted dual-doped ZnO film are related to the reduction of oxygen vacancy defects at the surface. Our study demonstrates the prospect of the formation of stable p-type ZnO film through co-implantation.

  13. Growth of ZnO thin films on GaAs by pulsed laser deposition

    OpenAIRE

    Craciun, V.; Elders, J.; Gardeniers, J.G.E.; Geretovsky, J.; Boyd, Ian W.

    1995-01-01

    ZnO thin films have been grown on GaAs substrates using the pulsed laser deposition technique with or without a photodeposited SiO2 buffer layer. The presence of the SiO2 layer has a beneficial effect on the crystalline quality of the grown ZnO films. Highly c-axis oriented ZnO films having a full width at half maximum value of the (002) X-ray diffraction line of less than 0.13 ° have been grown on such buffer layers at a substrate temperature of only 350 °C.

  14. Photovoltaic Performance of Dye-Sensitized Solar Cells Based on Al-Doped TiO2 Thin Films%基于铝离子掺杂二氧化钛薄膜的染料敏化太阳能电池的光电性能

    Institute of Scientific and Technical Information of China (English)

    刘秋平; 黄慧娟; 周洋; 段彦栋; 孙庆文; 林原

    2012-01-01

    Al-doped TiO2 thin films were synthesized by the hydrothermal method.To prepare a working electrode,a TiO2 or AlTiO2 slurry was coated onto a fiuorine-doped tin oxide glass substrate by the doctor blade method and the coated substrate was sintered at 450℃.TiO2 and Al-doped TiO2 films were characterized by X-ray photoelectron spectroscopy (XPS),X-ray diffraction (XRD),scanning electron microscopy (SEM),and tested by the dye-sensitized solar cell (DSSCs) system.The influences of Al-doping on TiO2 crystal form and the photovoltaic performance of DSSCs were investigated.X-ray photoelectron spectroscopy (XPS) data indicate that the doped Al ions exist in the form of Al3+,and these ions play a role as e- or h+ traps and reduce the e-/h* pair recombination rate.The corresponding MottSchottky plot indicates that the Al-doped TiO2 photoanode shifts the fiat band potential positively.The positive shift of the fiat band potential improves the driving force of injected electrons from the LUMO of the dye to the conduction band of TiO2.The Al-doped TiO2 thin film shows a photovoltaic efficiency of 6.48%,which is higher than that of the undoped TiO2 thin film (5.58%) and the short-circuit photocurrent density increases from 16.5 to 18.2 mA·cm-2.%采用水热法制备出Al3+掺杂二氧化钛薄膜,通过玻璃棒涂于导电玻璃上,在450℃的温度下烧结并将其用N3染料敏化制成染料敏化太阳能电池(DSSCs).通过X射线光电子能谱(XPS)、X射线衍射(XRD)、扫描电镜(SEM)及DSSCs测试系统对其进行了测试表征,研究了Al3+掺杂对TiO2晶型及染料敏化太阳能电池的光电性能影响.XPS数据显示Al3+成功掺杂到了TiO2晶格内,由于Al3+的存在,对半导体内电子和空穴的捕获及阻止电子/空穴对的复合发挥重要作用.莫特-肖特基曲线显示掺杂Al3+后二氧化钛平带电位发生正移,并导致电子从染料注入到TiO2的驱动力提高.DSSCs系统测试结果表明,Al3+掺杂的TiO2

  15. Fabrication of highly transparent Al-ion-implanted ZnO thin films by metal vapor vacuum arc method

    Science.gov (United States)

    Lee, Han; Sivashanmugan, Kundan; Kao, Chi-Yuan; Liao, Jiunn-Der

    2017-03-01

    In this study, we utilized the metal vapor vacuum arc technique to implant vaporized aluminum (Al) ions in zinc oxide (ZnO) thin films. By adjusting the ion implantation dose and operational parameters, the conductivity and optical properties of the ZnO thin film can be controlled. The electrical sheet resistance of Al-ion-implanted ZnO decreased from 3.02 × 107 to 3.03 × 104 Ω/sq, while the transparency of the film was mostly preserved (91.5% at a wavelength of 550 nm). The ZnO thin-film Young’s modulus significantly increased with increasing Al ion dose.

  16. Preparation and characterization of ALD deposited ZnO thin films studied for gas sensors

    Energy Technology Data Exchange (ETDEWEB)

    Boyadjiev, S.I., E-mail: boiajiev@gmail.com [MTA-BME Technical Analytical Chemistry Research Group, Szent Gellért tér 4, Budapest, H-1111 (Hungary); Georgi Nadjakov Institute of Solid State Physics, Bulgarian Academy of Sciences, 72 Tzarigradsko Chaussee Blvd., 1784 Sofia (Bulgaria); Georgieva, V. [Georgi Nadjakov Institute of Solid State Physics, Bulgarian Academy of Sciences, 72 Tzarigradsko Chaussee Blvd., 1784 Sofia (Bulgaria); Yordanov, R. [Department of Microelectronics, Technical University of Sofia, 8 Kliment Ohridski Blvd., 1756 Sofia (Bulgaria); Raicheva, Z. [Georgi Nadjakov Institute of Solid State Physics, Bulgarian Academy of Sciences, 72 Tzarigradsko Chaussee Blvd., 1784 Sofia (Bulgaria); Szilágyi, I.M. [MTA-BME Technical Analytical Chemistry Research Group, Szent Gellért tér 4, Budapest, H-1111 (Hungary); Budapest University of Technology and Economics, Department of Inorganic and Analytical Chemistry, Szent Gellért tér 4, Budapest, H-1111 (Hungary)

    2016-11-30

    Highlights: • For the first time the gas sensing towards NO{sub 2} of very thin ALD ZnO films is studied. • The very thin ALD ZnO films showed excellent sensitivity to NO{sub 2} at room temperature. • These very thin film ZnO-based QCM sensors very well register even low concentrations. • The sensors have fully reversible sorption and are able to be recovered in short time. • Described fast and cost-effective ALD deposition of ZnO thin films for QCM gas sensor. - Abstract: Applying atomic layer deposition (ALD), very thin zinc oxide (ZnO) films were deposited on quartz resonators, and their gas sensing properties were studied using the quartz crystal microbalance (QCM) method. The gas sensing of the ZnO films to NO{sub 2} was tested in the concentration interval between 10 and 5000 ppm. On the basis of registered frequency change of the QCM, for each concentration the sorbed mass was calculated. Further characterization of the films was carried out by various techniques, i.e. by SEM-EDS, XRD, ellipsometry, and FTIR spectroscopy. Although being very thin, the films were gas sensitive to NO{sub 2} already at room temperature and could register very well as low concentrations as 100 ppm, while the sorption was fully reversible. Our results for very thin ALD ZnO films show that the described fast, simple and cost-effective technology could be implemented for producing gas sensors working at room temperature and being capable to detect in real time low concentrations of NO{sub 2}.

  17. Nonlinear optical parameters of nanocrystalline AZO thin film measured at different substrate temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Jilani, Asim, E-mail: asim.jilane@gmail.com [Centre of Nanotechnology, King Abdulaziz University, Jeddah (Saudi Arabia); Abdel-wahab, M.Sh [Centre of Nanotechnology, King Abdulaziz University, Jeddah (Saudi Arabia); Materials Science and Nanotechnology Department, Faculty of Postgraduate Studies for Advanced Sciences, Beni -Suef University, Beni-Suef (Egypt); Al-ghamdi, Attieh A. [Centre of Nanotechnology, King Abdulaziz University, Jeddah (Saudi Arabia); Dahlan, Ammar sadik [Department of architecture, faculty of environmental design, King Abdulaziz University, Jeddah (Saudi Arabia); Yahia, I.S. [Department of Physics, Faculty of Science, King Khalid University, P.O. Box 9004, Abha (Saudi Arabia); Nano-Science & Semiconductor Labs, Department of Physics, Faculty of Education, Ain Shams University, Roxy, 11757 Cairo (Egypt)

    2016-01-15

    The 2.2 wt% of aluminum (Al)-doped zinc oxide (AZO) transparent and preferential c-axis oriented thin films were prepared by using radio frequency (DC/RF) magnetron sputtering at different substrate temperature ranging from room temperature to 200 °C. For structural analysis, X-ray Diffraction (XRD) and Atomic Force Electron Microscope (AFM) was used for morphological studies. The optical parameters such as, optical energy gap, refractive index, extinction coefficient, dielectric loss, tangent loss, first and third order nonlinear optical properties of transparent films were investigated. High transmittance above 90% and highly homogeneous surface were observed in all samples. The substrate temperature plays an important role to get the best transparent conductive oxide thin films. The substrate temperature at 150 °C showed the growth of highly transparent AZO thin film. Energy gap increased with the increased in substrate temperature of Al doped thin films. Dielectric constant and loss were found to be photon energy dependent with substrate temperature. The change in substrate temperature of Al doped thin films also affect the non-liner optical properties of thin films. The value of χ{sup (3)} was found to be changed with the grain size of the thin films that directly affected by the substrate temperature of the pure and Al doped ZnO thin films.

  18. Effect of Ag Doping on Optical and Electrical Properties of ZnO Thin Films

    Institute of Scientific and Technical Information of China (English)

    XU Jin; ZHANG Zi-Yu; ZHANG Yang; LIN Bi-Xia; FU Zhu-Xi

    2005-01-01

    @@ ZnO thin films were prepared on p-type Si (100) substrates by the sol-gel process. The influence of Ag doping at a content of 0.002 % on the photoluminescence and current-voltage (Ⅰ - Ⅴ) characteristics of ZnO thin films has been investigated. It is found that Ag doping leads to a pronounced increase in the intensity of near band edge emission at 3.23 eV and a remarkable red shift of the visible broadband at room temperature. The Ⅰ - Ⅴ characteristics of ZnO/p-Si hetero junctions are also changed. These results could be explained by Ag substituting for Zn in Ag doped ZnO thin films.

  19. Ethanol Sensing Properties of Nanosheets ZnO Thin Films Prepared by Chemical Bath Deposition

    Science.gov (United States)

    Julia, Sri; Nururddin, Ahmad; Nugraha, Suyatman; Yuliarto, Brian

    2011-12-01

    Nanosheets ZnO thin films were successfully fabricated on alumina substrate by chemical bath deposition method using Zinc Nitrate Tetra hydrate as precursor. Films were annealed at 300 °C for 30 minutes and observed by X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), and Energy Dispersive X-Ray Spectroscopy (EDS) to know crystal phase and structure, surface morphology, and elemental composition respectively. The gas sensing performance of ZnO thin films was studied on exposure to ethanol gas sensing in various concentration (300 and 600 ppm). The films showed higher response towards ethanol gas sensing at optimized temperature of 250 °C and exhibited excellent sensitivity of 62.45% upon exposure 300 ppm and 69% upon exposure of 600 ppm ethanol gas sensing. Further, the response and recovery times of ZnO thin films to ethanol become shorter at higher operating temperatures. A possible mechanism of ethanol sensing has been explained.

  20. Study on pulsed laser ablation and deposition of ZnO thin films by L-MBE

    Institute of Scientific and Technical Information of China (English)

    HE YongNing; ZHANG JingWen; YANG XiaoDong; XU QingAn; ZHU ChangChun; HOU Xun

    2007-01-01

    ZnO, as a wide-band gap semiconductor, has recently become a new research focus in the field of ultraviolet optoelectronic semiconductors. Laser molecular beam epitaxy (L-MBE) is quite useful for the unit cell layer-by-layer epitaxial growth of zinc oxide thin films from the sintered ceramic target. The ZnO ceramic target with high purity was ablated by KrF laser pulses in an ultra high vacuum to deposit ZnO thin film during the process of L-MBE. It is found that the deposition rate of ZnO thin film by L-MBE is much lower than that by conventional pulsed laser deposition (PLD). Based on the experimental phenomena in the ZnO thin film growth process and the thermal-controlling mechanism of the nanosecond (ns) pulsed laser ablation of ZnO ceramic target, the suggested effective ablating time during the pulse duration can explain the very low deposition rate of the ZnO film by L-MBE. The unique dynamic mechanism for growing ZnO thin film is analyzed. Both the high energy of the deposition species and the low growth rate of the film are really beneficial for the L-MBE growth of the ZnO thin film with high crystallinity at low temperature.

  1. Annealing effect on the property of ultraviolet and green emissions of ZnO thin films

    Science.gov (United States)

    Kang, Hong Seong; Kang, Jeong Seok; Kim, Jae Won; Lee, Sang Yeol

    2004-02-01

    The mechanism of ultraviolet (UV) and green emission of ZnO thin films deposited on (001) sapphire substrates by pulsed laser deposition was investigated by using postannealing treatment at various annealing temperatures after deposition. Structural, electrical, and optical properties of ZnO films have been also observed. As the postannealing temperature increased, the intensity of UV (380 nm) peak and the carrier concentration were decreased while the intensity of the visible (about 490-530 nm) peak and the resistivity were increased. The role of oxygen in ZnO thin film during the annealing process was important to the change of optical properties. The mechanism of the luminescence suggested that UV luminescence of ZnO thin film was related to the transition from near band edge to valence band, and green luminescence of ZnO thin film was caused by the transition from deep donor level to valence band due to oxygen vacancies. The activation energy derived by using the variation of green emission intensity was 1.19 eV.

  2. EPD-deposited ZnO thin films: a review

    Energy Technology Data Exchange (ETDEWEB)

    Verde, M.

    2014-07-01

    ZnO-based materials and specifically ZnO films with tailored morphology have been subjected to extensive research in the past few years due to their high potential for multiple prospective applications, mainly in electronics. Electrophoretic Deposition (EPD) constitutes an economical, eco friendly, low energy consuming and easily scalable alternative to the high energy consuming evaporative techniques which are commonly used for the obtaining of these ZnO films. For its application, however, the use of stable, well dispersed suspensions is a necessary requirement, and thus a thorough study of their colloidal chemistry is essential. In this work the main contributions to the study of colloidal chemistry of ZnO nanoparticle suspensions and their shaping into ZnO films by EPD are summarized. (Author)

  3. Photovoltaic characteristic of Al-doped ZnO/Si heterojunction

    Energy Technology Data Exchange (ETDEWEB)

    Wang Shufang, E-mail: swang2008@hotmail.co [College of Physics Science and Technology, Hebei University, Baoding 071002 (China); Chen Mingjing; Zhao Xiaohui; Chen Jingchun; Yu Wei; Wang Jianglong [College of Physics Science and Technology, Hebei University, Baoding 071002 (China); Fu Guangsheng, E-mail: Fugs@hotmail.co [College of Physics Science and Technology, Hebei University, Baoding 071002 (China)

    2010-12-15

    A heterojunction composed of n-type Al-doped ZnO and p-type Si was fabricated and its photovoltaic properties were studied at room temperature. The heterojunction exhibits an asymmetric current-voltage relation with good rectifying characteristic. Clear photovoltaic signals are observed when the heterojunction is irradiated by the laser pulses of 308, 532 and 1064 nm, and the voltage responsivity of the 308 nm irradiation is lower than that for 532 and 1064 nm irradiations. The mechanism is proposed based on the band structure of the p-n heterojunctions. The results suggest that this Al-doped ZnO/Si heterojunction has a great potential application in the wide-band photodetectors from ultraviolet to near infrared.

  4. Effective annealing of ZnO thin films grown by three different SILAR processes

    OpenAIRE

    2015-01-01

    In the present work, zinc oxide (ZnO) thin films have been grown three different cation solution on glass substrates by a simple and economic successive ionic layer absorption and reaction method (SILAR). One of each grown different solution films was annealed to investigate to effective annealing at 473 K for 30 minutes. Absorption measurements showed that the optical band-gaps of all ZnO thin films were wide and were about 3.08-3.31 eV. All films’ band gap increased with annealing. Energy-D...

  5. Structural, optical and electronic properties of Fe doped ZnO thin films

    Science.gov (United States)

    Singh, Karmvir; Devi, Vanita; Dhar, Rakesh; Mohan, Devendra

    2015-09-01

    Fe doped ZnO thin films have been deposited by pulsed laser deposition technique on quartz substrate to study structural, optical and electronic structure using XRD, AFM, UV-visible and X-ray absorption spectroscopy. XRD study reveals that Fe doping has considerable effect on stress, strain, grain size and crystallinity of thin films. UV-visible study determines that band gap of pristine ZnO decreases with Fe doping, which can be directly correlated to transition tail width and grain size. Change in electronic structure with Fe doping has been examined by XAS study.

