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Defect Studies Of Single Crystal And Thin Film Zinc Oxide By Positron Annihilation Spectroscopy And Cathodoluminescence
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Book Synopsis Defect Studies of Single Crystal and Thin Film Zinc Oxide by Positron Annihilation Spectroscopy and Cathodoluminescence by : Chun-Kit To
Download or read book Defect Studies of Single Crystal and Thin Film Zinc Oxide by Positron Annihilation Spectroscopy and Cathodoluminescence written by Chun-Kit To and published by . This book was released on 2017-01-26 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Defect Studies of Single Crystal and Thin Film Zinc Oxide by Positron Annihilation Spectroscopy and Cathodoluminescence by : Chun-kit To
Download or read book Defect Studies of Single Crystal and Thin Film Zinc Oxide by Positron Annihilation Spectroscopy and Cathodoluminescence written by Chun-kit To and published by . This book was released on 2010 with total page 372 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Positron Annihilation Spectroscopic Studies of Undoped N-Type Zinc Oxide Single Crystal by : Chun-Wai Hui
Download or read book Positron Annihilation Spectroscopic Studies of Undoped N-Type Zinc Oxide Single Crystal written by Chun-Wai Hui and published by . This book was released on 2017-01-27 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation, "Positron Annihilation Spectroscopic Studies of Undoped N-type Zinc Oxide Single Crystal" by Chun-wai, Hui, 許俊偉, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. Abstract: Abstract of thesis entitled POSITRON ANNIHILATION SPECTROSCOPIC STUDIES OF UNDOPED N-TYPE ZINC OXIDE SINGLE CRYSTAL submitted by HUI CHUN WAI for the Degree of Master of Philosophy at The University of Hong Kong in August 2006 Positron lifetime spectroscopy and coincidence Doppler broadening spectroscopy (CDBS) were used to study the defects in two pieces of hydrothermal (HT) grown ZnO single crystal samples (HT1 and HT2) obtained from two different companies, namely University Wafer, US, and MaTecK, Germany. Single component model could offer good fitting to the lifetime spectra of HT1 and HT2 at temperatures ranging from 25K to 285K. The room temperature positron lifetimes of HT1 and HT2 were found to be 191ps and 181 ps, respectively. The observation was associated with saturated positron trapping into two different Zn-vacancy related defects existing in the two samples. For HT1, the lifetime was observed to be temperature independent. However for HT2, the lifetime had constant value with temperature higher than 200K. It then decreased with decreasing temperature and reached the value of 172ps at 30K. This temperature dependence of lifetime could be explained by the presence of an additional positron shallow trap. Positron-electron autocorrelation function (AF) was extracted from the CDBS spectra. The obtained AF mappings of HT1 and HT2 at room temperature confirmed that the defects existing in HT1 and HT2 should have different microstructures. Positron lifetime spectroscopy was also performed on undoped pressurized melted grown n-type ZnO single crystal. Two-component model was required to give good description to the lifetime spectra. The two lifetime components were found to have temperature independent values of 181ps and 366ps, which were attributed to saturated positron trapping into two defects, V related defect and vacancy cluster respectively. Zn DOI: 10.5353/th_b3857339 Subjects: Positron annihilation Zinc oxide Compound semiconductors - Spectra
Book Synopsis Zinc Oxide and Related Materials: Volume 957 by : Jürgen H. Christen
Download or read book Zinc Oxide and Related Materials: Volume 957 written by Jürgen H. Christen and published by . This book was released on 2007-04-05 with total page 470 pages. Available in PDF, EPUB and Kindle. Book excerpt: The MRS Symposium Proceeding series is an internationally recognised reference suitable for researchers and practitioners. The topics covered in this volume, first published in 2007, include devices, defects, spintronics and magnetism, growth, optical properties and nanostructures, and doping and processing TFTs.
