Download or read book Characterizations of As doped ZnO Films Grown on Si Substrates by Atmospheric Pressure Metal organic Chemical Vapor Deposition written by 王凱正 and published by . This book was released on 2010 with total page 136 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Metalorganic Vapor Phase Epitaxy MOVPE written by Stuart Irvine and published by John Wiley & Sons. This book was released on 2019-08-27 with total page 584 pages. Available in PDF, EPUB and Kindle. Book excerpt: Systematically discusses the growth method, material properties, and applications for key semiconductor materials MOVPE is a chemical vapor deposition technique that produces single or polycrystalline thin films. As one of the key epitaxial growth technologies, it produces layers that form the basis of many optoelectronic components including mobile phone components (GaAs), semiconductor lasers and LEDs (III-Vs, nitrides), optical communications (oxides), infrared detectors, photovoltaics (II-IV materials), etc. Featuring contributions by an international group of academics and industrialists, this book looks at the fundamentals of MOVPE and the key areas of equipment/safety, precursor chemicals, and growth monitoring. It covers the most important materials from III-V and II-VI compounds to quantum dots and nanowires, including sulfides and selenides and oxides/ceramics. Sections in every chapter of Metalorganic Vapor Phase Epitaxy (MOVPE): Growth, Materials Properties and Applications cover the growth of the particular materials system, the properties of the resultant material, and its applications. The book offers information on arsenides, phosphides, and antimonides; nitrides; lattice-mismatched growth; CdTe, MCT (mercury cadmium telluride); ZnO and related materials; equipment and safety; and more. It also offers a chapter that looks at the future of the technique. Covers, in order, the growth method, material properties, and applications for each material Includes chapters on the fundamentals of MOVPE and the key areas of equipment/safety, precursor chemicals, and growth monitoring Looks at important materials such as III-V and II-VI compounds, quantum dots, and nanowires Provides topical and wide-ranging coverage from well-known authors in the field Part of the Materials for Electronic and Optoelectronic Applications series Metalorganic Vapor Phase Epitaxy (MOVPE): Growth, Materials Properties and Applications is an excellent book for graduate students, researchers in academia and industry, as well as specialist courses at undergraduate/postgraduate level in the area of epitaxial growth (MOVPE/ MOCVD/ MBE).

Download or read book Characteristics of ZnO Nanorods Grown by Atmospheric Pressure Metal organic Chemical Vapor Deposition written by 謝欣宜 and published by . This book was released on 2010 with total page 130 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Growth and Characterization of Epitaxial ZnO Thin Films on GaN 0001 Epilayers and ZnO 0001 Substrates Using Metalorganic Chemical Vapor Depositon written by and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: ZnO thin films were produced on GaN(0001) epilayers and ZnO(0001) substrates utilizing an iterative process requiring a structured low temperature (480 & deg;C) layer followed by a high temperature (800 & deg;C) densification step to create approximately 200 nm of contiguous film. This process is subsequently repeated to achieve thicker films with each iteration producing approximately 200 nm of dense film. Diethylzinc was used as the zinc source, UHP oxygen (O2) as the oxygen source, and UHP argon as both the carrier and diluent gas. Nitrous (N2O) and nitric oxide (NO2) were also used both as potential oxygen sources in the pure state as well as mixed with oxygen in the chamber and for nitrogen doping of the growing film. Major impurities of C, H, and N were incorporated into the films with the majority of the incorporation occurring during the low temperature step. Films grown using N2O + O2 contained an average of 5 x 1017 cm-3 atomic nitrogen while films using NO2 + O2 had an average nitrogen concentrations of 9 x 1019 cm-3. Needle microstructures were observed for low temperature layers using O2 and N2O + O2, while networked structures formed when using NO2 + O2. The surface of the densified films contained hexagonal pits that increased in number and depth with an increase in film thickness. Triple-axis XRD measurements indicated that the crystal structure of the films mimic the underlying substrates. A comparative analysis of undoped and N-doped films using capacitance voltage and photoluminescence measurements showed that the N-doped films were more insulating than the undoped films and the incorporation of nitrogen decreases the amount of excitonic peaks observed in the PL spectra. The 3.367 eV ionized donor bound exciton becomes dominant in N-doped films relative to the 3.361 eV donor bound exciton that dominates the undoped films. A preliminary inductively coupled plasma etching study determined that the smoothest sidewalls and surfaces were obtained using an.