  6. Schottky Junction Methane Sensors Using Electrochemically Grown Nanocrystalline-Nanoporous ZnO Thin Films

    Directory of Open Access Journals (Sweden)

    P. K. Basu

    2009-01-01

    Full Text Available Nanocrystalline-nanoporous ZnO thin films were prepared by an electrochemical anodization method, and the films were tested as methane sensors. It was found that Pd-Ag catalytic contacts showed better sensing performance compared to other noble metal contacts like Pt and Rh. The methane sensing temperature could be reduced to as low as 100∘C by sensitizing nanocrystalline ZnO thin films with Pd, deposited by chemical method. The sensing mechanism has been discussed briefly.

  7. Magnetic properties of high Li doped ZnO sol–gel thin films

    Energy Technology Data Exchange (ETDEWEB)

    Vettumperumal, R. [P.G and Research Department of Physics, Sri Paramakalyani College, Alwarkurichi (India); Kalyanaraman, S., E-mail: mayura_priya2003@yahoo.co.in [P.G and Research Department of Physics, Sri Paramakalyani College, Alwarkurichi (India); Santoshkumar, B. [P.G and Research Department of Physics, Sri Paramakalyani College, Alwarkurichi (India); Thangavel, R. [Department of Physics, Indian School of Mines, Dhanbad (India)

    2014-02-01

    Highlights: • Ferromagnetism in high Li doped ZnO films. • Magnetic properties observed by Guoy's and VSM method. • The rod and wrinkle like structures are observed from the surface of the films. • Band gap of ZnO does not get altered by high Li doping. - Abstract: Undoped and Li doped ZnO thin films were deposited on a glass substrate using the sol–gel dip coating method. The films were prepared at 5 mol.% and 10 mol.% of Li doped ZnO at 550 °C annealing temperature and the deposited films were characterized by X-ray diffraction (XRD), microscopic studies, Gouy's method, vibrating sample magnetometer (VSM) and UV–visible spectroscopy. All the deposited thin films had a hexagonal wurtzite structure with polycrystalline grains at random. Primarily magnetic properties of pure and Li doped ZnO films were observed by Guoy's method which depicted Dia and Para magnetic behavior at room temperature. VSM measurement reveals a coercivity of 97.7 Oe in the films. An inverse relative ferromagnetism was perceived in Li doped ZnO films which had an average transmission of <90%.

  8. Reactive Radiofrequency Sputtering-Deposited Nanocrystalline ZnO Thin-Film Transistors

    Institute of Scientific and Technical Information of China (English)

    LI Shao-Juan; HE Xin; HAN De-Dong; SUN Lei; WANG Yi; HAN Ru-Qi; CHAN Man-Sun; ZHANG Sheng-Dong

    2012-01-01

    The structural and electrical properties of ZnO 61ms deposited by reactive radiofrequency sputtering with a metallic zinc target are systematically investigated. While the as-deposited ZnO film is in a poly-crystalline structure when the partial pressure of oxygen (pO2) is low, the grain size abruptly decreases to a few nanometers as pO2 increases to a criticaJ vaiue, and then becomes almost unchanged with a further increase in pO2.In addition, the resistivity of the ZnO films shows a non-monotonic dependence on pO2, including an abrupt transition of about seven orders of magnitude at the critical pO2. Thin-film transistors (TFTs) with the nanocrystalline ZnO films as channel layers have an on/off current ratio of more than 107, an off-current in the order of pA, a threshold voltage of about 4.5 V, and a carrier mobility of about 2cm2/(V-s). The results show that radiofrequency sputtered ZnO with a zinc target is a promising candidate for high-performance ZnO TFTs.%The structural and electrical properties of ZnO films deposited by reactive radiofrequency sputtering with a metallic zinc target are systematically investigated.While the as-deposited ZnO film is in a poly-crystalline structure when the partial pressure of oxygen (pO2 ) is low,the grain size abruptly decreases to a few nanometers as pO2 increases to a critical value,and then becomes almost unchanged with a further increase in pO2.In addition,the resistivity of the ZnO films shows a non-monotonic dependence on pO2,including an abrupt transition of about seven orders of magnitude at the critical pO2.Thin-film transistors (TFTs) with the nanocrystalline ZnO films as channel layers have an on/off current ratio of more than 10 7,an off-current in the order of pA,a threshold voltage of about 4.5 V,and a carrier mobility of about 2 cm2/(V.s).The results show that radiofrequency sputtered ZnO with a zinc target is a promising candidate for high-performance ZnO TFTs.

  9. Percentage of different aluminum doping influence the morphological and optical properties of ZnO nanostructured growth for sensor application

    Energy Technology Data Exchange (ETDEWEB)

    Mohamed, R., E-mail: ruziana12@gmail.com [NANO-ElecTronic Centre, Faculty of Electrical engineering, Universiti Teknologi MARA, 40450 Shah Alam, Selangor (Malaysia); NANO-SciTech Centre, Institue of Science, Universiti Teknologi MARA, 40450 Shah Alam, Selangor (Malaysia); Faculty of Applied Sciences, Universiti Teknologi MARA Pahang, 26400 Bandar Tun Razak Jengka, Pahang (Malaysia); Ismail, A. S., E-mail: kyrin-samaxi@yahoo.com [NANO-ElecTronic Centre, Faculty of Electrical engineering, Universiti Teknologi MARA, 40450 Shah Alam, Selangor (Malaysia); Khusaimi, Z., E-mail: Zurai142@salam.uitm.edu.my [NANO-SciTech Centre, Institue of Science, Universiti Teknologi MARA, 40450 Shah Alam, Selangor (Malaysia); Faculty of Applied Sciences, Universiti Teknologi MARA, 40450 Shah Alam, Selangor (Malaysia); Mamat, M. H., E-mail: hafiz-030@yahoo.com [NANO-ElecTronic Centre, Faculty of Electrical engineering, Universiti Teknologi MARA, 40450 Shah Alam, Selangor (Malaysia); NANO-SciTech Centre, Institue of Science, Universiti Teknologi MARA, 40450 Shah Alam, Selangor (Malaysia); Alrokayan, Salman A. H., E-mail: dr.salman@alrokayan.com; Khan, Haseeb A., E-mail: khan-haseeb@yahoo.com [Department of Biochemistry, College of Science, King Saud University (KSU), Riyadh 11451 (Saudi Arabia); Rusop, M., E-mail: nanouitm@gmail.com [NANO-SciTech Centre, Institue of Science, Universiti Teknologi MARA, 40450 Shah Alam, Selangor (Malaysia); Faculty of Applied Sciences, Universiti Teknologi MARA Pahang, 26400 Bandar Tun Razak Jengka, Pahang (Malaysia)

    2016-07-06

    In this work, Zinc Oxide (ZnO) with different aluminum (Al) doping percentage was synthesis by sol gel immersion method. Al doped ZnO at various doping percentage from 1, 2, 3, 4 and 5. It was found that with different Al percentage influence the morphological and optical properties of ZnO growth. Field Emission Scanning Electron Microscope (FESEM) image showed the use of different Al doping causes the difference in geometry and size of ZnO nanorods growth. Based on UV-Vis spectroscopy, the transmittance at 1% Al doping has the highest spectrum.

  10. Characteristics of THz carrier dynamics in GaN thin film and ZnO nanowires by temperature dependent terahertz time domain spectroscopy measurement

    Science.gov (United States)

    Balci, Soner; Baughman, William; Wilbert, David S.; Shen, Gang; Kung, Patrick; Kim, Seongsin Margaret

    2012-12-01

    We present a comprehensive study of the characteristics of carrier dynamics using temperature dependent terahertz time domain spectroscopy. By utilizing this technique in combination with numerical calculations, the complex refractive index, dielectric function, and conductivity of n-GaN, undoped ZnO NWs, and Al-doped ZnO NWs were obtained. The unique temperature dependent behaviors of major material parameters were studied at THz frequencies, including plasma frequency, relaxation time, carrier concentration and mobility. Frequency and temperature dependent carrier dynamics were subsequently analyzed in these materials through the use of the Drude and the Drude-Smith models.

  11. Random lasing of ZnO thin films grown by pulsed-laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Cachoncinlle, C., E-mail: christophe.cachoncinlle@univ-orleans.fr [GREMI, UMR 7344 CNRS—Université Orléans, 45067 Orléans Cedex 2 (France); Hebert, C.; Perrière, J. [Sorbonne Universités, UPMC Université Paris 06, UMR 7588, INSP, 75005 Paris (France); CNRS, UMR 7588, INSP, 75005 Paris (France); Nistor, M. [NILPRP, L 22 PO Box. MG-36, 77125 Bucharest—Magurele (Romania); Petit, A.; Millon, E. [GREMI, UMR 7344 CNRS—Université Orléans, 45067 Orléans Cedex 2 (France)

    2015-05-01

    Highlights: • Random lasing at RT in nanocrystalline ZnO PLD thin film (<100 nm). • Low optical pumping threshold (<30 kW cm{sup −2}) for UV random lasing. • Random lasing interpreted by the electron-hole plasma (EHP) model. - Abstract: Low-dimensional semiconductor structures on nanometer scale are of great interest because of their strong potential applications in nanotechnologies. We report here optical and structural properties on UV lasing in ZnO thin films. The ZnO films, 110 nm thick, were prepared using pulsed-laser deposition on c-cut sapphire substrates at 500 °C under 10{sup −2} oxygen pressure. The ZnO films are nearly stoichiometric, dense and display the wurtzite phase. The films are highly textured along the ZnO c-axis and are constituted of nanocrystallites. According to Hall measurements these films are conductive (0.11 Ω cm). Photoluminescence measurements reveals a so-called random lasing in the range 390 to 410 nm, when illuminating at 355 nm with a tripled frequency pulsed Nd-YAG laser. Such random lasing is obtained at rather low optical pumping, 45 kW cm{sup −2}, a value lower than those classically reported for pulsed-laser deposition thin films.

  12. Nanoscale heterogeniety and workfunction variations in ZnO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Anirudh [Flinders Centre for NanoScale Science and Technology, Flinders University, PO Box 2100, Adelaide 5001, SA (Australia); Max Planck Institute for Polymer Research, Ackermannweg 10, Mainz 55128 (Germany); Untch, Maria [Max Planck Institute for Polymer Research, Ackermannweg 10, Mainz 55128 (Germany); Quinton, Jamie S. [Flinders Centre for NanoScale Science and Technology, Flinders University, PO Box 2100, Adelaide 5001, SA (Australia); Berger, Rüdiger, E-mail: berger@mpip-mainz.mpg.de [Max Planck Institute for Polymer Research, Ackermannweg 10, Mainz 55128 (Germany); Andersson, Gunther; Lewis, David A. [Flinders Centre for NanoScale Science and Technology, Flinders University, PO Box 2100, Adelaide 5001, SA (Australia)

    2016-02-15

    Graphical abstract: - Highlights: • Quantitative insight in lateral work function distribution was obtained. • Ramp-annealed ZnO exhibits two electronically distinct nanoscale regions. • Comparative UPS and KPFM studies were performed to measure work function of heterogeneous surface. - Abstract: Nano-roughened, sol–gel derived polycrystalline ZnO thin films prepared by a thermal ramping procedure were found to exhibit different work function values on a sub-micrometer scale. By Kelvin probe force microscopy (KPFM) two distinct nanoscale regions with work function differing by over 0.1 eV were detected which did not coincide with the nano-roughened surface topography. In contrast, a flat ZnO surface displayed a single, uniform distribution. Ultraviolet photoelectron spectroscopy (UPS) studies showed that the average workfunction across a flat ZnO surface was 3.7 eV while ZnO with a nano-roughened morphology had a lower workfunction of 3.4 eV with indications of electronic heterogeneity across the surface, supporting the KPFM results. Scanning Auger Nanoprobe measurements showed that the chemical composition was uniform across the surface in all samples, suggesting the work function heterogeneity was due to variations in crystallinity or crystal orientation on the surface of these thin films. Such heterogeneity in the electronic properties of materials in thin film devices can significantly influence the interfacial charge transport across materials.

  13. Structural and morphological study of ZnO thin films electrodeposited on n-type silicon

    Energy Technology Data Exchange (ETDEWEB)

    Ait Ahmed, N., E-mail: nadiaitahmed@yahoo.fr [Laboratoire de Technologie des materiaux et Genie des Procedes : Equipe d' electrochimie - Corrosion Universite Abderrahmane Mira, Bejaia, 06000 (Algeria); Unite de Developpement de la Technologie du Silicium, 02 Bd Frantz Fanon, B.P. 140, Alger 7 Merveilles (Algeria); Fortas, G. [Unite de Developpement de la Technologie du Silicium, 02 Bd Frantz Fanon, B.P. 140, Alger 7 Merveilles (Algeria); Hammache, H. [Laboratoire de Technologie des materiaux et Genie des Procedes : Equipe d' electrochimie - Corrosion Universite Abderrahmane Mira, Bejaia, 06000 (Algeria); Sam, S.; Keffous, A.; Manseri, A. [Unite de Developpement de la Technologie du Silicium, 02 Bd Frantz Fanon, B.P. 140, Alger 7 Merveilles (Algeria); Guerbous, L. [Centre de Recherche Nucleaire d' Alger (Algeria); Gabouze, N., E-mail: ngabouze@yahoo.fr [Unite de Developpement de la Technologie du Silicium, 02 Bd Frantz Fanon, B.P. 140, Alger 7 Merveilles (Algeria)

    2010-10-01

    In this work, we report on the electrodeposition of ZnO thin films on n-Si (1 0 0) and glass substrates. The influence of the deposition time on the morphology of ZnO thin films was investigated. The ZnO thin films were characterized by X-ray diffraction (XRD), energy dispersive X-ray (EDS) and scanning electron microscopy (SEM). The results show a variation of ZnO texture from main (0 0 2) at 10 min to totally (1 0 1) at 15 min deposition time. The photoluminescence (PL) studies show that both UV ({approx}382 nm) and blue ({approx}432 nm) luminescences are the main emissions for the electrodeposited ZnO films. In addition, the film grown at 15 min indicates an evident decrease of the yellow-green ({approx}520 nm) emission band comparing with that of 10 min. Finally, transmittance spectra show a high transmission value up to 85% in the visible wavelength range. Such results would be very interesting for solar cells applications.

  14. Preparation and properties of ZnO thin films deposited by sol-gel technique

    Institute of Scientific and Technical Information of China (English)

    LAN Wei; PENG Xingping; LIU Xueqin; HE Zhiwei; WANG Yinyue

    2007-01-01

    Zinc oxide (ZnO) thin films were deposited on (100) Si substrates by sol-gel technique.Zinc acetate was used as the precursor material.The effect of different anneal-ing atmospheres and annealing temperatures on composition, structural and optical properties of ZnO thin films was inves-tigated by using Fourier transform infrared spectroscopy, X-ray diffraction,atomic force microscopy and photolumi-nescence (PL),respectively.At an annealing temperature of 400℃ in N2 for 2 h,dried gel films were propitious to undergo structural relaxation and grow ZnO grains.ZnO thin film annealed at 400℃ in N2 for 2 h exhibited the optimal structure and PL property,and the grain size and the lattice constants of the film were calculated (41.6 nm,a = 3.253 A and c=5.210A).Moreover,a green emission around 495 nm was observed in the PL spectra owing to the oxygen vacancies located at the surface of ZnO grains.With increas- ing annealing temperature,both the amount of the grown ZnO and the specific surface area of the grains decrease,which jointly weaken the green emission.

  15. Gallium doping in transparent conductive ZnO thin films prepared by chemical spray pyrolysis

    Science.gov (United States)

    Babar, A. R.; Deshamukh, P. R.; Deokate, R. J.; Haranath, D.; Bhosale, C. H.; Rajpure, K. Y.

    2008-07-01

    Zinc oxide (ZnO) and ZnO : Ga films have been deposited by the spray pyrolysis method onto preheated glass substrates using zinc acetate and gallium nitrate as precursors for Zn and Ga ions, respectively. The effect of Ga doping on the structural, morphological, optical and electrical properties of sprayed ZnO thin films were investigated using x-ray diffraction (XRD), scanning electron microscopy, optical absorption, photoluminescence (PL) and Hall effect techniques. XRD studies reveal that films are polycrystalline with hexagonal (wurtzite) crystal structure. The thin films were oriented along the (0 0 2) plane. Room temperature PL measurements indicate that the deposited films exhibit proper doping of Ga in ZnO lattice. The average transparency in the visible range was around ~85-95% for typical thin film deposited using 2 at% gallium doping. The optical band gap increased from 3.31 to 3.34 eV with Ga doping of 2 at%. The addition of gallium induces a decrease in electrical resistivity of the ZnO : Ga films up to 2 at% gallium doping. The highest figure of merit observed in this present study was 3.09 × 10-3 cm2 Ω-1.

