Dopants and Transport Properties of Transparent Conducting Zinc Oxide Thin Films PDF Download

Author: Joel N. Duenow
Publisher:
ISBN:
Category : Electron transport
Languages : en
Pages : 204

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Author: Klaus Ellmer
Publisher: Springer Science & Business Media
ISBN: 3540736123
Category : Science
Languages : en
Pages : 453

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Zinc oxide (ZnO) belongs to the class of transparent conducting oxides that can be used as transparent electrodes in electronic devices or heated windows. In this book the material properties of, the deposition technologies for, and applications of zinc oxide in thin film solar cells are described in a comprehensive manner. Structural, morphological, optical and electronic properties of ZnO are treated in this review.

Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Transparent conducting oxides were successfully prepared from mixed zinc nitrate hexahydrate and indium nitrate hydrate solutions in ethylene glycol using sol-gel technique. The In content in the film was varied (0, 2, 10, 20, 40, 75 and 100 atom %). Films were prepared by spin coating of the liquid precursors followed by thermal decomposition at 400° C after each layer. According to X-ray diffraction (XRD) measurements, the pure ZnO and pure InO films (0 and at 100 % In) were crystalline as-deposited. The crystallinity was suppressed in mixed compositions such that the films with compositions between 10 and 75 at % were amorphous. All the films were transparent with the transmission cut-off frequency near 400 nm, which is characteristic of TCO materials. All as-deposited films were conductive with 0 and 100 atom % In having the lowest resistivities. The resistivity of all compositions were improved by post-deposition reducing anneal in pure Ar at 300° C. The lowest resistivity of 0.2?cm was obtained for the pure ZnO after Ar anneal. It was two-orders of magnitude higher than reported in the literature for the In-doped ZnO, which was attributed to the low processing temperature. The resistivities of as-deposited and annealed in Ar films were increased by consequent air anneal at 300° C.

Author: Bhawana Joshi
Publisher:
ISBN: 9783659527166
Category :
Languages : en
Pages : 196

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Author: Chennupati Jagadish
Publisher: Elsevier
ISBN: 0080464033
Category : Science
Languages : en
Pages : 600

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With an in-depth exploration of the following topics, this book covers the broad uses of zinc oxide within the fields of materials science and engineering: - Recent advances in bulk , thin film and nanowire growth of ZnO (including MBE, MOCVD and PLD), - The characterization of the resulting material (including the related ternary systems ZgMgO and ZnCdO), - Improvements in device processing modules (including ion implantation for doping and isolation ,Ohmic and Schottky contacts , wet and dry etching), - The role of impurities and defects on materials properties - Applications of ZnO in UV light emitters/detectors, gas, biological and chemical-sensing, transparent electronics, spintronics and thin film

Author: Klaus Ellmer
Publisher: Springer
ISBN: 9783540840961
Category : Technology & Engineering
Languages : en
Pages : 446

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Book Description
Zinc oxide (ZnO) belongs to the class of transparent conducting oxides that can be used as transparent electrodes in electronic devices or heated windows. In this book the material properties of, the deposition technologies for, and applications of zinc oxide in thin film solar cells are described in a comprehensive manner. Structural, morphological, optical and electronic properties of ZnO are treated in this review.

Author: Michael John Campion
Publisher:
ISBN:
Category :
Languages : en
Pages : 141