Book Synopsis Defect Study of Zinc Oxide Bulk Materials by Positron Lifetime Spectroscopy by : 蘇振強
Download or read book Defect Study of Zinc Oxide Bulk Materials by Positron Lifetime Spectroscopy written by 蘇振強 and published by . This book was released on 2017-01-27 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation, "Defect Study of Zinc Oxide Bulk Materials by Positron Lifetime Spectroscopy" by 蘇振強, Chun-keung, So, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. Abstract: Abstract of thesis entitled DEFECT STUDY OF ZINC OXIDE BULK MATERIALS BY POSITRON LIFETIME SPECTROSCOPY submitted by So Chun Keung for the Degree of Master of Philosophy at The University of Hong Kong in January 2008 Vacancy type defects in ZnO bulk materials grown by different methods from various companies were studied by positron lifetime spectroscopy. Hydrothermal grown ZnO samples from University Wafers Company contained a single 193 ps positron lifetime component, attributed to a zinc vacancy related defect. Upon electron irradiation, a single 185 ps positron lifetime was identified which was explained by the formation of another zinc vacancy related defect. This defect remained stable after isochronal annealing of the sample up to 1200C. Samples from the same company but of different batches contained a 180 ps single lifetime component. In addition, hydrothermal grown ZnO single crystals from Altramet Company and MaTecK Company also demonstrated the 180 ps single lifetime component. Two batches of ZnO single crystals grown by pressurized melt grown method from Cermet company were studied. Data analyses on the older batch samples revealed 1the existence of a 257 ps lifetime component, tentatively attributed to Zn+O divacancy defect. This defect was not detected in more recently grown samples. Instead, a 166 ps single component was found, of which the nature of it could not be unambiguously determined. Vapour phase grown as-grown and 900C annealed ZnO samples were studied. Single lifetime component of 175 ps was identified. Nevertheless, the exact nature of it required further investigation. In the present study, positron lifetimes in different ZnO samples were found. The kinds of open volume vacancy-type defects were believed to be dependent on the growing methods. In addition, production of ZnO single crystals with high and consistent qualities was yet to be achieved at present. 2 DOI: 10.5353/th_b3955869 Subjects: Zinc oxide Materials - Defects Positrons - Spectra
Book Synopsis DEFECTS AND OPTOELECTRONIC PROPERTIES OF ZINC OXIDE by : Naresh Adhikari
Download or read book DEFECTS AND OPTOELECTRONIC PROPERTIES OF ZINC OXIDE written by Naresh Adhikari and published by . This book was released on 2019 with total page 53 pages. Available in PDF, EPUB and Kindle. Book excerpt: Zinc oxide (ZnO) is a compound semiconductor with a direct wide band gap of 3.4 eV with a high exciton binding energy of 60 meV at room temperature. It is a widely investigated semiconductor due to its high potential for optoelectronic applications in the UV region, especially, for light-emitting diodes and lasers. In these applications of ZnO, native point defects play key roles. The understanding of these defects will help us to realize and control the performance of ZnO in these applications. Also, it will help us to realize p-type doping in ZnO, which will open a way for oxide semiconductor based bipolar devices. Due to the reproducibility of high-quality ZnO crystals and their interesting properties, it is preferred for extensive research over other wide band gap semiconductors. So far, as research points out, native point defects are not well understood. In our work, we will present electrical and optical characterization studies done on ZnO single crystals as well as on polycrystals, and we will relate these measurements to defect studies using Positron Annihilation Lifetime Spectroscopy (PALS) and Coincident Doppler Broadening Spectroscopy (CDBS). It was found that the increase in well-known green luminescence is associated with a decrease in conductivity and charge carrier concentration. Positron lifetime spectroscopy measurements were carried out to reveal the origin of defects responsible for decreasing the conductivity and enhancing the green luminescence. Lastly, it was interesting to observe the decrease in the ratio between green luminescence to near band emission as the laser power increased.