  16. Gallium doping in transparent conductive ZnO thin films prepared by chemical spray pyrolysis

    Energy Technology Data Exchange (ETDEWEB)

    Babar, A R; Deshamukh, P R; Deokate, R J; Bhosale, C H; Rajpure, K Y [Electrochemical Materials Laboratory, Department of Physics, Shivaji University, Kolhapur 416 004 (India); Haranath, D [National Physical Laboratory, Dr K S Krishnan Road, New Delhi 110 012 (India)], E-mail: rajpure@yahoo.com

    2008-07-07

    Zinc oxide (ZnO) and ZnO : Ga films have been deposited by the spray pyrolysis method onto preheated glass substrates using zinc acetate and gallium nitrate as precursors for Zn and Ga ions, respectively. The effect of Ga doping on the structural, morphological, optical and electrical properties of sprayed ZnO thin films were investigated using x-ray diffraction (XRD), scanning electron microscopy, optical absorption, photoluminescence (PL) and Hall effect techniques. XRD studies reveal that films are polycrystalline with hexagonal (wurtzite) crystal structure. The thin films were oriented along the (0 0 2) plane. Room temperature PL measurements indicate that the deposited films exhibit proper doping of Ga in ZnO lattice. The average transparency in the visible range was around {approx}85-95% for typical thin film deposited using 2 at% gallium doping. The optical band gap increased from 3.31 to 3.34 eV with Ga doping of 2 at%. The addition of gallium induces a decrease in electrical resistivity of the ZnO : Ga films up to 2 at% gallium doping. The highest figure of merit observed in this present study was 3.09 x 10{sup -3} cm{sup 2} {omega}{sup -1}.

  17. DFT calculations on electronic properties of ZnO thin films deposited by spray pyrolysis

    Energy Technology Data Exchange (ETDEWEB)

    Cordeiro, J.M.; Reynoso, V.C.; Azevedo, D.H.M. [Universidade Estadual Paulista Julio de Mesquita Filho (UNESP), SP (Brazil)

    2016-07-01

    Full text: Introduction - Thin films of Zinc oxide (ZnO) has a wide range of technological applications, as transparent conducting electrodes in solar cells, flat panel displays, and sensors, for example. More recently applications in optoelectronics, like light emitter diodes and laser diodes, due to its large band gap, are been explored. Studies of ZnO thin films are important for these applications. Methodology - In this study thin films of ZnO have been deposited by spray pyrolysis on glass substrate. The films were characterized by XRD and UV-VIS techniques and the electronic properties as a function of the film thickness have been investigated by DFT calculations with B3LYP hybrid potential implemented in the CRYSTAL09 code. Results - The diffractograms obtained for the ZnO thin films as a function of the thickness are shown. The films exhibit a hexagonal wurtzite structure with preferred c-axis orientation in (002) direction of ZnO crystal. A quantum mechanical approach based on the periodic Density Functional Theory (DFT), with B3LYP hybrid potential was used to investigate the electronic structure of the films as a function of the thickness. The CRYSTAL09 code has been used for the calculations on the wurtzite hexagonal structure of ZnO - spatial group P63mc. For optimizing the geometry of the pure ZnO crystal, the experimental lattice parameters were got as follows: a= 0.325 nm, b= 0.325 nm, c= 0.5207 nm with c/a= 1.602. Considering to the calculations of the band structure, it is suggested that the semiconducting properties of ZnO arises from the overlapping of the 4s orbital of the conducting band of Zn and the 2p orbital of the top of valence band of O. Conclusions - The structure of ZnO thin film deposited on glass substrate present preferential orientation in (002) direction. Variation in the optical properties as a function of the film thickness was observed. The band gap energy was determined from optical analysis to be ∼ 3.27 eV. The refractive

  18. Synthesis, structural and optical characterization of undoped, N-doped ZnO and co-doped ZnO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Pathak, Trilok Kumar, E-mail: tpathak01@gmail.com; Kumar, R.; Purohit, L. P., E-mail: proflppurohitphys@gmail.com [Semiconductor Research Lab., Department of Physics, Gurukula Kangri University, Haridwar (India)

    2015-05-15

    ZnO, N-doped ZnO and Al-N co-doped ZnO thin films were deposited on ITO coated corning glass by spin coater using sol-gel method. The films were annealed in air at 450°C for one hour. The crystallographic structure and morphology of the films were studied by X-ray diffraction (XRD) and scanning electron microscopy (SEM) respectively. The X-ray diffraction results confirm that the thin films are of wurtzite hexagonal with a very small distortion. The optical properties were investigated by transmission spectra of different films using spectrophotometer (Shimadzu UV-VIS-NIR 3600). The results indicate that the N doped ZnO thin films have obviously enhanced transmittance in visible region. Moreover, the thickness of the films has strong influences on the optical constants.

  19. Study on pulsed laser ablation and deposition of ZnO thin films by L-MBE

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    ZnO,as a wide-band gap semiconductor,has recently become a new research fo-cus in the field of ultraviolet optoelectronic semiconductors. Laser molecular beam epitaxy(L-MBE) is quite useful for the unit cell layer-by-layer epitaxial growth of zinc oxide thin films from the sintered ceramic target. The ZnO ceramic target with high purity was ablated by KrF laser pulses in an ultra high vacuum to deposit ZnO thin film during the process of L-MBE. It is found that the deposition rate of ZnO thin film by L-MBE is much lower than that by conventional pulsed laser deposition(PLD) . Based on the experimental phenomena in the ZnO thin film growth process and the thermal-controlling mechanism of the nanosecond(ns) pulsed laser abla-tion of ZnO ceramic target,the suggested effective ablating time during the pulse duration can explain the very low deposition rate of the ZnO film by L-MBE. The unique dynamic mechanism for growing ZnO thin film is analyzed. Both the high energy of the deposition species and the low growth rate of the film are really beneficial for the L-MBE growth of the ZnO thin film with high crystallinity at low temperature.

  20. Development of Solution-Processed ZnO Nanorod Arrays Based Photodetectors and the Improvement of UV Photoresponse via AZO Seed Layers.

    Science.gov (United States)

    Zhang, Yuzhu; Xu, Jianping; Shi, Shaobo; Gao, Yanyan; Wang, Chang; Zhang, Xiaosong; Yin, Shougen; Li, Lan

    2016-08-31

    Designing a rational structure and developing an efficient fabrication technique for bottom-up devices offer a promising opportunity for achieving high-performance devices. In this work, we studied how Al-doped ZnO (AZO) seed layer films influence the morphology and optical and electrical properties for ZnO aligned nanorod arrays (NRs) and then the performance of ZnO NRs based ultraviolet photodetectors (UV PDs) with Au/ZnO NRs Schottky junctions and p-CuSCN/n-ZnO NRs heterojunctions. The PD with AZO thin film with 0.5 at. % Al doping (named as AZO (0.5%)) exhibited more excellent photoresponse properties than that with pristine ZnO and AZO (1%) thin films. This phenomenon can be ascribed to the good light transmission of the AZO layer, increased density of the NRs, and improved crystallinity of ZnO NRs. The PDs based on CuSCN/ZnO NRs heterojunctions showed good rectification characteristics in the dark and self-powered UV photoresponse properties with excellent stability and reproducibility under low-intensity illumination conditions. A large responsivity located at 365 nm of 22.5 mA/W was achieved for the PD with AZO (0.5%) thin film without applied bias. The internal electric field originated from p-CuSCN/n-ZnO NRs heterojunctions can separate photogenerated carriers in ZnO NRs and drift toward the corresponding electrode.

  1. Structural characterization of supported nanocrystalline ZnO thin films prepared by dip-coating

    Energy Technology Data Exchange (ETDEWEB)

    Casanova, J.R. [CITEDEF-CINSO-CONICET Centro de Investigaciones en Solidos, Juan B. de La Salle 4397, B1603ALO, Villa Martelli, Buenos Aires (Argentina); Heredia, E.A., E-mail: eheredia@citedef.gob.ar [CITEDEF-CINSO-CONICET Centro de Investigaciones en Solidos, Juan B. de La Salle 4397, B1603ALO, Villa Martelli, Buenos Aires (Argentina); Bojorge, C.D.; Canepa, H.R. [CITEDEF-CINSO-CONICET Centro de Investigaciones en Solidos, Juan B. de La Salle 4397, B1603ALO, Villa Martelli, Buenos Aires (Argentina); Kellermann, G. [Departamento de Fisica, Universidade Federal do Parana, Curitiba, PR (Brazil); Craievich, A.F. [Instituto de Fisica, Universidade de Sao Paulo, Cidade Universitaria, Sao Paulo, SP (Brazil)

    2011-09-15

    Nanocrystalline ZnO thin films prepared by the sol-gel dip-coating technique were characterized by grazing incidence X-ray diffraction (GIXD), atomic force microscopy (AFM), X-ray reflectivity (XR) and grazing incidence small-angle X-ray scattering (GISAXS). The structures of several thin films subjected to (i) isochronous annealing at 350, 450 and 550 deg. C, and (ii) isothermal annealing at 450 deg. C during different time periods, were characterized. The studied thin films are composed of ZnO nanocrystals as revealed by analysing several GIXD patterns, from which their average sizes were determined. Thin film thickness and roughness were determined from quantitative analyses of AFM images and XR patterns. The analysis of XR patterns also yielded the average density of the studied films. Our GISAXS study indicates that the studied ZnO thin films contain nanopores with an ellipsoidal shape, and flattened along the direction normal to the substrate surface. The thin film annealed at the highest temperature, T = 550 deg. C, exhibits higher density and lower thickness and nanoporosity volume fraction, than those annealed at 350 and 450 deg. C. These results indicate that thermal annealing at the highest temperature (550 deg. C) induces a noticeable compaction effect on the structure of the studied thin films.

  2. Synthesis and Characterization of Molybdenum Doped ZnO Thin Films by SILAR Deposition Method

    Science.gov (United States)

    Radha, R.; Sakthivelu, A.; Pradhabhan, D.

    2016-08-01

    Molybdenum (Mo) doped zinc oxide (ZnO) thin films were deposited on the glass substrate by Successive Ionic Layer Adsorption and Reaction (SILAR) deposition method. The effect of Mo dopant concentration of 5, 6.6 and 10 mol% on the structural, morphological, optical and electrical properties of n-type Mo doped ZnO films was studied. The X-ray diffraction (XRD) results confirmed that the Mo doped ZnO thin films were polycrystalline with wurtzite structure. The field emission scanning electron microscopy (FESEM) studies shows that the surface morphology of the films changes with Mo doping. A blue shift of the optical band gap was observed in the optical studies. Effect of Mo dopant concentration on electrical conductivity was studied and it shows comparatively high electrical conductivity at 10 mol% of Mo doping concentration.

  3. Physical properties of ZnO thin films deposited at various substrate temperatures using spray pyrolysis

    Energy Technology Data Exchange (ETDEWEB)

    Prasada Rao, T., E-mail: prasadview@gmail.co [Advanced Materials Laboratory, Department of Physics, National Institute of Technology, Tiruchirappalli-620015 (India); Santhosh Kumar, M.C., E-mail: santhoshmc@yahoo.co [Advanced Materials Laboratory, Department of Physics, National Institute of Technology, Tiruchirappalli-620015 (India); Safarulla, A. [Advanced Materials Laboratory, Department of Physics, National Institute of Technology, Tiruchirappalli-620015 (India); Ganesan, V.; Barman, S.R. [UGC-DAE Consortium for Scientific Research, Indore-452001 (India); Sanjeeviraja, C. [School of Physics, Alagappa University, Karaikudi-630003 (India)

    2010-05-01

    Zinc oxide (ZnO) thin films have been deposited with various substrate temperatures by spray pyrolysis technique onto glass substrates. X-ray diffraction (XRD) results showed the random growth orientation of the crystallites and the presence of the wurtzite phase of ZnO. The x-ray photoelectron spectroscopy (XPS) measurements reveal the presence of Zn{sup 2+} and chemisorbed oxygen in ZnO thin films. Atomic force micrograms (AFM) revealed a granular, polycrystalline morphology for the films. The grain size is found to increase as the substrate temperature increases. All films exhibit a transmittance of about 85% in the visible region. The photoluminescence (PL) measurements indicated that the intensity of emission peaks significantly varying with substrate temperature. Electrical resistivity has been found to decrease; while the carrier concentration increases with substrate temperature.

  4. Influence of Bi doping on the electrical and optical properties of ZnO thin films

    Science.gov (United States)

    Abed, S.; Bougharraf, H.; Bouchouit, K.; Sofiani, Z.; Derkowska-Zielinska, B.; Aida, M. S.; Sahraoui, B.

    2015-09-01

    Transparent conducting ZnO doped Bi thin films were prepared on glass substrates by ultrasonic spray method. The influence of Bi doping concentration on the structural, optical and nonlinear optical properties of ZnO thin films was studied. The X-ray diffraction (XRD) analysis show that all studied films have a hexagonal wurtzite structure and are preferentially oriented along the c-axis from substrate surface. Optical transmittance measurements show that all samples have average 80% transparency in the visible light. Optical band gap values range between 3.14 and 3.28 eV. ZnO film with 3 wt% of Bi showed the highest electrical conductivity. In addition, the second and third order nonlinear susceptibilities were determined and their values have been calculated.

  5. Nanostructured ZnO thin films prepared by sol–gel spin-coating

    Energy Technology Data Exchange (ETDEWEB)

    Heredia, E., E-mail: heredia.edu@gmail.com [UNIDEF (CONICET-MINDEF), J.B. de La Salle 4397, 1603 Villa Martelli, Pcia. de Buenos Aires (Argentina); Bojorge, C.; Casanova, J.; Cánepa, H. [UNIDEF (CONICET-MINDEF), J.B. de La Salle 4397, 1603 Villa Martelli, Pcia. de Buenos Aires (Argentina); Craievich, A. [Instituto de Física, Universidade de São Paulo, Cidade Universitária, 66318 São Paulo, SP (Brazil); Kellermann, G. [Universidade Federal do Paraná, 19044 Paraná (Brazil)

    2014-10-30

    Highlights: • ZnO films synthesized by sol–gel were deposited by spin-coating on flat substrates. • Structural features of ZnO films with several thicknesses were characterized by means of different techniques. • The thicknesses of different ZnO thin films were determined by means of FESEM and AFM. • The nanoporous structures of ZnO thin films were characterized by GISAXS using IsGISAXS software. • The average densities of ZnO thin films were derived from (i) the critical angle in 1D XR patterns, (ii) the angle of Yoneda peak in 2D GISAXS images, (iii) minimization of chi2 using IsGISAXS best fitting procedure. - Abstract: ZnO thin films deposited on silica flat plates were prepared by spin-coating and studied by applying several techniques for structural characterization. The films were prepared by depositing different numbers of layers, each deposition being followed by a thermal treatment at 200 °C to dry and consolidate the successive layers. After depositing all layers, a final thermal treatment at 450 °C during 3 h was also applied in order to eliminate organic components and to promote the crystallization of the thin films. The total thickness of the multilayered films – ranging from 40 nm up to 150 nm – was determined by AFM and FESEM. The analysis by GIXD showed that the thin films are composed of ZnO crystallites with an average diameter of 25 nm circa. XR results demonstrated that the thin films also exhibit a large volume fraction of nanoporosity, typically 30–40 vol.% in thin films having thicknesses larger than ∼70 nm. GISAXS measurements showed that the experimental scattering intensity is well described by a structural model composed of nanopores with shape of oblate spheroids, height/diameter aspect ratio within the 0.8–0.9 range and average diameter along the sample surface plane in the 5–7 nm range.

  6. CdS quantum dots sensitized Cu doped ZnO nanostructured thin films for solar cell applications

    Science.gov (United States)

    Poornima, K.; Gopala Krishnan, K.; Lalitha, B.; Raja, M.

    2015-07-01

    ZnO nanorods and Cu doped ZnO nanorods thin films have been prepared by simple hydrothermal method. CdS quantum dots are sensitized with Cu doped ZnO nanorod thin films using successive ionic layer adsorption and reaction (SILAR) method. The X-ray diffraction study reveals that ZnO nanorods, and CdS quantum dot sensitized Cu doped ZnO nanorods exhibit hexagonal structure. The scanning electron microscope image shows the presence of ZnO nanorods. The average diameter and length of the aligned nanorod is 300 nm and 1.5 μm respectively. The absorption spectra shows that the absorption edge of CdS quantum dot sensitized ZnO nanorod thin film is shifted toward longer wavelength region when compared to the absorption edge of ZnO nanorods film. The conversion efficiency of the CdS quantum dot sensitized Cu doped ZnO nanorod thin film solar cell is 1.5%.

  7. Carrier dynamics and gain spectra at room-temperature in epitaxial ZNO thin films

    DEFF Research Database (Denmark)

    Yu, Ping; Hvam, Jørn Märcher; Wong, K. S.