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Book Description
Transparent conductors play important roles in many optoelectronic devices such as LEDs, thin film solar cells, and smart windows through their ability to efficiently transport both photons and electrons. Simultaneous requirements of a wide band gap, high free carrier concentration, and high electron mobility limits the selection of available transparent conductor materials. Further improvements in the optical and electrical properties, along with improvements in processing tolerance, are highly desirable for this material class. One key limitation of current transparent conducting oxides is their response to oxidation, which can cause severe decreases to the conductivity of the material through ionic compensation. Materials with slow oxygen kinetics or resistance to the formation of compensating ionic defects could lead to more flexible operating and processing conditions for applications requiring transparent conductors. The properties of transparent conducting oxides, Al-doped ZnO and La-doped BaSnO3, were examined through a variety of methods with a focus on the impact of processing on the free carrier concentration, electron transport, and optical properties. Al-doped ZnO was examined as a well-known alternative to indium tin oxide (ITO) that has been shown to be limited by relatively narrow processing conditions and large variances in reported properties. BaSnO3 is a comparatively new material in the field of transparent conductors, attractive mainly due to its exceptionally high electron mobility for an oxide. Little is currently known about the nature of defects and processing on the optical and electrical properties of this material, but this information will be important to understand before implementing this material in practical devices. For these materials, I examined the roles of oxygen stoichiometry and point defect formation in impacting properties and stability under both processing conditions and harsh operating conditions and explored the limitations and opportunities provided by these transparent conducting oxide systems. Al-doped ZnO thin films were produced by pulsed laser deposition under a variety of oxygen conditions demonstrating the strong dependence of free electron concentration and mobility on the oxidation state of the material. The free carrier absorption in the infrared photon range was measured and modeled and found to agree well with theory assuming ionized impurity scattering as the limiting electron scattering mechanism. These effects were understood through the framework of the formation of compensating zinc vacancies under oxidizing conditions, leading to decreases in the free electron concentration. Atom probe tomography was applied to Al-doped ZnO thin films deposited on Si substrates, demonstrating an effective accumulation of Al near the ZnO/Si interface, but with no detected precipitation or agglomeration in the x-y plane of the film, even for heavily doped films. This was surprising due to the high concentration of Al-dopant in the material, exceeding the thermodynamic solubility limit of bulk ZnO. An accumulation of Al-dopant was observed at the ZnO/Si interface under multiple conditions, with the oxygen atmosphere during deposition and nature of the Si substrate affecting the degree of accumulation. Because transparent conductors are typically used to transfer charge through interfaces, understanding the nature and implications of this observed accumulation effect could be essential to understanding device performance. La-doped and undoped BaSnO3 thin films and bulk samples were tested for their electrical conductivity in-situ under various temperatures and oxygen partial pressures. In the undoped case, a p-type to n-type transition was observed at lower temperatures with decreasing oxygen partial pressure, with the behavior correlated to the formation and annihilation of oxygen and cation vacancies. Under donor-doping, a measurable, but weak n-type dependence of conductivity was demonstrated, pointing to a surprisingly weak role played by cation vacancy charge compensation over the measured temperature ranges. Compared to other similar oxide systems, compensation by cation vacancies would normally be expected to be strong under oxidizing conditions. This is a key advantage for La-doped BaSnO3 as a high temperature oxygen stable material compared to other competing materials that are more susceptible to conductivity degradation due to ionic compensation of the donor dopant under oxidizing conditions. This was directly demonstrated in the testing of the conductivity response of La-doped BaSnO3 thin films that maintained high conductivity under a large range of oxygen and temperature conditions. Oxygen diffusion in the material was estimated from conductivity relaxation and further explored with oxygen tracer diffusion studies. These studies revealed an activation energy of 2 eV for the oxygen diffusion process, as well as a depth dependent diffusivity leading to depressed oxygen diffusivities near the surface. Study of epitaxial and polycrystalline thin films of La-doped BaSnO3 revealed a difference in the rate of oxidation response of the conductivity. Epitaxial thin films exhibited a weak power law dependence on temperature while polycrystalline thin films under oxidizing conditions exhibited an activation energy of 0.36 eV. This effect was attributed to the formation of narrow space charge regions at the grain boundaries under oxidizing conditions. Simultaneous measurements of the infrared transmission and electrical conductivity of thin films were performed as a means of correlating infrared transmission with conductivity at high temperatures under various controlled atmospheres. These two measurements were found to be strongly correlated and were demonstrated to be connected to the formation and annihilation of free carriers in the thin films. A novel measurement technique was explored in which the conductance response was measured across a substrate during pulsed laser deposition of Al-doped ZnO. The measured conductance profile as a function of time was correlated to the expected growth regimes typical of an island growth mode, and the thickness dependence of resistivity was directly observed. Additional information about the growth conditions was obtained through conductance relaxation after single pulses, performed under different growth chamber atmospheres.

Author: Vinod Kumar
Publisher: LAP Lambert Academic Publishing
ISBN: 9783838325347
Category :
Languages : en
Pages : 156

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Book Description
Transparent Conducting Oxides (TCOs) are unusual materials as they have to possess a high electrical conductivity with good transparency in the visible region of electromagnetic spectrum. TCOs have many applica-tions such as electrical inter-connections for window electrodes in flat panel displays, electro-optical devices and solar cells. TCOs are also receiving much attention and recognition as they are promising candidate for optoelectronic application in the ultraviolet to visible range. Other important parameters that determine the usefulness of TCOs are environmental stability, process-ing compatibility with other device elements and production cost etc. Indium (In) doped tin oxide also known as ITO is used as TCO in industries. Now a days, TCOs have already been largely investigated. Therefore, in the recent years, this has stimulated the development of new TCO materials like doped ZnO."

Author: David Levy
Publisher: John Wiley & Sons
ISBN: 3527342079
Category : Technology & Engineering
Languages : en
Pages : 390

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Book Description
Edited by well-known pioneers in the field, this handbook and ready reference provides a comprehensive overview of transparent conductive materials with a strong application focus. Following an introduction to the materials and recent developments, subsequent chapters discuss the synthesis and characterization as well as the deposition techniques that are commonly used for energy harvesting and light emitting applications. Finally, the book concludes with a look at future technological advances. All-encompassing and up-to-date, this interdisciplinary text runs the gamut from chemistry and materials science to engineering, from academia to industry, and from fundamental challenges to readily available applications.

Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 98

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