Book Synopsis Positron Annihilation Spectroscopic Studies of Undoped N-type Zinc Oxide Single Crystal by : Chun-wai Hui
Download or read book Positron Annihilation Spectroscopic Studies of Undoped N-type Zinc Oxide Single Crystal written by Chun-wai Hui and published by . This book was released on 2006 with total page 136 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Studies of Oxygen Implantation Induced Deep Level Defects in Zinc Oxide Single Crystal by : Ziran Ye
Download or read book Studies of Oxygen Implantation Induced Deep Level Defects in Zinc Oxide Single Crystal written by Ziran Ye and published by . This book was released on 2017-01-26 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation, "Studies of Oxygen Implantation Induced Deep Level Defects in Zinc Oxide Single Crystal" by Ziran, Ye, 叶自然, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. Abstract: Zinc Oxide (ZnO)is a wide band gap semiconductor which has attracted great attention because of its wide applicability. In order to obtain semiconductor devices with stable and reproducible properties further study of deep level defects is essential. DLTS (Deep level Transient Spectroscopy) is a direct and straightforward techniqueto determine the energy level of the deep level defects. Other information such as activation energy and capture cross section of the defect can also be obtained through this method. In our study ZnO single crystal samples were implanted by oxygen with the energy of 150keV. After the pretreatment of hydrogen peroxide, Schottky contacts were fabricated with Au film deposited by thermal evaporation. Deep level defects were studied by deep level transient spectroscopy (DLTS). Single peak spectra were observed in the as-implanted sample and samples anneal at 350oC, 650oC and 750oC with the corresponding activation energy decreasing with the annealing temperature from 0.29eV as found in theas-implanted sample. Three peaks were identified in the DLTS spectra of the 900oC sample, with the activation energies of 0.11eV, 0.16eV and 0.37eV respectively.After analysis in detail we found some peaks in the DLTS spectra were the combination of two other peaks, dominated in different temperature range. The thermal evolutions of the deep levels up to the temperature of 1200oC were also investigated. DOI: 10.5353/th_b4715385 Subjects: Zinc oxide - Defects Deep level transient spectroscopy Ion implantation
Book Synopsis Studies of Surface States in Zinc Oxide Nanopowders by : Raul Mugabe Peters
Download or read book Studies of Surface States in Zinc Oxide Nanopowders written by Raul Mugabe Peters and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The surface of ZnO semiconductor nanosystems is a key performance-defining factor in numerous applications. In this work we present experimental results for the surface defect-related properties of ZnO nanoscale systems. Surface photovoltage spectroscopy was used to determine the defect level energies within the band gap, the conduction vs. valence band nature of the defect-related transitions, and to probe key dynamic parameters of the surface on a number of commercially available ZnO nanopowders. In our experimental setup, surface photovoltage characterization is conducted in high vacuum in tandem with in situ oxygen remote plasma treatments. Surface photovoltage investigations of the as-received and plasma-processed samples revealed a number of common spectral features related to surface states. Furthermore, we observed significant plasma-induced changes in the surface defect properties. Ex situ positron annihilation and photoluminescence measurements were performed on the studied samples and correlated with surface photovoltage results. The average positron lifetimes were found to be substantially longer than in a bulk single crystalline sample, which is consistent with the model of grains with defect-rich surface and subsurface layers. Compression of the powders into pellets yielded reduction of the average positron lifetimes. Surface photovoltage, positron annihilation, and photoluminescence spectra consistently showed sample-to-sample differences due to the variation in the overall quality of the nanopowders, which partially obscures observation of the scaling effects. However, the results demonstrated that our approach is efficient in detecting specific surface states in nanoscale ZnO specimens and in elucidating their nature.