    1999-01-01

    Carrier dynamics of epitaxial ZnO thin film was investigated using a frequency up-conversion tehcnique. At lower carrier densities, the decay time of free exciton recombination was measured to be 24 ps. Rapid decay times of a few picoseconds were observed at higher carrier densities, which show a...

  8. Room temperature ferromagnetism in Cd-doped ZnO thin films through defect engineering

    Energy Technology Data Exchange (ETDEWEB)

    Debbichi, M., E-mail: mourad_fsm@yahoo.fr [Laboratoire de la matière condensée et nanosciences, Département de Physique, Faculté des Sciences de Monastir, 5019 Monastir (Tunisia); Souissi, M. [College of Arts and Science Nayriya, Dammam University, 31441 Dammam (Saudi Arabia); Fouzri, A. [Laboratoire Physico-Chimie des Matériaux, Unité de Service Commun de Recherche ‘‘High Resolution X-ray Diffractometer’’, Département de Physique, Université de Monastir, Faculté des Sciences de Monastir, Avenue de l’Environnement, 5019 Monastir (Tunisia); Schmerber, G. [Institut de Physique et Chimie des Matériaux de Strasbourg (IPCMS) UMR 7504 CNRS-Université de Strasbourg, 23 rue du Loess, BP 43, 67034 Strasbourg Cedex 2 (France); Said, M. [Laboratoire de la matière condensée et nanosciences, Département de Physique, Faculté des Sciences de Monastir, 5019 Monastir (Tunisia); Alouani, M. [Institut de Physique et Chimie des Matériaux de Strasbourg (IPCMS) UMR 7504 CNRS-Université de Strasbourg, 23 rue du Loess, BP 43, 67034 Strasbourg Cedex 2 (France)

    2014-06-15

    Highlights: • ZnO:Cd thin film grown on c-sapphire substrate by MOCVD method. • RTFM in ZnO:Cd thin film is detected by SQUID magnetometer measurement. • DFT theory is conducted to elucidate the mechanism of RTFM in Cd-doped ZnO. - Abstract: Room-temperature ferromagnetism is detected in undoped and cadmium-doped ZnO (ZnO:Cd) thin film grown on c-plane sapphire substrate by metal–organic chemical vapor deposition method. To elucidate the origin of ferromagnetism, a theoretical study based on density functional theory is conducted, focusing on the role of the neutral cation vacancy on the appearance of magnetism in Cd-doped ZnO thin film. The calculations revealed that Cd substitution at Zn sites contributes to the long-ranged ferromagnetism in ZnO by lowering the formation energy of Zn vacancies and thereby stabilizing Zn vacancies from which the magnetic moments originate.

  9. Development of novel control system to grow ZnO thin films by reactive evaporation

    Directory of Open Access Journals (Sweden)

    Gerardo Gordillo

    2016-07-01

    Full Text Available This work describes a novel system implemented to grow ZnO thin films by plasma assisted reactive evaporation with adequate properties to be used in the fabrication of photovoltaic devices with different architectures. The innovative aspect includes both an improved design of the reactor used to activate the chemical reaction that leads to the formation of the ZnO compound as an electronic system developed using the virtual instrumentation concept. ZnO thin films with excellent opto-electrical properties were prepared in a reproducible way, controlling the deposition system through a virtual instrument (VI with facilities to control the amount of evaporated zinc involved in the process that gives rise to the formation of ZnO, by means of the incorporation of PID (proportional integral differential and PWM (pulse width modulation control algorithms. The effectiveness and reliability of the developed system was verified by obtaining with good reproducibility thin films of n+-ZnO and i-ZnO grown sequentially in situ with thicknesses and resistivities suitable for use as window layers in chalcopyrite based thin film solar cells.

  10. Sputter deposition of ZnO thin films at high substrate temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Kronenberger, Achim; Eisermann, Sebastian; Laufer, Andreas; Graubner, Swen; Polity, Angelika; Meyer, Bruno K. [I. Physikalisches Institut, Justus-Liebig-Universitaet Giessen (Germany)

    2008-07-01

    For the use of sputter deposited ZnO thin films in semiconductor devices, not only the electrical behaviour but also to maintain high crystal quality of the deposited films is important. Pure ZnO thin films have been prepared on quartz glass and sapphire substrates by radio-frequency (RF) sputtering using a ceramic ZnO target. The substrate-temperature during the deposition could be adjusted from RT up to 735 C. Argon was used as sputter-gas and oxygen as reactive-gas to change the stoichiometry of the deposited thin films. The crystallinity of the deposited films has been analysed by XRD measurements. For optical and electrical characterisation optical transmission and Hall-effect measurements have been performed. To investigate impurities the films have been analysed by EDX and SIMS. The focus was set on the electrical and optical properties of the deposited ZnO thin films and their changing behaviour in the cause of the different deposition parameters such as gas pressures, substrate temperature and rf-power. The aim was to gain control over changing the resistivity in a wide range, while keeping the films transparent in the visible region of the electromagnetic spectra and simultaneous maintain a high crystal quality.

  11. Photoelectrocatalytic degradation of phthalic acid using spray deposited stratified WO3/ZnO thin films under sunlight illumination

    Science.gov (United States)

    Hunge, Y. M.; Mahadik, M. A.; Moholkar, A. V.; Bhosale, C. H.

    2017-10-01

    In the present work, stratified WO3/ZnO thin films have been prepared by simple chemical spray pyrolysis technique. The structural, morphological, compositional and photoelectrocatalytic properties of the stratified WO3/ZnO thin films are studied. The photoelectrochemical (PEC) study shows that, both short circuit current (Isc) and open circuit voltage (Voc) are (Isc = 1.023 mA and Voc = 0.980 V) relatively high at 40 ml spraying quantity of ZnO solution on pre-deposited WO3 thin films. XRD analysis reveals that stratified WO3/ZnO thin films are polycrystalline with monoclinic and hexagonal crystal structures for WO3 and ZnO respectively. The specific surface area of the stratified WO3/ZnO thin film is found to be 48.12 m2 g-1. The enhanced photoelectrocatalytic activity of stratified WO3/ZnO is mainly due to the suppressing the recombination of photo generated electron-hole pairs. The end result shows that the degradation percentage of phthalic acid (PA) using stratified WO3/ZnO photo electrode has reached 63.63% after 320 min. under sunlight illumination. The amount of mineralization of phthalic acid is studied with the help of chemical oxygen demand (COD) measurement.

  12. Dopant-induced modifications in structural and optical properties of ZnO thin films prepared by PLD

    Science.gov (United States)

    Hashmi, Jaweria Z.; Siraj, K.; Naseem, S.; Shaukat, S.

    2016-09-01

    The objective of the present work is to study the effect of yttrium doping concentration on the microstructure and optical behavior of ZnO thin films, deposited by pulsed laser deposition on silicon (001) substrates. The microstructural analysis of doped ZnO thin films shows columnar growth of the ZnO (002) plane under tensile stress, confirmed by Raman shifts of the E2 (high) mode. The optical properties are investigated by using a spectroscopic ellipsometer. Undoped and yttrium-doped ZnO films show high transparency in the visible region, and the estimated optical band gap energy is randomly shifted in the range 2.93-3.1 eV by increasing the yttrium doping level. Yttrium doping in ZnO is limited, which means that at doping concentrations higher than 3 wt.% of yttrium, the structural and optical properties show a shift towards those of undoped ZnO.

  13. Luminescence and structural properties of ZnO thin films annealing in air

    Energy Technology Data Exchange (ETDEWEB)

    Baca, R; Martinez, J [Centro de Investigacion de Dispositivos Semiconductores, BUAP, Puebla, Pue. C.P. 72570 (Mexico); Esparza, A [Centro de Ciencias Aplicadas y Desarrollo de TecnologIa - UNAM. C.P. 04510, Mexico D.F (Mexico); Kryshtab, T [Departamento de Ciencias de Materiales, ESFM - IPN, Mexico D.F (Mexico); Juarez, G; Solache, H; Andraca, J; Pena, R, E-mail: rbaca02006@yahoo.com.mx

    2010-02-15

    All ZnO thin films deposited on (001) silicon substrates by DC reactive magnetron sputtering were annealed in air atmosphere with different times at 800deg. C. The samples were studied by X-ray diffraction technique (XRD), atomic force microscopy (AFM) and photoluminescence (PL) measurements. XRD investigation showed that ZnO phase was hexagonal wurtzite structure growing along the (002) direction. The as grown ZnO films presented macrostrain and microstrain caused a shift of the line diffraction (002) and a broadening respectively. However after 1 hour annealing these strains disappear. The grain size of ZnO films increased with an increase of annealing time. The as-deposited reactive sputtering ZnO films resulted semi-insulating with poor PL response. After high temperature annealing in air, the crystallinity and the PL response considerably improved, but their semi-insulating property also increased. The PL spectra of the annealed samples showed well defined transitions close to the near-band-edge and a wide visible deep-level band emission (430-640 nm). The main interest of this work was to enhance the PL response and to identify the origin of deep-level luminescence bands. The AFM, PL and XRD results indicated that the ZnO films annealing have potential applications in optoelectronic devices.

  14. Preparation of Ni doped ZnO thin films by SILAR and their characterization

    Science.gov (United States)

    Mondal, S.; Mitra, P.

    2013-02-01

    Pure and nickel (Ni) doped zinc oxide (NZO) thin films were deposited on glass substrates from ammonium zincate bath using successive ion layer adsorption and reaction (SILAR). Characterization techniques such as XRD, TEM, SEM and EDX were utilized to investigate the effect of Ni doping on the microstructure of Ni:ZnO thin films. Structural characterization by X-ray diffraction reveals the polycrystalline nature of the films. Particle size shows slightly decreasing trend with increasing nickel impurification. The average particle size for pure ZnO is 22.75 nm and it reduces to 20.51 nm for 10 % Ni doped ZnO. Incorporation of Ni was confirmed from elemental analysis using EDX. The value of fundamental absorption edge is 3.23 eV for pure ZnO and it decreases to 3.19 eV for 10 % Ni:ZnO. The activation energy barrier value to electrical conduction process increases from 0.261 eV for pure ZnO to 0.293 eV for 10 % Ni doped ZnO.

  15. Characterizations of multilayer ZnO thin films deposited by sol-gel spin coating technique

    Science.gov (United States)

    Khan, M. I.; Bhatti, K. A.; Qindeel, Rabia; Alonizan, Norah; Althobaiti, Hayat Saeed

    In this work, zinc oxide (ZnO) multilayer thin films are deposited on glass substrate using sol-gel spin coating technique and the effect of these multilayer films on optical, electrical and structural properties are investigated. It is observed that these multilayer films have great impact on the properties of ZnO. X-ray Diffraction (XRD) confirms that ZnO has hexagonal wurtzite structure. Scanning Electron Microscopy (SEM) showed the crack-free films which have uniformly distributed grains structures. Both micro and nano particles of ZnO are present on thin films. Four point probe measured the electrical properties showed the decreasing trend between the average resistivity and the number of layers. The optical absorption spectra measured using UV-Vis. showed the average transmittance in the visible region of all films is 80% which is good for solar spectra. The performance of the multilayer as transparent conducting material is better than the single layer of ZnO. This work provides a low cost, environment friendly and well abandoned material for solar cells applications.

  16. Solution-based synthesis of cobalt-doped ZnO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Vempati, Sesha [School of Mathematics and Physics, Queen' s University Belfast, BT7 1NN (United Kingdom); Shetty, Amitha [Materials Research Center, Indian Institute of Science, Bangalore 560012 (India); Dawson, P., E-mail: p.dawson@qub.ac.uk [School of Mathematics and Physics, Queen' s University Belfast, BT7 1NN (United Kingdom); Nanda, K.K.; Krupanidhi, S.B. [Materials Research Center, Indian Institute of Science, Bangalore 560012 (India)

    2012-12-01

    Undoped and cobalt-doped (1-4 wt.%) ZnO polycrystalline, thin films have been fabricated on quartz substrates using sequential spin-casting and annealing of simple salt solutions. X-ray diffraction (XRD) reveals a wurzite ZnO crystalline structure with high-resolution transmission electron microscopy showing lattice planes of separation 0.26 nm, characteristic of (002) planes. The Co appears to be tetrahedrally co-ordinated in the lattice on the Zn sites (XRD) and has a charge of + 2 in a high-spin electronic state (X-ray photoelectron spectroscopy). Co-doping does not alter the wurzite structure and there is no evidence of the precipitation of cobalt oxide phases within the limits of detection of Raman and XRD analysis. Lattice defects and chemisorbed oxygen are probed using photoluminescence and Raman spectroscopy - crucially, however, this transparent semiconductor material retains a bandgap in the ultraviolet (3.30-3.48 eV) and high transparency (throughout the visible spectral regime) across the doping range. - Highlights: Black-Right-Pointing-Pointer Simple solution-based method for the fabrication of Co-doped ZnO thin films. Black-Right-Pointing-Pointer Evidence for Co substitution on Zn sites in + 2 oxidation state. Black-Right-Pointing-Pointer ZnO, with up to 4% Co doping, retains high transparency across visible spectrum. Black-Right-Pointing-Pointer Quenching of exciton photoluminescence linked to chemisorbed oxygen in Co-doped ZnO.

  17. Preparation of Aligned ZnO Nanorod Arrays on Sn-Doped ZnO Thin Films by Sonicated Sol-Gel Immersion Fabricated for Dye-Sensitized Solar Cell

    OpenAIRE

    Saurdi, I.; Mamat, M. H.; M. F. Malek; M. Rusop

    2014-01-01

    Aligned ZnO Nanorod arrays are deposited on the Sn-doped ZnO thin film via sonicated sol-gel immersion method. The structural, optical, and electrical properties of the Sn-doped ZnO thin films were investigated. Results show that the Sn-doped ZnO thin films with small grain size (~20 nm), high average transmittance (96%) in visible region, and good resistivity 7.7 × 102 Ω·cm are obtained for 2 at.% Sn doping concentration. The aligned ZnO nanorod arrays with large surface area were also obtai...

  18. Retracted: Study of the wettability of ZnO nanofilms

    Directory of Open Access Journals (Sweden)

    Ujjwal M Joshi

    2012-04-01

    Full Text Available Al-doped and un-doped ZnO thin films deposited on quartz substrates by the nebulized spray pyrolysis method were studied to investigate the wettability of the surface. The main objective of the present study was to investigate the wettability of ZnO thin film by changing the concentration of Al doping. Microstructure and water contact angles of the films were measured by scanning electron microscopy (SEM and using a contact angle goniometer. SEM studies revealed that the grain size within the film increases with the doping concentration. The contact angles were studied to see the effect of aluminum doping on the hydrophilicity of the film. ZnO films were found to be hydrophobic in nature. A good correlation was observed between the SEM micrographs and contact angle results. The nature of the film was found to change from being hydrophobic to hydrophilic after the treatment in low-pressure DC glow discharge plasma, which, however, was reversible with the storage time.

  19. Study of the wettability of ZnO nanofilms

    Science.gov (United States)

    Subedi, Deepak Prasad; Madhup, Dinesh Kumar; Sharma, Ashish; Joshi, Ujjwal Man; Huczko, Andrzej

    2012-04-01

    Al-doped and un-doped ZnO thin films deposited on quartz substrates by the nebulized spray pyrolysis method were studied to investigate the wettability of the surface. The main objective of the present study was to investigate the wettability of ZnO thin film by changing the concentration of Al doping. Microstructure and water contact angles of the films were measured by scanning electron microscopy (SEM) and using a contact angle goniometer. SEM studies revealed that the grain size within the film increases with the doping concentration. The contact angles were studied to see the effect of aluminum doping on the hydrophilicity of the film. ZnO films were found to be hydrophobic in nature. A good correlation was observed between the SEM micrographs and contact angle results. The nature of the film was found to change from being hydrophobic to hydrophilic after the treatment in low-pressure DC glow discharge plasma, which, however, was reversible with the storage time.

  20. Experimental Studies on Doped and Co-Doped ZnO Thin Films Prepared by RF Diode Sputtering

    OpenAIRE

    2009-01-01

    Our research on the growing and characterizing of p-type ZnO thin films, prepared by radio frequency (RF) diode sputtering, mono-doped with nitrogen, and co-doped with aluminium and nitrogen, is a response of the need from p-type ZnO thin films for device applications. The dopants determine the conductivity type of the film and its physical properties. We obtained p-type ZnO thin films by RF diode sputtering and using a nitrogen dopant source. The novelty in our approach is in the use of a pl...

  1. Pulsed laser deposition of piezoelectric ZnO thin films for bulk acoustic wave devices

    Energy Technology Data Exchange (ETDEWEB)

    Serhane, Rafik, E-mail: rserhane@cdta.dz [Centre for Development of Advanced Technologies, Cité 20 Août 1956, Baba Hassen, BP: 17, DZ-16303 Algiers (Algeria); Abdelli-Messaci, Samira; Lafane, Slimane; Khales, Hammouche; Aouimeur, Walid [Centre for Development of Advanced Technologies, Cité 20 Août 1956, Baba Hassen, BP: 17, DZ-16303 Algiers (Algeria); Hassein-Bey, Abdelkadder [Centre for Development of Advanced Technologies, Cité 20 Août 1956, Baba Hassen, BP: 17, DZ-16303 Algiers (Algeria); Micro and Nano Physics Group, Faculty of Sciences, University Saad Dahlab of Blida (USDB), BP. 270, DZ-09000 Blida (Algeria); Boutkedjirt, Tarek [Equipe de Recherche Physique des Ultrasons, Faculté de Physique, Université des Sciences et de la Technologie Houari Boumediene (USTHB), BP 32, El-Alia, Bab-Ezzouar, DZ-16111 Algiers (Algeria)

    2014-01-01

    Piezoelectric properties of ZnO thin films have been investigated for micro-electro-mechanical systems (MEMS). Wurtzite ZnO structure was prepared on different substrates (Si (1 0 0), Pt (1 1 1)/Ti/SiO{sub 2}/Si and Al (1 1 1)/SiO{sub 2}/Si) at different substrate temperatures (from 100 to 500 °C) by a pulsed laser deposition (PLD) technique. X-ray diffraction (XRD) characterization showed that the ZnO films were highly c-axis (0 0 2) oriented, which is of interest for various piezoelectric applications. Scanning electron microscopy (SEM) showed evidence of honeycomb-like structure on the surface and columnar structure on the cross-section. In the case of ZnO on Al, ZnO exhibited an amorphous phase at the ZnO/Al interface. The XRD measurements indicated that the substrate temperature of 300 °C was the optimum condition to obtain high quality (strongest (0 0 2) peak with the biggest associated grain size) of crystalline ZnO on Pt and on Al and that 400 °C was the optimum one on Si. ZnO on Al exhibits smallest rocking curve width than on Pt, leading to better crystalline quality. The ZnO films were used in bulk acoustic wave (BAW) transducer. Electrical measurements of the input impedance and S-Parameters showed evidence of piezoelectric response. The electromechanical coupling coefficient was evaluated as K{sub eff}{sup 2}=5.09%, with a quality factor Q{sub r} = 1001.4.

  2. Pulsed laser deposition of piezoelectric ZnO thin films for bulk acoustic wave devices

    Science.gov (United States)

    Serhane, Rafik; Abdelli-Messaci, Samira; Lafane, Slimane; Khales, Hammouche; Aouimeur, Walid; Hassein-Bey, Abdelkadder; Boutkedjirt, Tarek

    2014-01-01

    Piezoelectric properties of ZnO thin films have been investigated for micro-electro-mechanical systems (MEMS). Wurtzite ZnO structure was prepared on different substrates (Si (1 0 0), Pt (1 1 1)/Ti/SiO2/Si and Al (1 1 1)/SiO2/Si) at different substrate temperatures (from 100 to 500 °C) by a pulsed laser deposition (PLD) technique. X-ray diffraction (XRD) characterization showed that the ZnO films were highly c-axis (0 0 2) oriented, which is of interest for various piezoelectric applications. Scanning electron microscopy (SEM) showed evidence of honeycomb-like structure on the surface and columnar structure on the cross-section. In the case of ZnO on Al, ZnO exhibited an amorphous phase at the ZnO/Al interface. The XRD measurements indicated that the substrate temperature of 300 °C was the optimum condition to obtain high quality (strongest (0 0 2) peak with the biggest associated grain size) of crystalline ZnO on Pt and on Al and that 400 °C was the optimum one on Si. ZnO on Al exhibits smallest rocking curve width than on Pt, leading to better crystalline quality. The ZnO films were used in bulk acoustic wave (BAW) transducer. Electrical measurements of the input impedance and S-Parameters showed evidence of piezoelectric response. The electromechanical coupling coefficient was evaluated as Keff2    =    5 .0 9 %, with a quality factor Qr = 1001.4.

  3. Photocatalytic efficiency of reusable ZnO thin films deposited by sputtering technique

    Energy Technology Data Exchange (ETDEWEB)

    Ahumada-Lazo, R.; Torres-Martínez, L.M. [Universidad Autónoma de Nuevo León, Facultad de Ingeniería Civil, Departamento de Ecomateriales y Energía, Av. Universidad S/N Ciudad Universitaria, San Nicolás de los Garza, Nuevo León C.P. 66450, México (Mexico); Ruíz-Gómez, M.A. [Universidad Autónoma de Nuevo León, Facultad de Ingeniería Civil, Departamento de Ecomateriales y Energía, Av. Universidad S/N Ciudad Universitaria, San Nicolás de los Garza, Nuevo León C.P. 66450, México (Mexico); Departmento de Física Aplicada, CINVESTAV-IPN, Antigua Carretera a Progreso km 6, Mérida, Yucatán 97310, México (Mexico); Vega-Becerra, O.E. [Centro de Investigación en Materiales Avanzados S.C, Alianza norte 202, Parque de Investigación e Innovación Tecnológica, C.P. 66600 Apodaca Nuevo León, México (Mexico); and others

    2014-12-15

    Graphical abstract: - Highlights: • Decolorization of Orange G dye using highly c-axis-oriented ZnO thin films. • The flake-shaped film shows superior and stable photoactivity at a wide range of pH. • The highest photodecolorization was achieved at pH of 7. • The exposure of (101) and (100) facets enhanced the photoactivity. • ZnO thin films exhibit a promising performance as recyclable photocatalysts. - Abstract: The photocatalytic activity of ZnO thin films with different physicochemical characteristics deposited by RF magnetron sputtering on glass substrate was tested for the decolorization of orange G dye aqueous solution (OG). The crystalline phase, surface morphology, surface roughness and the optical properties of these ZnO films were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), atomic force microscopy (AFM) and UV–visible spectroscopy (UV–Vis), respectively. The dye photodecolorization process was studied at acid, neutral and basic pH media under UV irradiation of 365 nm. Results showed that ZnO films grow with an orientation along the c-axis of the substrate and exhibit a wurtzite crystal structure with a (002) preferential crystalline orientation. A clear relationship between surface morphology and photocatalytic activity was observed for ZnO films. Additionally, the recycling photocatalytic abilities of the films were also evaluated. A promising photocatalytic performance has been found with a very low variation of the decolorization degree after five consecutive cycles at a wide range of pH media.

  4. Comparative investigation on cation-cation (Al-Sn) and cation-anion (Al-F) co-doping in RF sputtered ZnO thin films: Mechanistic insight

    Science.gov (United States)

    Mallick, Arindam; Basak, Durga

    2017-07-01

    Herein, we report a comparative mechanistic study on cation-cation (Al-Sn) and cation-anion (Al-F) co-doped nanocrystalline ZnO thin films grown on glass substrate by RF sputtering technique. Through detailed analyses of crystal structure, surface morphology, microstructure, UV-VIS-NIR transmission-reflection and electrical transport property, the inherent characteristics of the co-doped films were revealed and compared. All the nanocrystalline films retain the hexagonal wurtzite structure of ZnO and show transparency above 90% in the visible and NIR region. As opposed to expectation, Al-Sn (ATZO) co-doped film show no enhanced carrier concentration consistent with the probable formation of SnO2 clusters supported by the X-ray photoelectron spectroscopy study. Most interestingly, it has been found that Al-F (AFZO) co-doped film shows three times enhanced carrier concentration as compared to Al doped and Al-Sn co-doped films attaining a value of ∼9 × 1020 cm-3 due to the respective cation and anion substitution. The carrier relaxation time increases in AFZO while it decreases significantly for ATZO film consistent with the concurrence of the impurity scattering in the latter.

  5. DFT study of Al doped armchair SWCNTs

    Energy Technology Data Exchange (ETDEWEB)

    Dhiman, Shobhna, E-mail: s-dhiman@hotmail.com [Department of Applied Science, PEC, University of Technology, Chandigarh -160012 (India); Rani, Anita [Guru Nanak College for Girls, Sri Muktsar Sahib, Punjab-152026 (India); Kumar, Ranjan; Dharamvir, Keya [Department of Physics, Panjab University, Chandigarh-160014 (India)

    2016-05-23

    Electronic properties of endohedrally doped armchair single-walled carbon nanotubes (SWCNTs) with a chain of six Al atoms have been studied using ab-initio density functional theory. We investigate the binding energy/atom, ionization potential, electron Affinity and Homo-Lumo gap of doped armchair SWNTs from (4,4) to (6,6) with two ends open. BE/dopant atom and ionization potential is maximum for (6, 6) doped armchair carbon nanotube; suggest that it is more stable than (4, 4) and (5, 5) doped tubes. HOMO - LUMO gap of Al doped arm chair carbon nanotubes decreases linearly with the increase in diameter of the tube. This shows that confinement induce a strong effect on electronic properties of doped tubes. These combined systems can be used for future nano electronics. The ab–initio calculations were performed with SIESTA code using generalized gradient approximation (GGA).

  6. Room temperature ferromagnetism of Ni, (Ni, Li), (Ni, N)-doped ZnO thin films

    Institute of Scientific and Technical Information of China (English)

    AU; ChakTong

    2010-01-01

    Ni-doped ZnO thin films (Ni concentration up to 10 mol%) were generated on Si (100) substrates by a sol-gel technique. The films showed wurtzite structure and no other phase was found. The chemical state of Ni was found to be bivalent by X-ray photoelectron spectroscopy. The results of magnetic measurements at room temperature indicated that the films were ferromagnetic, and magnetic moment decreased with rise of Ni concentration. The magnetization of Ni (10 mol%)-doped ZnO film annealed in nitrogen was lower than that annealed in argon, suggesting that the density of defects had an effect on ferromagnetism.

  7. Growth by atomic layer epitaxy and characterization of thin films of ZnO

    Energy Technology Data Exchange (ETDEWEB)

    Kopalko, K.; Lusakowska, E.; Paszkowicz, W.; Domagala, J.Z.; Szczerbakow, A.; Swiatek, K.; Dybko, K. [Institute of Physics, Polish Acad. of Sciences, Al. Lotnikow 32/46, 02-668 Warsaw (Poland); Wojcik, A.; Godlewski, M. [Institute of Physics, Polish Acad. of Sciences, Al. Lotnikow 32/46, 02-668 Warsaw (Poland); Dep. of Mathem. and Natural Sci. College of Science, Cardinal S. Wyszynski Univ., Warsaw (Poland); Godlewski, M.M. [Dept. of Physiology, Biochem., Pharmacology and Toxicology, Fac. of Veterinary Medicine, Warsaw Agriculture University, Warsaw (Poland)

    2005-02-01

    ABSTRACT Atomic layer epitaxy (ALE) was applied to grow thin films of monocrystalline and polycrystalline ZnO. Monocrystalline films were obtained only for GaN/Al{sub 2}O{sub 3} substrates, whereas use of sapphire, silicon or soda lime glass resulted in either 3D growth mode or in polycrystalline films showing preferential orientation along the c axis. Successful Mn doping of ZnO films is reported, when using organic Mn precursors. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  8. Controllable growth and characterization of highly aligned ZnO nanocolumnar thin films

    Science.gov (United States)

    Onuk, Zuhal; Rujisamphan, Nopporn; Murray, Roy; Bah, Mohamed; Tomakin, Murat; Shah, S. Ismat

    2017-02-01

    We investigated the effects of growth conditions during magnetron sputtering on the structural, morphological, and optical properties of nanostructured ZnO thin films. Undoped ZnO thin films are deposited onto p-type Si (100) and corning 7059 glass substrates by RF magnetron sputtering using a ZnO target in combination with various Ar-O2 sputtering gas mixtures at room temperature. The effect of the partial pressure of oxygen on the morphology of ZnO thin film structure and band alignment were investigated. Thickness, and therefore the growth rate of the samples measured from the cross-sectional SEM micrographs, is found to be strongly correlated with the oxygen partial pressure in the sputtering chamber. The optical transmittance spectrometry results show that the absorption edge shifts towards the longer wavelength at higher oxygen partial pressure. X-ray photoelectron spectroscopy (XPS) used for determining the surface chemical structure and valence band offsets show that conduction band can be controlled by changing the sputtering atmosphere.

  9. Growth and optical characteristics of high-quality ZnO thin films on graphene layers

    Directory of Open Access Journals (Sweden)

    Suk In Park

    2015-01-01

    Full Text Available We report the growth of high-quality, smooth, and flat ZnO thin films on graphene layers and their photoluminescence (PL characteristics. For the growth of high-quality ZnO thin films on graphene layers, ZnO nanowalls were grown using metal-organic vapor-phase epitaxy on oxygen-plasma treated graphene layers as an intermediate layer. PL measurements were conducted at low temperatures to examine strong near-band-edge emission peaks. The full-width-at-half-maximum value of the dominant PL emission peak was as narrow as 4 meV at T = 11 K, comparable to that of the best-quality films reported previously. Furthermore, the stimulated emission of ZnO thin films on the graphene layers was observed at the low excitation energy of 180 kW/cm2 at room temperature. Their structural and optical characteristics were investigated using X-ray diffraction, transmission electron microscopy, and PL spectroscopy.

  10. Electrical properties of silver Schottky contacts to ZnO thin films

    Institute of Scientific and Technical Information of China (English)

    LI Xin-kun; LI Qing-shan; LIANG De-chun; XU Yan-dong

    2009-01-01

    ZnO thin films are deposited on Al/Si substrates by the pulsed laser deposition (PLD) method. The XRD and SEM images of films are examined. Highly c-axis oriented ZnO thin films which have uniform compact surface morphology are fabricated. The size of surface grains is about 30 nm. The Schottky barrier ultraviolet detectors with silver Schottky contacts are made on ZnO thin films. The current-voltage characteristics are measured. The ideality contact factor between Ag and ZnO film is 1.22, while the barrier height is 0.908 e V. After annealing at 600 ℃ for 2h, the ideafity factor is 1.18 and the barrier height is 0.988 eV. With the illumination of 325 nm wavelength UV-light, the photocurrent-to-dark current ratios before and after annealing are 140.4 and 138.4 biased at 5 V, respectively. The photocurrents increase more than two orders of magnitude over the dark currents.

  11. Studies on nonvolatile resistance memory switching in ZnO thin films

    Indian Academy of Sciences (India)

    L M Kukreja; A K Das; P Misra

    2009-06-01

    Six decades of research on ZnO has recently sprouted a new branch in the domain of resistive random access memories. Highly resistive and c-axis oriented ZnO thin films were grown by us using d.c. discharge assisted pulsed laser deposition on Pt/Ti/SiO2/Si substrates at room temperature. The resistive switching characteristics of these films were studied in the top-bottom configuration using current–voltage measurements at room temperature. Reliable and repeated switching of the resistance of ZnO thin films was obtained between two well defined states of high and low resistance with a narrow dispersion and small switching voltages. Resistance ratios of the high resistance state to low resistance state were found to be in the range of 2–5 orders of magnitude up to 20 test cycles. The conduction mechanism was found to be dominated by the Ohmic behaviour in low resistance states, while Poole–Frenkel emission was found to dominate in high resistance state. The achieved characteristics of the resistive switching in ZnO thin films seem to be promising for nonvolatile memory applications.

  12. Preparation and characterization of nanostructured ZnO thin films for photoelectrochemical splitting of water

    Indian Academy of Sciences (India)

    Monika Gupta; Vidhika Sharma; Jaya Shrivastava; Anjana Solanki; A P Singh; V R Satsangi; S Dass; Rohit Shrivastav

    2009-02-01

    Nanostructured zinc oxide thin films (ZnO) were prepared on conducting glass support (SnO2: F overlayer) via sol–gel starting from colloidal solution of zinc acetate 2-hydrate in ethanol and 2-methoxy ethanol. Films were obtained by spin coating at 1500 rpm under room conditions (temperature, 28–35°C) and were subsequently sintered in air at three different temperatures (400, 500 and 600°C). The evolution of oxide coatings under thermal treatment was studied by glancing incidence X-ray diffraction and scanning electron microscopy. Average particle size, resistivity and bandgap energy were also determined. Photoelectrochemical properties of thin films and their suitability for splitting of water were investigated. Study suggests that thin films of ZnO, sintered at 600°C are better for photoconversion than the films sintered at 400 or 500°C. Plausible explanations have been provided.