Book Synopsis DEFECTS AND FERROMAGNETISM IN TRANSITION METAL DOPED ZINC OXIDE by : Sunil Thapa
Download or read book DEFECTS AND FERROMAGNETISM IN TRANSITION METAL DOPED ZINC OXIDE written by Sunil Thapa and published by . This book was released on 2016 with total page 56 pages. Available in PDF, EPUB and Kindle. Book excerpt: Transition metal doped zinc oxide has been studied recently due to its potential application in spintronic devices. The magnetic semiconductor, often called Diluted Magnetic Semiconductors (DMS), has the ability to incorporate both charge and spin into a single formalism. Despite a large number of studies on ferromagnetism in ZnO based DMS and the realization of its room temperature ferromagnetism, there is still a debate about the origin of the ferromagnetism. In this work, the synthesis and characterization of transition metal doped zinc oxide have been carried out. The sol-gel method was used to synthesize thin films, and they were subsequently annealed in air. Characterization of doped zinc oxide films was carried out using the UV-visible range spectrometer, scanning electron microscopy, superconducting quantum interference device (SQUID), x-ray diffraction(XRD) and positron annihilation spectroscopy. Hysteresis loops were obtained for copper and manganese doped zinc oxide, but a reversed hysteresis loop was observed for 2% Al 3% Co doped zinc oxide. The reversed hysteresis loop has been explained using a two-layer model.
Book Synopsis Deep Level Defects Study of Arsenic Implanted Zno Single Crystal by : Congyong Zhu
Download or read book Deep Level Defects Study of Arsenic Implanted Zno Single Crystal written by Congyong Zhu and published by Open Dissertation Press. This book was released on 2017-01-27 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation, "Deep Level Defects Study of Arsenic Implanted ZnO Single Crystal" by Congyong, Zhu, 朱從佣, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. DOI: 10.5353/th_b4098775 Subjects: Zinc oxide Arsenic Doped semiconductors Semiconductors - Defects Deep level transient spectroscopy
Book Synopsis Deep Level Transient Spectroscopic Study of Intrinsic Defects in Particle-Irradiated Zno Single Crystal Materials by : Xiaohong Lu
Download or read book Deep Level Transient Spectroscopic Study of Intrinsic Defects in Particle-Irradiated Zno Single Crystal Materials written by Xiaohong Lu and published by Open Dissertation Press. This book was released on 2017-01-26 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation, "Deep Level Transient Spectroscopic Study of Intrinsic Defects in Particle-irradiated ZnO Single Crystal Materials" by Xiaohong, Lu, 吕小红, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. Abstract: Zinc oxide (ZnO), as a Ⅱ-Ⅵ compound semiconductor with a wide direct band gap, has attracted great attention from the worldwide researchers for its potential application in the fields of spintronics and optoelectronics. At present research about the defects in ZnO and ZnO-based materials is still far from complete. The deep level defects in melted grown ZnO single crystal induced by helium ions implantation and electron irradiation, as well as their thermal evolution, were studied in this research using the technique of deep level transient spectroscopy (DLTS) and photoluminescence (PL). DLTS results indicated that, besides E3 ( 0.28 ) trap which was widely observed in the as-grown ZnO samples, the deep level with 0.92 was also indentified in the helium-implanted ZnO samples, which was introduced by the ion implantation and tentatively assigned to be the oxygen vacancy (VO). This deep level was removed after 350 oC annealing in argon gas. Annealing at 350 oC also brought along a new deep level with 0.66 into helium-implanted samples which could be annealed out by 650 oC annealing in argon gas. The electron irradiation induced a deep level with 0.59 into ZnO, which was probably associated with the singly charged state of VO. This deep level also tended to be removed at 350 oC annealing in argon gas. The PL spectra revealed that both helium implantation and electron irradiation could improve the bound-exciton peak. Helium implantation also introduced defects emission at 1.90 eV, which was the red luminescence band, into the ZnO single crystal materials. This red luminescence band peak might be associated with DAP recombination. Electron irradiation might restrain the green luminescence in ZnO single crystal. The fine structures could disappear as the measurement temperature increased, leaving the green luminescence band only. DOI: 10.5353/th_b4786991 Subjects: Zinc oxide - Defects Deep level transient spectroscopy
Download or read book Chemical Abstracts written by and published by . This book was released on 1991 with total page 2682 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Characterization of Single Defects in Zinc Oxide by : Yun-Yi Pai
Download or read book Characterization of Single Defects in Zinc Oxide written by Yun-Yi Pai and published by . This book was released on 2014 with total page 68 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis summarizes my work on characterizing isolated defects in zinc oxide (ZnO). In chapter 1, I will briefly review the major strength of quantum information processing over classical computation. I will then review the basic properties of nitrogen-vacancy centers, the most-studied point defect species in diamond, and how they motivate the search for defects of similar properties in other semiconductor materials for defect-based quantum information processing. In chapter 2, I will describe our initial study on the optical properties of successfully isolated defects in ZnO: their fluorescence spectra, excited state lifetimes, and their photodynamics including blinking. In chapter 3, I will detail my work on extending the capability of an atomic force microscope to include simultaneous imaging in a confocal geometry. In chapter 4, I will discuss possible directions for our defect studies.