  13. The formation of anomalous Hall effect depending on W atoms in ZnO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Can, Musa Mutlu, E-mail: musamutlucan@gmail.com [Faculty of Engineering and Natural Sciences, Nanotechnology Research and Application Center, Sabancı University, Tuzla, 34956 İstanbul (Turkey); CNR-SPIN, Universitá di Napoli “Federico II”, Compl. Univ. di Monte S. Angelo, Via Cintia, I-80126 Napoli (Italy); Shah, S. Ismat [Department of Physics and Astronomy, Department of Material Science and Engineering, University of Delaware, Newark, DE 19716 (United States); Fırat, Tezer [Department of Physics Engineering, Hacettepe University, Beytepe 06800 Ankara (Turkey)

    2014-06-01

    This article investigates the effects of intrinsic point defects and extrinsic W atoms on magneto electrical properties in the ZnO lattice. The analyses were accomplished for ∼0.5% W including ZnO thin films, grown using a radio frequency (RF) magnetron sputtering system. The polarized spin current dependent magnetic formation was investigated by longitudinal and transverse magneto electrical measurements in a temperature range of 5 K to 300 K. The positive magneto resistivity (PMR) ratios reached 28.8%, 12.7%, and 17.6% at 5 K for thin films, having different post-deposition annealing conditions as a consequence of ionic W dependent defects in the lattice. Furthermore, an anomalous Hall effect, originating from polarized spin currents, was understood from the split in Hall resistance versus magnetic field (R{sub xy}(H)) curves for the thin film with high amount of Zn{sup 2+} and W{sup 6+} ionic defects.

  14. Experiment and prediction on thermal conductivity of Al2O3/ZnO nano thin film interface structure

    Indian Academy of Sciences (India)

    Ping Yang; Liqiang Zhang; Haiying Yang; Dongjing Liu; Xialong Li

    2014-05-01

    We predict that there is a critical value of Al2O3/ZnO nano thin interface thickness based on two assumptions according to an interesting phenomenon, which the thermal conductivity (TC) trend of Al2O3/ZnO nano thin interface is consistent with that of relevant single nano thin interface when the nano thin interface thickness is > 300 nm; however, TC of Al2O3/ZnO nano thin interface is higher than that of relevant single nano thin interface when the thin films thickness is < 10 nm. This prediction may build a basis for the understanding of interface between two different oxide materials. It implies an idea for new generation of semiconductor devices manufacturing.

  15. Nanostructured hybrid ZnO thin films for energy conversion

    Directory of Open Access Journals (Sweden)

    Samantilleke Anura

    2011-01-01

    Full Text Available Abstract We report on hybrid films based on ZnO/organic dye prepared by electrodeposition using tetrasulfonated copper phthalocyanines (TS-CuPc and Eosin-Y (EoY. Both the morphology and porosity of hybrid ZnO films are highly dependent on the type of dyes used in the synthesis. High photosensitivity was observed for ZnO/EoY films, while a very weak photoresponse was obtained for ZnO/TS-CuPc films. Despite a higher absorption coefficient of TS-CuPc than EoY, in ZnO/EoY hybrid films, the excited photoelectrons between the EoY levels can be extracted through ZnO, and the porosity of ZnO/EoY can also be controlled.

  16. INFLUENCE OF ALUMINUM CONCENTRATION ON THE ELECTRICAL AND OPTICAL PROPERTIES OF ZnO THIN FILMS

    Directory of Open Access Journals (Sweden)

    Ebru GÜNGÖR

    2016-10-01

    Full Text Available Al:ZnO thin films having with different Al concentrations were deposited on glass substrates by a sol-gel technique. The effects of Al doping on the structural, optical and electrical properties of Al:ZnO were investigated using with XRD, optical transmittance and sheet resistance measurements. The concentration of zinc acetate was 0.1 M. Al content in the starting solution was varied from 0 to 20% as the molarity range. Optical transmittance spectra of the films in the form of Film/Glass were used to determine the film thickness and optical band gaps. The optical transmissions of Al:ZnO thin films were higher than 80% in the visible and near infrared region. The optical band gaps of Al:ZnO films decrease with increase of Al content. In order to obtain the average sheet resistance of the films the current and voltage through the probes have been measured for five different position by four-point probe method. The results showed that the sheet resistances of Al:ZnO thin films increased with the Al concentration. Considering the film thickness and geometric factor, the electrical resistivity values were computed. It was observed that the sheet resistance of AZO films up to 10% molarity of Al in the starting solution increased.

  17. Template-controlled piezoactivity of ZnO thin films grown via a bioinspired approach

    Science.gov (United States)

    Blumenstein, Nina J; Streb, Fabian; Walheim, Stefan; Schimmel, Thomas; Bill, Joachim

    2017-01-01

    Biomaterials are used as model systems for the deposition of functional inorganic materials under mild reaction conditions where organic templates direct the deposition process. In this study, this principle was adapted for the formation of piezoelectric ZnO thin films. The influence of two different organic templates (namely, a carboxylate-terminated self-assembled monolayer and a sulfonate-terminated polyelectrolyte multilayer) on the deposition and therefore on the piezoelectric performance was investigated. While the low negative charge of the COOH-SAM is not able to support oriented attachment of the particles, the strongly negatively charged sulfonated polyelectrolyte leads to texturing of the ZnO film. This texture enables a piezoelectric performance of the material which was measured by piezoresponse force microscopy. This study shows that it is possible to tune the piezoelectric properties of ZnO by applying templates with different functionalities. PMID:28243568

  18. Role of Ni doping on transport properties of ZnO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Dar, Tanveer Ahmad, E-mail: tanveerphysics@gmail.com; Agrawal, Arpana; Sen, Pratima [Laser Bhawan, School Of Physics, Devi Ahilaya University Takshashila Campus Khandwa Road Indore, Indore-452001 (India)

    2015-06-24

    Nickel doped (Ni=0.05) and undoped Zinc Oxide (ZnO) thin films have been prepared by Pulsed laser deposition (PLD) technique. The structural analysis of the films was done by X-ray diffraction (XRD) studies which reveal absence of any secondary phase in the prepared samples. UV transmission spectra show that Ni doping reduces the transparency of the films. X-ray Photoelectron spectroscopy (XPS) also shows the presence of metallic Ni along with +2 oxidation state in the sample. Low temperature magneto transport properties of the ZnO and NiZnO films are also discussed in view of Khosla fisher model. Ni doping in ZnO results in decrease in magnitude of negative MR.

  19. Photopatternable nano-composite (SU-8/ZnO) thin films for piezo-electric applications

    Science.gov (United States)

    Kandpal, Manoj; Sharan, Chandrashekhar; Poddar, Pankaj; Prashanthi, K.; Apte, Prakash R.; Ramgopal Rao, V.

    2012-09-01

    Photo-curable nanocomposite material was formulated by embedding ZnO nanoparticles into a SU-8 matrix and studied for its piezoelectric properties for low cost fabrication of self-powered nanodevices. The piezoelectric coefficient of ZnO nanoparticles was observed to be ranging between 15 and 23 pm/V, which is the highest reported. These experimental studies support the recent theoretical predictions where the piezoelectric coefficients in ZnO nanoparticles were found to be higher compared to the thin films because of the surface relaxation induced volume reductions in the nanometer scale. The photo-curable property of these polymer composite films is exploited to demonstrate fabrication of a micro-cantilever test structure.

  20. Electrodeposition of ZnO thin films on n-Si(100)

    Energy Technology Data Exchange (ETDEWEB)

    Dalchiele, E.A.; Giorgi, P.; Marotti, R.E. [Facultad de Ingenieria, Instituto de Fisica, Herrera y Reissig 565, C.C. 30, 11000 Montevideo (Uruguay); Martin, F.; Ramos-Barrado, J.R.; Ayouci, R.; Leinen, D. [Laboratorio de Materiales y Superficie, Unidad asociada al CSIC, Departamento de Fisica Aplicada and Ingenieria Quimica, Facultad de Ciencias, Universidad de Malaga, 29071 Malaga (Spain)

    2001-12-31

    In this study, ZnO thin films have been deposited onto monocrystalline n-type Si(100) by electrodeposition at different applied potentials. XRD shows a preferential orientation (0002) that increases when the applied cathodic potential increases. The XPS analysis presents a Zn/O composition close to stoichiometric. SEM micrographs show a compact structure with localized platelets with a grain size of about 10{mu}m. However, crystallite size determined by the Scherrer method shows a size close to 2.50x10{sup -2}{mu}m, then the grains can be considered as clusters of crystallites. Optical measurements were made on samples deposited on ITO/glass through the same procedures giving a band gap of 3.3eV in agreement with the reported values for ZnO at room temperature.

  1. Effect of Sm doping on the physical properties of ZnO thin films deposited by spray pyrolysis technique

    Science.gov (United States)

    Velusamy, P.; Babu, R. Ramesh; Aparna, K. T.

    2017-05-01

    Undoped and Sm doped ZnO thin films have been prepared by chemical spray pyrolysis method on a glass substrate at 430°C. The physical properties of undoped and Sm doped ZnO thin films are characterized by XRD, FE-SEM, UV-VIS spectroscopy, Hall measurement and PL analysis. XRD pattern reveals that all the films are polycrystalline nature. The FE-SEM study of CdO shows the smooth and uniform surface with the spherical shaped particle. The electrical study reveals the n-type semiconductor and the optical study shows that Sm doped ZnO thin films about 92% transparency and optical band gap vary between 3.266-3.276 eV. Sm doped ZnO thin films have strong green emission behavior.

  2. Influence of Urbach Energy with Solution Molarity on the Electrical Conductivity in Undoped ZnO Thin Films

    National Research Council Canada - National Science Library

    Said Benramache; Boubaker Benhaoua

    2016-01-01

    .... The model proposals were based on experimental data as discussed in our published paper. ZnO thin films were prepared into the ultrasonic spray method with different solution molarities on glass substrate at 350 °C...

  3. Effects of sapphire substrates surface treatment on the ZnO thin films grown by magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Wang Yinzhen [School of Physics and Telecommunication Engineering, South China Normal University, Guangzhou 510631 (China)], E-mail: agwyz@yahoo.com.cn; Chu Benli [School of Physics and Telecommunication Engineering, South China Normal University, Guangzhou 510631 (China)

    2008-06-01

    The surface treatment effects of sapphire substrate on the ZnO thin films grown by magnetron sputtering were studied. The sapphire substrates properties have been investigated by means of atomic force microscopy (AFM) and X-ray diffraction rocking curves (XRCs). The results show that sapphire substrate surfaces have the best quality by CMP with subsequent chemical etching. The surface treatment effects of sapphire substrate on the ZnO thin films were examined by X-ray diffraction (XRD) and photoluminescence (PL) measurements. Results show that the intensity of (0 0 2) diffraction peak of ZnO thin films on sapphire substrates treated by CMP with subsequent chemical etching was strongest, FWHM of (0 0 2) diffraction peak is the narrowest and the intensity of UV peak of PL spectrum is strongest, indicating surface treatment on sapphire substrate preparation may improve ZnO thin films crystal quality and photoluminescent property.

  4. (0 0 2-oriented growth and morphologies of ZnO thin films prepared by sol-gel method

    Directory of Open Access Journals (Sweden)

    Guo Dongyun

    2016-09-01

    Full Text Available Zinc acetate was used as a starting material to prepare Zn-solutions from solvents and ligands with different boiling temperature. The ZnO thin films were prepared on Si(1 0 0 substrates by spin-coating method. The effect of baking temperature and boiling temperature of the solvents and ligands on their morphologies and orientation was investigated. The solvents and ligands with high boiling temperature were favorable for relaxation of mechanical stress to form the smooth ZnO thin films. As the solvents and ligands with low boiling temperature were used to prepare Zn-solutions, the prepared ZnO thin films showed (0 0 2 preferred orientation. As n-propanol, 2-methoxyethanol, 2-(methylaminoethanol and monoethanolamine were used to prepare Zn-solutions, highly (0 0 2-oriented ZnO thin films were formed by adjusting the baking temperature.

  5. Effect of Oxidation Temperature on Characteristics of Thermally Oxidized ZnO Thin Films on Mica Substrates.

    Science.gov (United States)

    Moon, Jiyun; Kim, Younggyu; Kim, Byunggu; Leem, Jae-Young

    2015-11-01

    Muscovite mica is one of the promising alternatives to polymer substrates because of its good thermal resistivity, flexibility, and transparency. In this study, metallic Zn films with a thickness of 300 nm were deposited on mica substrates through thermal evaporation; the thin films were then oxidized by annealing at temperatures ranging from 350 to 550 degrees C. The structural and optical properties of thermally oxidized ZnO thin films were investigated. Diffraction peaks for ZnO (100) and (002) planes were observed only for the ZnO thin films oxidized at temperatures above 450 degrees C. These films consisted of relatively rough film-like structures, and the average transmittance of the films was greater than 70% in the visible region. The highest near-band-edge emission was observed for the ZnO thin films oxidized at 500 degrees C. Upon increasing the oxidation temperatures to 500 degrees C, the optical band gap was blue-shifted.

  6. Room-temperature ferromagnetism in Co-doped ZnO thin films prepared by sol-gel method

    Energy Technology Data Exchange (ETDEWEB)

    Belghazi, Y. [Laboratoire de Physique des Materiaux, Faculte des Sciences, B.P. 1014, Rabat (Morocco); IPCMS-GMI (UMR 7504 du CNRS) (ECPM-ULP), 23 rue du Loess, BP 43, F-67034 Strasbourg Cedex 2 (France); Schmerber, G. [IPCMS-GMI (UMR 7504 du CNRS) (ECPM-ULP), 23 rue du Loess, BP 43, F-67034 Strasbourg Cedex 2 (France); Colis, S. [IPCMS-GMI (UMR 7504 du CNRS) (ECPM-ULP), 23 rue du Loess, BP 43, F-67034 Strasbourg Cedex 2 (France); Rehspringer, J.L. [IPCMS-GMI (UMR 7504 du CNRS) (ECPM-ULP), 23 rue du Loess, BP 43, F-67034 Strasbourg Cedex 2 (France); Berrada, A. [Laboratoire de Physique des Materiaux, Faculte des Sciences, B.P. 1014, Rabat (Morocco); Dinia, A. [IPCMS-GMI (UMR 7504 du CNRS) (ECPM-ULP), 23 rue du Loess, BP 43, F-67034 Strasbourg Cedex 2 (France)]. E-mail: aziz.dinia@ipcms.u-strasbg.fr

    2007-03-15

    We report on room-temperature ferromagnetism in Co-doped ZnO thin films grown onto Si(100) and SiO{sub 2} substrates using the spin-coating technique. X-ray diffraction measurements show that the films have the wurtzite structure with a preferential orientation along the c-axis. UV-Visible spectroscopy has shown that the Co{sup 2+} ions are substituted to Zn{sup 2+} ions in ZnO matrix. The analysis of the magnetization measurements indicates that the observed ferromagnetism in ZnO and Co-doped ZnO films is extrinsic and can be due to a pollution.

  7. Photovoltaic properties of undoped ZnO thin films prepared by the spray pyrolysis technique

    Energy Technology Data Exchange (ETDEWEB)

    Ikhmayies, S.J. [Applied Science Private Univ., Amman (Jordan). Dept. of Physics; Abu El-Haija, N.M.; Ahmad-Bitar, R.N. [Jordan Univ., Amman (Jordan). Dept. of Physics

    2009-07-01

    Zinc oxide (ZnO) can be used as a window material, transparent electrode and active layer in different types of solar cells, UV emitters, and UV sensors. In addition to being low cost, ZnO is more abundant than indium tin oxide. ZnO is non toxic and has a high chemical stability in reduction environments. When ZnO films are made without any intentional doping, they exhibit n-type conductivity. ZnO thin films can be prepared by reactive sputtering, laser ablation, chemical-vapour deposition, laser molecular-beam epitaxy, thermal evaporation, sol-gel, atomic layer deposition and spray pyrolysis, with the latter being simple, inexpensive and adaptable to large area depositions. In this work ZnCl{sub 2} was used as a source of Zn where it was dissolved in distilled water. The structural, electrical and optical properties of the films were investigated due to their important characteristic for solar cell applications. Polycrystalline ZnO thin films were deposited on glass substrate by spray pyrolysis using a home-made spraying system at substrate temperature of 450 degrees C. The films were characterized by recording and analyzing their I-V plots, their transmittance, X-ray diffraction and SEM micrographs. There resistivity was found to be about 200 ohms per cm and their bandgap energy about 3.27 eV. X-ray diffraction patterns revealed that the films have a hexagonal wurtzite structure and are highly ordered with a preferential orientation (002). SEM images revealed that the substrates are continuously covered and the surface of the film is uniform. 16 refs., 4 figs.

  8. Influence of annealing temperature on ZnO thin films grown by dual ion beam sputtering

    Indian Academy of Sciences (India)

    Sushil Kumar Pandey; Saurabh Kumar Pandey; Vishnu Awasthi; Ashish Kumar; Uday P Deshpande; Mukul Gupta; Shaibal Mukherjee

    2014-08-01

    We have investigated the influence of in situ annealing on the optical, electrical, structural and morphological properties of ZnO thin films prepared on -type Si(100) substrates by dual ion beam sputtering deposition (DIBSD) system. X-ray diffraction (XRD) measurements showed that all ZnO films have (002) preferred orientation. Full-width at half-maximum (FWHM) of XRD from the (002) crystal plane was observed to reach to a minimum value of 0.139° from ZnO film, annealed at 600 °C. Photoluminescence (PL) measurements demonstrated sharp near-band-edge emission (NBE) at ∼ 380 nm along with broad deep level emissions (DLEs) at room temperature. Moreover, when the annealing temperature was increased from 400 to 600 °C, the ratio of NBE peak intensity to DLE peak intensity initially increased, however, it reduced at further increase in annealing temperature. In electrical characterization as well, when annealing temperature was increased from 400 to 600 °C, room temperature electron mobility enhanced from 6.534 to 13.326 cm2/V s, and then reduced with subsequent increase in temperature. Therefore, 600 °C annealing temperature produced good-quality ZnO film, suitable for optoelectronic devices fabrication. X-ray photoelectron spectroscopy (XPS) study revealed the presence of oxygen interstitials and vacancies point defects in ZnO film annealed at 400 °C.

  9. Influence of laser doping on nanocrystalline ZnO thin films gas sensors

    Directory of Open Access Journals (Sweden)

    Yue Hou

    2017-08-01

    Full Text Available The effect of laser doping of Al on the gas sensing behavior of nanocrystalline ZnO thin films is reported. The doping of Al was carried out by the spin-coating of Al-precursors on nanocrystalline ZnO films followed by a pulsed laser irradiation. The laser-doped films were characterized as a function of laser power density by measuring the optical, structural, electrical, morphological and gas sensing properties of ZnO films. It was found that the laser doping process resulted in an increase of electrical conductivity of ZnO films. The performance of gas sensor was investigated for different concentrations of H2 and NH3 in the air. The results indicate that the laser doping process can be utilized to improve the sensor characteristics such as sensitivity and response time by optimization of laser power density. The optimum laser power is interpreted as the critical power level required to compete the effective doping versus developing the effective grain boundaries. Also, the selectivity of laser-doped ZnO sensors for H2 was studied for a likelihood practical gas mixture composed of H2, NH3 and CH4. It is found that these films can be optimized to develop H2 and NH3 sensors in PPM level with a higher selectivity over other reducing gases.

  10. Modification of ZnO Thin Films by Ni, Cu, and Cd Doping*1

    Science.gov (United States)

    Jiménez-González, A. E.

    1997-02-01

    With the propose of investigating the effect of transition elements in ZnO thin films prepared by the Successive Ion Layer Adsorption and Reaction (SILAR) technique, the deposition solutions were chemically impurified with Ni, Cu, and Cd, as elements of the Ib, IIb, and VIIIa groups. X-ray fluorescence (XRF) analyses confirm that the impurification with Ni and Cu in fact took place but the impurification with Cd did not, while the XRD analyses show that foras preparedand Ni-impurified annealed films, the crystallites are almost oriented along thecaxis. The electrical properties of the ZnO films were also modified with the impurification. After annealing in air (450°C) the dark conductivity of the films was increased in the case of Ni and Cd impurification up to 1.80×10-3and 1.86×10-2[Ω cm]-1, respectively, but it decreased drastically in the case of Cu to 5.51×10-7[Ω cm]-1, as referred to the dark conductivity (1.86×10-4[Ω cm]-1) of the pure ZnO sample. The measured activation energy for the electrical conductivity of the modified ZnO thin films is 55 meV for the Ni modification, indicating the existence of donor levels. On the other hand, the Cu modification increases the activation energy up to 132 meV, which is higher than the activation energy for pure ZnO thin films (98 meV).

  11. MICROSTRUCTURE AND PROPERTIES OF ANNEALED ZnO THIN FILMS DEPOSITED BY MAGNETRON SPUTTERING

    Institute of Scientific and Technical Information of China (English)

    J. Lee; W. Gao; Z. Li; M. Hodgson; A. Asadov; J. Metson

    2005-01-01

    ZnO thin films were deposited on a glass substrate by dc (direct current) and rf (radio frequency) magnetron sputtering. Post-deposition annealing was performed in different atmospheres and at different temperatures. The correlation of the annealing conditions with the microstructure and properties of the ZnO films were investigated by ultraviolet-visible spectroscopy, X-ray diffraction, conductivity measurement and scanning electron microscopy. Only the strong 002peak could be observed by X-ray diffraction. The post-deposition annealing of ZnO films was found to alter the film's microstructure and properties, including crystallinity, porosity, grain size, internal stress level and resistivity. It was also found that after annealing, the conductivity of poorly conductive samples often improved. However, annealing does not improve the conductivity of samples with high conductivity prior to annealing. The resistivity of as-grown films annealing on the conductivity of ZnO, it is believed that annealing may alter the presence and distribution of oxygen defects, reduce the lattice stress, cause diffusion, grain coarsening and recrystallization. Annealing will reduce the density of grain boundaries in less dense films,which may decrease the resistivity of the films. On the other hand, annealing may also increase the porosity of thin films, leading to an increase in resistivity.

  12. Polyelectrolyte-assisted preparation and characterization of nanostructured ZnO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Jia, Shijun

    2005-05-15

    The present work focuses on the synthesis and characterization of nanostructured ZnO thin films onto silicon wafers modified by self-assembled-monolayers via chemical bath deposition. Two precursor solutions were designed and used for the film deposition, in which two different polymers were introduced respectively to control the growth of the ZnO colloidal particles in solution. ZnO films were deposited from an aqueous solution containing zinc salt and hexamethylenetetramine (HMTA) in the presence of a graft-copolymer (P (MAA{sub 0.50}-co(MAA-EO{sub 20}){sub 0.50}){sub 70}). A film-formation-diagram was established based on the results obtained by scanning electron microscopy (SEM) and atomic force microscopy (AFM), which describes the influence of the concentration of HMTA and copolymer on the ZnO film formation. According to the film morphology, film formation can be classified into three categories: (a) island-like films, (b) uniform films and (c) canyon-like films. The ZnO films annealed at temperatures of 450 C, 500 C, 600 C and 700 C were examined by X-ray diffraction (XRD) and transmission electron microscopy (TEM). After annealing, the films are polycrystalline ZnO with wurtzite structure. XRD measurements indicate that with increasing annealing temperature, the average grain size increases accordingly and the crystallinity of the films is improved. Upon heating to 600 C, the ZnO films exhibit preferred orientation with c-axis normal to substrate, whereas the films annealed at 700 C even show a more explicit texture. By annealing at temperatures above 600 C the ZnO film reacts with the substrate to form an interfacial layer of Zn{sub 2}SiO{sub 4}, which grows thicker at elevated annealing temperatures. The ZnO films annealed at 600 C and 700 C show strong UV emission. Another non-aqueous solution system for ZnO thin film deposition was established, in which 2- propanol was used as a solvent and Zn(CH3COO){sub 2}.2H{sub 2}O as well as NaOH as reactants

  13. Effect of substrate temperature on structural and optical properties of spray deposited ZnO thin films

    Directory of Open Access Journals (Sweden)

    Larbah Y.

    2015-09-01

    Full Text Available Undoped ZnO thin films have been prepared on glass substrates at different substrate temperatures by spray pyrolysis method. The effect of temperature on the structural, morphological and optical properties of n-type ZnO films was studied. The X-ray diffraction (XRD results confirmed that the ZnO thin films were polycrystalline with wurtzite structure. Scanning electron microscopy (SEM measurements showed that the surface morphology of the films changed with temperature. The studies demonstrated that the ZnO film had a transmission of about 85 % and energy gap of 3.28 eV at 450 °C. The RBS measurements revealed that ZnO layers with a thickness up to 200 nm had a good stoichiometry.

  14. A comparative study of physico-chemical properties of CBD and SILAR grown ZnO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Jambure, S.B.; Patil, S.J.; Deshpande, A.R.; Lokhande, C.D., E-mail: l_chandrakant@yahoo.com

    2014-01-01

    Graphical abstract: Schematic model indicating ZnO nanorods by CBD (Z{sub 1}) and nanograins by SILAR (Z{sub 2}). - Highlights: • Simple methods for the synthesis of ZnO thin films. • Comparative study of physico-chemical properties of ZnO thin films prepared by CBD and SILAR methods. • CBD outperforms SILAR method. - Abstract: In the present work, nanocrystalline zinc oxide (ZnO) thin films have been successfully deposited onto glass substrates by simple and economical chemical bath deposition (CBD) and successive ionic layer adsorption reaction (SILAR) methods. These films were further characterized for their structural, optical, surface morphological and wettability properties. The X-ray diffraction (XRD) patterns for both CBD and SILAR deposited ZnO thin films reveal the highly crystalline hexagonal wurtzite structure. From optical studies, band gaps obtained are 2.9 and 3.0 eV for CBD and SILAR deposited thin films, respectively. The scanning electron microscope (SEM) patterns show growth of well defined randomly oriented nanorods and nanograins on the CBD and SILAR deposited samples, respectively. The resistivity of CBD deposited films (10{sup 2} Ω cm) is lower than that of SILAR deposited films (10{sup 5} Ω cm). Surface wettability studies show hydrophobic nature for both films. From the above results it can be concluded that CBD grown ZnO thin films show better properties as compared to SILAR method.

  15. Linear and nonlinear optical investigations of nano-scale Si-doped ZnO thin films: spectroscopic approach

    Science.gov (United States)

    Jilani, Asim; Abdel-wahab, M. Sh.; Zahran, H. Y.; Yahia, I. S.; Al-Ghamdi, Attieh A.

    2016-09-01

    Pure and Si-doped ZnO (SZO) thin films at different concentration of Si (1.9 and 2.4 wt%) were deposited on highly cleaned glass substrate by radio frequency (DC/RF) magnetron sputtering. The morphological and structural investigations have been performed by atomic force electron microscope (AFM) and X-ray diffraction (XRD). The X-ray photoelectron spectroscopy was employed to study the composition and the change in the chemical state of Si-doped ZnO thin films. The optical observations like transmittance, energy band gap, extinction coefficient, refractive index, dielectric loss of pure and Si-doped ZnO thin films have been calculated. The linear optical susceptibility, nonlinear refractive index, and nonlinear optical susceptibility were also studied by the spectroscopic approach rather than conventional Z-scan method. The energy gap of Si-doped ZnO thin films was found to increase as compared to pure ZnO thin films. The crystallinity of the ZnO thin films was effected by the Si doping. The O1s spectra in pure and Si-doped ZnO revealed the bound between O-2 and Zn+2 ions and reduction in the surface oxygen with the Si doping. The chemical state analysis of Si 2p showed the conversation of Si to SiOx and SiO2. The increase in the first-order linear optical susceptibility χ (1) and third-order nonlinear optical susceptibility χ (3) was observed with the Si doping. The nonlinear studies gave some details about the applications of metal oxides in nonlinear optical devices. In short, this study showed that Si doping through sputtering has effected on the structural, surface and optical properties of ZnO thin films which could be quite useful for advanced applications such as metal-oxide-based optical devices.

  16. Design and fabrication of a MEMS Lamb wave device based on ZnO thin film

    Energy Technology Data Exchange (ETDEWEB)

    Liu Mengwei; Li Junhong; Ma Jun; Wang Chenghao, E-mail: liumw@mail.ioa.ac.cn [Institute of Acoustics, Chinese Academy of Sciences, Beijing 100190 (China)

    2011-04-15

    This paper presents the design and fabrication of a Lamb wave device based on ZnO piezoelectric film. The Lamb waves were respectively launched and received by both Al interdigital transducers. In order to reduce the stress of the thin membrane, the ZnO/Al/LTO/Si{sub 3}N{sub 4}/Si multilayered thin plate was designed and fabricated. A novel method to obtain the piezoelectric constant of the ZnO film was used. The experimental results for characterizing the wave propagation modes and their frequencies of the Lamb wave device indicated that the measured center frequency of antisymmetric A{sub 0} and symmetric S{sub 0} modes Lamb wave agree with the theoretical predictions. The mass sensitivity of the MEMS Lamb wave device was also characterized for gravimetric sensing application. (semiconductor devices)

  17. Semiconducting Properties of Swift Au Ion-Irradiated ZnO Thin Films at Room Temperature

    Science.gov (United States)

    Kwon, Sera; Park, Hyun-Woo; Chung, Kwun-Bum

    2017-02-01

    The semiconducting properties of Au ion-irradiated ZnO thin films were investigated as a function of ion irradiation dose at room temperature. The Au ion irradiation was conducted with acceleration energy of 130 MeV in the ion dose range from 1 × 1011 to 5 × 1012 ions/cm2. The physical properties showed no change regardless of the Au ion irradiation dose; however, the electrical properties of Au ion-irradiated ZnO thin films changed, depending on the Au ion irradiation dose. The electronic structure drastically changed with the evolution of hybridized molecular orbital structure for the conduction band and band edge states below the conduction band. These remarkable changes in electronic structure correlate with changes in electrical properties, such as carrier concentration and mobility.

  18. Design and fabrication of a MEMS Lamb wave device based on ZnO thin film*

    Institute of Scientific and Technical Information of China (English)

    Liu Mengwei; Li Junhong; Ma Jun; Wang Chenghao

    2011-01-01

    This paper presents the design and fabrication of a Lamb wave device based on ZnO piezoelectric film.The Lamb waves were respectively launched and received by both Al interdigital transducers. In order to reduce the stress of the thin membrane, the ZnO/A1/LTO/Si3N4/Si multilayered thin plate was designed and fabricated. A novel method to obtain the piezoelectric constant of the ZnO film was used. The experimental results for characterizing the wave propagation modes and their frequencies of the Lamb wave device indicated that the measured center frequency of antisymmetric A0 and symmetric S0 modes Lamb wave agree with the theoretical predictions. The mass sensitivity of the MEMS Lamb wave device was also characterized for gravimetric sensing application.

  19. Comparative study of ZnO thin films prepared by different sol-gel route

    Directory of Open Access Journals (Sweden)

    F Esmaieli Ghodsi

    2012-03-01

    Full Text Available   Retraction Notice    The paper "Comparative study of ZnO thin films prepared by different sol-gel route" by H. Absalan and F. E. Ghodsi, which appeared in Iranian Journal of Physics Research, Vol. 11, No. 4, 423-428 (in Farsi is translation of the paper "Comparative Study of ZnO Thin Films Prepared by Different Sol-Gel Route" by F. E. Ghodsi and H. Absalan, which appeared in ACTA PHYSICA POLONICA A, Vol 118 (2010 (in English and for this reason is retracted from this journal.The corresponding author  (and also the first author is the only responsible person for this action.   

  20. Ion-Irradiation-Induced Ferromagnetism in Undoped ZnO Thin Films

    Science.gov (United States)

    2013-01-01

    Ion-irradiation-induced ferromagnetism in undoped ZnO thin filmsq Siddhartha Mal a,⇑, Sudhakar Nori a, J. Narayan a, J.T. Prater b, D.K. Avasthi c...S, Narayan J, Nori S, Prater JT, Kumar D. Solid State Commun 2010;150:1660. [8] Mal S, Nori S, Jin C, Narayan J, Nellutla S, Smirnov AI, et al. J

  1. Epitaxial Properties of Co-Doped ZnO Thin Films Grown by Plasma Assisted Molecular Beam Epitaxy

    Institute of Scientific and Technical Information of China (English)

    CAO Qiang; DENG Jiang-Xia; LIU Guo-Lei; CHEN Yan-Xue; YAN Shi-Shen

    2007-01-01

    High quality Co-doped ZnO thin films are grown on single crystalline Al2O3(0001) and ZnO(0001) substrates by oxygen plasma assisted molecular beam epitaxy at a relatively lower substrate temperature of 450 ℃. The epitaxial conditions are examined with in-situ reflection high energy electron diffraction (RHEED) and ex-situ high resolution x-ray diffraction (HRXRD). The epitaxial thin films are single crystal at film thickness smaller than 500nm and nominal concentration of Co dopant up to 20%. It is indicated that the Co cation is incorporated into the ZnO matrix as Co2+ substituting Zn2+ ions. Atomic force microscopy shows smooth surfaces with rms roughness of 1.9nm. Room-temperature magnetization measurements reveal that the Co-doped ZnO thin films are ferromagnetic with Curie temperatures TC above room temperature.