Book Synopsis Space Charge Spectroscopy Applied to Defect Studies in Ion-Implanted Zinc Oxide Thin Films by : Matthias Schmidt
Download or read book Space Charge Spectroscopy Applied to Defect Studies in Ion-Implanted Zinc Oxide Thin Films written by Matthias Schmidt and published by . This book was released on 2012 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Diffusion and Defects in ZnO by : David Fisher
Download or read book Diffusion and Defects in ZnO written by David Fisher and published by . This book was released on 2013 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Lanthanum hexaboride is useful because it possesses a high melting point (2210C), a low work function, one of the highest known electron emissivities, and is stable in vacuum. This volume summarises the extant data on the properties of this material, including the: bulk modulus, conductivity, crystal structure, Debye temperature, defect structure, elastic constants, electronic structure, emissivity, Fermi surface, hardness, heat capacity, magnetoresistance, reflectivity, resistivity, specific heat, surface structure, thermal conductivity, thermoelectric power, toughness and work function. The issue also includes original research papers on: the Pitting Resistance of 316 Stainless Steel in Ringer's Solution, the Effect of Different Modifiers on the Microstructure and Strength of Locally Developed A356 Al-Si Alloy, the Site Preference of Zr in NiAl Dislocation Cores and its Effects on Bond Character, the Effect of Different Combinations of Salt Modifier on the Mechanical Properties and Microstructure of A356 Al-Si Alloy, Quasicrystalline Phase Formation in High Frequency Induction Melted Al80Cu14Fe6 Alloy, Numerical Investigation of the Effect of Sprue Base Design on the Flow Pattern of Aluminum Gravity Castings, the Evaluation of Surface Preparation Techniques for Steel Substrates Prior to Coating, Thermal Desorption of Hydrogen from AISI 316L Stainless Steel and Pure Nickel, Structural and Concentration Heterogeneities during the Formation of Silicide Phases in the Ti(5nm)/Ni(24nm)/Si(001)Thin-Film System, Studies of the g-Factor and Hyperfine Structure Constant for Ir4+ in CdO, Theoretical Studies of the Local Structures and Spin Hamiltonian Parameters for the Cu2+ Centers in Alkali Barium Borate Glasses, Study of the Properties of CR-39 Polymer Irradiated with Alpha Particles, Review of Diffusion and Interfacial Reactions in Sandwich Thin-Film Couples and the Correlation Coefficient between Vickers Hardness and Nuclear Techniques.
Book Synopsis Comparative Study on Chemical Properties of Zinc Oxide Single Crystal Surfaces with and Without Defects by : Wu-Hsun Cheng
Download or read book Comparative Study on Chemical Properties of Zinc Oxide Single Crystal Surfaces with and Without Defects written by Wu-Hsun Cheng and published by . This book was released on 1982 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