  2. Effects of nitrogen on the growth and optical properties of ZnO thin films grown by pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Cui, J B; Thomas, M A; Soo, Y C; Kandel, H; Chen, T P [Department of Physics and Astronomy, University of Arkansas at Little Rock, Little Rock, AR 72204 (United States)

    2009-08-07

    ZnO thin films were grown using pulsed laser deposition by ablating a Zn target in various mixtures of O{sub 2} and N{sub 2}. The presence of N{sub 2} during deposition was found to affect the growth of the ZnO thin films and their optical properties. Small N{sub 2} concentrations during growth led to strong acceptor-related photoluminescence (PL), while larger concentrations affected both the intensity and temperature dependence of the emission peaks. In addition, the PL properties of the annealed ZnO thin films are associated with the N{sub 2} concentration during their growth. The possible role of nitrogen in ZnO growth and annealing is discussed.

  3. Effect of Sb2O3-doped on optical absorption of ZnO thin film

    Institute of Scientific and Technical Information of China (English)

    CHANG Chun-rong; LI Zi-quan; XU Yun-yun

    2006-01-01

    Sb2O3 doped ZnO thin film was prepared by RF magnetron sputtering technique.The influence of Sb2O3 on the structure and the optical absorption of ZnO thin film was studied by XPS,XRD apparatuses and UV-Vis spectrophotometer.The results show that doped Sb2O3 has affected atomic and electronic structures,growth modes of crystal grains and optical absorption of ZnO.The element Sb exists in many forms in the film including transpositional atoms and compounds such as Sb2O3,Zn7Sb2O14 etc.ZnO crystal grains grow in mixing directions.The lattice relaxation and the content of second phases increase when more Sb is doped.The UVA absorption of doped ZnO thin film increases obviously.The ultraviolet absorption peak narrows,absorption intensity increases,the absorption margin becomes steep and moves to shorter wavelength of about 5 nm,and the visible absorption increases in some sort.

  4. Engineering the switching dynamics of TiOx-based RRAM with Al doping

    Science.gov (United States)

    Trapatseli, Maria; Khiat, Ali; Cortese, Simone; Serb, Alexantrou; Carta, Daniela; Prodromakis, Themistoklis

    2016-07-01

    Titanium oxide (TiOx) has attracted a lot of attention as an active material for resistive random access memory (RRAM), due to its versatility and variety of possible crystal phases. Although existing RRAM materials have demonstrated impressive characteristics, like ultra-fast switching and high cycling endurance, this technology still encounters challenges like low yields, large variability of switching characteristics, and ultimately device failure. Electroforming has been often considered responsible for introducing irreversible damage to devices, with high switching voltages contributing to device degradation. In this paper, we have employed Al doping for tuning the resistive switching characteristics of titanium oxide RRAM. The resistive switching threshold voltages of undoped and Al-doped TiOx thin films were first assessed by conductive atomic force microscopy. The thin films were then transferred in RRAM devices and tested with voltage pulse sweeping, demonstrating that the Al-doped devices could on average form at lower potentials compared to the undoped ones and could support both analog and binary switching at potentials as low as 0.9 V. This work demonstrates a potential pathway for implementing low-power RRAM systems.

  5. Structural, morphological, optical and opto-thermal properties of Ni-doped ZnO thin films using spray pyrolysis chemical technique

    Indian Academy of Sciences (India)

    S Rajeh; A Barhoumi; A Mhamdi; G Leroy; B Duponchel; M Amlouk; S Guermazi

    2016-02-01

    Nickel-doped zinc oxide thin films (ZnO : Ni) at different percentages were deposited on glass substrates using a chemical spray technique. The effect of Ni concentration on the structural, morphological, optical and photoluminescence (PL) properties of the ZnO : Ni thin films were investigated. X-ray diffraction analysis revealed that all films consist of single phase ZnO and was well crystallized in würtzite phase with the crystallites preferentially oriented towards the (002) direction parallel to the c-axis. The optical transmittance measurement was found to be higher than 90%, the optical band gap values of ZnO thin films decreased after doping from 3.29 to 3.21 eV. A noticeable change in optical constants was observed between undoped and Ni-doped ZnO. Room-temperature PL is observed for ZnO, and Ni-doped ZnO thin films.

  6. Structural and optical properties of Ni added ZnO thin films deposited by sol-gel method

    Science.gov (United States)

    Murugan, R.; Vijayaprasath, G.; Mahalingam, T.; Anandhan, N.; Ravi, G.

    2014-04-01

    Pure and Ni added zinc oxide thin films were prepared by sol-gel method using spin-coating technique on glass substrates. The influences of nickel on ZnO thin films are characterized by Powder X-ray diffraction study. Pure and Ni added thin films are hexagonal wurtzite structure without any secondary phase in c-axis orientation. The SEM images of thin films show uniform sphere like particles covered completely on glass substrates. All the films exhibit transmittance of 85-95% in the visible range up to 800nm and cut-off wavelength observed at 394 nm corresponding to the fundamental absorption of ZnO. The photoluminescence property for pure and Ni added ZnO thin films has been studied and results are presented in detail.

  7. Performance Evaluation of ZnO based Rare Earth Element Doped Thin Films

    Directory of Open Access Journals (Sweden)

    Manish Sharma

    2013-10-01

    Full Text Available In DMS materials, a small fraction of a host semiconductor cation is substituted by magnetic ions. We chose as semiconducting host the transparent ZnO, with a bandgap of 3.3 eV at room temperature. Studies on ZnO doped with 3d transition metals indicated only small magnetic moments. The more recent results for Gd in GaN, indicating high magnetic moments, motivated us to investigate ZnO thin films doped with rare earth (RE metal ions. For the 3d transition metals, the 3d electrons are exterior and delocalized; leading to strong direct exchange interactions and high Curie temperatures, but often the orbital momentum is zero, leading to small total magnetic moments per atom. In RE metals, the 4f electrons are localized, exchange interactions are indirect, via 5d or 6s conduction electrons, but the high orbital momentum is leading to high total magnetic moments per atom, like 3.27μB for Nd. The Curie point for Nd is 19 K. In this paper we present the results of our study on ZnO films doped with Nd. Hall measurements are performed to investigate the electrical properties of films. Here we prepared and investigated ZnO films doped with different concentration of Nd. The films are grown on a-plane Al2O3 or SiO2 substrates. Hall investigations of electrical properties revealed the presence of a degenerate, highly conducting, film–substrate interface layer for the films grown on Al2O3; such an effect can be avoided, for example, by using SiO2 substrates. Magnetotransport measurements indicated no anomalous Hall effect, but a pronounced negative magneto resistance ratio that can be interpreted as a paramagnetic response of the system to the applied magnetic field. We would like to proceed with the surface sensitive techniques for investigating magnetic properties of ZnO:RE thin films.

  8. The effect of heat treatment on the physical properties of sol-gel derived ZnO thin films

    Science.gov (United States)

    Raoufi, Davood; Raoufi, Taha

    2009-03-01

    Zinc oxide (ZnO) thin films were deposited on microscope glass substrates by sol-gel spin coating method. Zinc acetate (ZnAc) dehydrate was used as the starting salt material source. A homogeneous and stable solution was prepared by dissolving ZnAc in the solution of monoethanolamine (MEA). ZnO thin films were obtained after preheating the spin coated thin films at 250 °C for 5 min after each coating. The films, after the deposition of the eighth layer, were annealed in air at temperatures of 300 °C, 400 °C and 500 °C for 1 h. The effect of thermal annealing in air on the physical properties of the sol-gel derived ZnO thin films are studied. The powder and its thin film were characterized by X-ray diffractometer (XRD) method. XRD analysis revealed that the annealed ZnO thin films consist of single phase ZnO with wurtzite structure (JCPDS 36-1451) and show the c-axis grain orientation. Increasing annealing temperature increased the c-axis orientation and the crystallite size of the film. The annealed films are highly transparent with average transmission exceeding 80% in the visible range (400-700 nm). The measured optical band gap values of the ZnO thin films were between 3.26 eV and 3.28 eV, which were in the range of band gap values of intrinsic ZnO (3.2-3.3 eV). SEM analysis of annealed thin films has shown a completely different surface morphology behavior.

  9. Defect-band mediated ferromagnetism in Gd-doped ZnO thin films

    KAUST Repository

    Venkatesh, S.

    2015-01-07

    Gd-doped ZnO thin films prepared by pulsed laser deposition with Gd concentrations varying from 0.02–0.45 atomic percent (at. %) showed deposition oxygen pressure controlled ferromagnetism. Thin films prepared with Gd dopant levels (

  10. Gd doping effect on structural, electrical and magnetic properties of ZnO thin films synthesized by sol-gel spin coating technique

    Science.gov (United States)

    Kumar, Sanjeev; Thangavel, Rajalingam

    2017-03-01

    Nanocrystalline Gd-doped ZnO thin films were deposited on sapphire (0001) substrates using sol-gel spin coating technique. The structural and optical properties of deposited thin films were characterized by X-ray diffraction (XRD) and micro Raman spectroscopy. Structural and optical studies show that the doped Gd ions occupy Zn sites retaining the wurtzite symmetry. Photoluminescence (PL) studies reveal the presence of oxygen vacancies in Gd doped ZnO thin films. The resistivity of Gd doped ZnO thin film decreases with increase in Gd doping upto 4%. Gd-doped ZnO films demonstrate weak magnetic ordering at room temperature.

  11. Optical and electrical characterization of aluminium doped ZnO layers

    Science.gov (United States)

    Major, C.; Nemeth, A.; Radnoczi, G.; Czigany, Zs.; Fried, M.; Labadi, Z.; Barsony, I.

    2009-08-01

    Al doped ZnO (ZAO) thin films (with Al-doping levels 2 at.%) were deposited at different deposition parameters on silicon substrate by reactive magnetron sputtering for solar cell contacts, and samples were investigated by transmission electron microscopy (TEM), electron energy loss spectroscopy (EELS) and spectroscopic ellipsometry (SE). Specific resistances were measured by the well known 4-pin method. Well visible columnar structure and in most cases voided other regions were observed at the grain boundaries by TEM. EELS measurements were carried out to characterize the grain boundaries, and the results show spacing voids between columnar grains at samples with high specific resistance, while no spacing voids were observed at highly conductive samples. SE measurements were evaluated by using the analytical expression suggested by Yoshikawa and Adachi [H. Yoshikawa, S. Adachi, Japanese Journal of Applied Physics 36 (1997) 6237], and the results show correlation between specific resistance and band gap energy and direct exciton strength parameter.

  12. Fabrication and Characterization of High-Crystalline Nanoporous ZnO Thin Films by Modified Thermal Evaporation System

    Science.gov (United States)

    Islam, M. S.; Hossain, M. F.; Razzak, S. M. A.; Haque, M. M.; Saha, D. K.

    2016-05-01

    The aim of this work is to fabricate high-crystalline nanoporous zinc oxide (ZnO) thin films by a modified thermal evaporation system. First, zinc thin films have been deposited on bare glass substrate by the modified thermal evaporation system with pressure of 0.05mbar, source-substrate distance of 3cm and source temperature 700∘C. Then, high-crystalline ZnO thin film is obtained by annealing at 500∘C for 2h in atmosphere. The prepared ZnO films are characterized with various deposition times of 10min and 20min. The structural property was investigated by X-ray diffractometer (XRD). The optical bandgap and absorbance/transmittance of these films are examined by ultraviolet/visible spectrophotometer. The surface morphological property has been observed by scanning electron microscope (SEM). ZnO films have showed uniform nanoporous surface with high-crystalline hexagonal wurtzite structure. The ZnO films prepared with 20min has excitation absorption-edge at 369nm, which is blueshifted with respect to the bulk absorption-edge appearing at 380nm. The gap energy of ZnO film is decreased from 3.14eV to 3.09eV with increase of the deposition time, which can enhance the excitation of ZnO films by the near visible light, and is suitable for the application of photocatalyst of waste water cleaning and polluted air purification.

  13. Realization of Ag-S codoped p-type ZnO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Tian Ning, E-mail: xtn9886@zju.edu.cn [Department of Science, Zhijiang College of Zhejiang University of Technology, Hangzhou, Zhejiang 310024 (China); Department of Physics, State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou, Zhejiang 310027 (China); Li, Xiang; Lu, Zhong [Department of Science, Zhijiang College of Zhejiang University of Technology, Hangzhou, Zhejiang 310024 (China); Chen, Yong Yue [Department of Physics, State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou, Zhejiang 310027 (China); Sui, Cheng Hua [Department of Science, Zhijiang College of Zhejiang University of Technology, Hangzhou, Zhejiang 310024 (China); Wu, Hui Zhen [Department of Physics, State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou, Zhejiang 310027 (China)

    2014-10-15

    Highlights: • Ag-S codoped p-type ZnO thin films have been fabricated. • The films exhibit low resistivity and high Hall mobility and hole concentration. • A ZnO:(Ag, S)/i-ZnO/ZnO:Al homojunction has been fabricated and shows rectifying behaviors. - Abstract: Ag-S codoped ZnO films have been grown on quartz substrates by e-beam evaporation at low temperature (100 °C). The effects of Ag{sub 2}S content on the structural and electrical properties of the films were investigated. The results showed that 2 wt% Ag{sub 2}S doped films exhibited p-type conduction, with a resistivity of 0.0347 Ω cm, a Hall mobility of 9.53 cm{sup 2} V{sup −1} s{sup −1}, and a hole concentration of 1.89 × 10{sup 19} cm{sup −3} at room temperature. The X-ray photoelectron spectroscopy measurements showed that Ag and S have been incorporated into the films. To further confirm the p-type conduction of Ag-S codoped ZnO films, a ZnO:(Ag, S)/i-ZnO/ZnO:Al homojunction was fabricated and rectifying behaviors of which was measured. High electrical performance and low growth temperature indicate that Ag{sub 2}S is a promising dopant to fabricate p-type Ag-S codoped ZnO films.

  14. Structure, morphology and electrical characterizations of direct current sputtered ZnO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Yang, L., E-mail: liu.yang@univ-littoral.fr [Univ Lille Nord de France, ULCO, UDSMM, 62228 Calais (France); Duponchel, B. [Univ Lille Nord de France, ULCO, UDSMM, 59140 Dunkerque (France); Cousin, R.; Gennequin, C. [Univ Lille Nord de France, ULCO, UCEIV, 59140 Dunkerque (France); Leroy, G.; Gest, J.; Carru, J.-C. [Univ Lille Nord de France, ULCO, UDSMM, 62228 Calais (France)

    2012-05-01

    ZnO thin films were deposited on glass substrates by direct current (DC) sputtering technique at room temperature (RT) to 400 Degree-Sign C with a 99.999% pure ZnO target. Then the samples deposited at RT were annealed in air from the RT to 400 Degree-Sign C. The effects of substrate temperature (T{sub s}) and annealing treatment (T{sub a}) on the crystallization behavior and the morphology have been studied by X-ray diffraction and atomic force microscopy. We also compared the structural properties of samples deposited at 400 Degree-Sign C on glass to those deposited on Pt/silicon substrate. The resistivity, surface roughness and size of the grains have also been studied and correlated to the thickness of ZnO films deposited on Pt/Si substrates. The experimental results reveal that the substrate has a major influence on the structural and morphological properties. For the films deposited on glass, below 400 Degree-Sign C, T{sub s} and T{sub a} have a similar influence on the structure of the films. Moreover, the ZnO samples deposited at RT and annealed in air have poor electrical properties.

  15. Investigation of chemical bath deposition of ZnO thin films using six different complexing agents

    Energy Technology Data Exchange (ETDEWEB)

    Khallaf, Hani; Chai, Guangyu; Lupan, Oleg; Heinrich, Helge; Park, Sanghoon; Schulte, Alfons; Chow, Lee, E-mail: chow@mail.ucf.ed [Department of Physics, University of Central Florida, Orlando, FL 32816 (United States)

    2009-07-07

    Chemical bath deposition of ZnO thin films using six different complexing agents, namely ammonia, hydrazine, ethanolamine, methylamine, triethanolamine and dimethylamine, is investigated. As-grown films were mainly ZnO{sub 2} with a band gap around 4.3 eV. Films annealed at 400 deg. C were identified as ZnO with a band gap around 3.3 eV. X-ray diffraction and micro-Raman spectroscopy revealed that as-grown films consist mainly of cubic zinc peroxide that was transformed into hexagonal ZnO after annealing. Rutherford backscattering spectroscopy (RBS) detected excess oxygen content in ZnO films after annealing. Fourier transform infrared spectroscopy of as-grown films showed a broad absorption band around 3300 cm{sup -1} suggesting that the as-grown films may consist of a mixture of zinc peroxide and zinc hydroxide. X-ray photoelectron spectroscopy multiplex spectra of the O 1s peak were found to be consistent with film stoichiometry revealed by RBS. High-resolution transmission electron micrographs showed small variations of the order of 10 nm in film thickness which corresponds to the average grain size. A carrier density as high as 2.24x10{sup 19} cm{sup -3} and a resistivity as low as 6.48 x 10{sup -1} OMEGA cm were obtained for films annealed at 500 deg. C in argon ambient.