Download or read book Growth and Characterization of Zno Nanostructures written by Abdul Samad Syed and published by LAP Lambert Academic Publishing. This book was released on 2012-08 with total page 84 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fabrication of efficient Ultraviolet Light Emitting Diodes (UV LEDs) is a challenging task for the semiconductor industry of the modern times. Finding the suitable semiconducting material is the key in order to make efficient LEDs. This book aims at understanding the use of ZnO in UV LEDs that demands the understanding of its optical properties first. Structural and optical properties of any semiconducting material are strongly correlated. An adequate knowledge and understanding of this relationship is necessary for fabrication of devices with desired optical properties. The aim of this work was to investigate the change in optical properties caused by growth techniques and substrate modification. To study the influence of growth technique on optical properties, ZnO nanostructures were grown using atmospheric pressure metal organic chemical vapor deposition (APMOCVD) and chemical bath deposition (CBD) techniques. Off-cut angle of SiC substrates were modified to observe the change on the optical properties. The results that are obtained demonstrate a significant contribution in the fields of ZnO based nano-optoelectronics and nano-electronics.

Download or read book Electrical Electronics Abstracts written by and published by . This book was released on 1997 with total page 1860 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Processing and Characterization of P Type Doped Zinc Oxide Thin Films written by Michelle Anne Myers and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Applications of zinc oxide (ZnO) for optoelectronic devices, including light emitting diodes, semiconductor lasers, and solar cells have not yet been realized due to the lack of high-quality p-type ZnO. In the research presented herein, pulsed laser deposition is employed to grow Ag-doped ZnO thin films, which are characterized in an attempt to understand the ability of Ag to act as a p-type dopant. By correlating the effects of the substrate temperature, oxygen pressure, and laser energy on the electrical and microstructural properties of Ag-doped ZnO films grown on c-cut sapphire substrates, p-type conductivity is achieved under elevated substrate temperatures. Characteristic stacking fault features have been continuously observed by transmission electron microscopy in all of the p-type films. Photoluminescence studies on n-type and p-type Ag-doped ZnO thin films demonstrate the role of stacking faults in determining the conductivity of the films. Exciton emission attributed to basal plane stacking faults suggests that the acceptor impurities are localized nearby the stacking faults in the n-type films. The photoluminescence investigation provides a correlation between microstructural characteristics and electrical properties of Ag- doped ZnO thin films; a link that enables further understanding of the doping nature of Ag impurities in ZnO. Under optimized deposition conditions, various substrates are investigated as potential candidates for ZnO thin film growth, including r -cut sapphire, quartz, and amorphous glass. Electrical results indicated that despite narrow conditions for obtaining p-type conductivity at a given substrate temperature, flexibility in substrate choice enables improved electrical properties. In parallel, N+-ion implantation at elevated temperatures is explored as an alternative approach to achieve p-type ZnO. The ion implantation fluence and temperature have been optimized to achieve p-type conductivity. Transmission electron microscopy reveals that characteristic stacking fault features are present throughout the p-type films, however in n-type N-doped films high-density defect clusters are observed. These results suggest that the temperature under which ion implantation is performed plays a critical role in determining the amount of dynamic defect re- combination that can take place, as well as defect cluster formation processes. Ion implantation at elevated temperatures is shown to be an effective method to introduce increased concentrations of p-type N dopants while reducing the amount of stable post-implantation disorder. Finally, the fabrication and properties of p-type Ag-doped ZnO/n-type ZnO and p-type N-doped ZnO/n-type ZnO thin film junctions were reported. For the N-doped sample, a rectifying behavior was observed in the I-V curve, consistent with N-doped ZnO being p-type and forming a p-n junction. The turn-on voltage of the device was -2.3 V under forward bias. The Ag-doped samples did not result in rectifying behavior as a result of conversion of the p-type layer to n-type behavior under the n- type layer deposition conditions. The systematic studies in this dissertation provide possible routes to grow p-type Ag-doped ZnO films and in-situ thermal activation of N-implanted dopant ions, to overcome the growth temperature limits, and to push one step closer to the future integration of ZnO-based devices. The electronic version of this dissertation is accessible from http://hdl.handle.net/1969.1/149354

Download or read book Journal of the Physical Society of Japan written by and published by . This book was released on 1995 with total page 1464 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Japanese Journal of Applied Physics written by and published by . This book was released on 2007 with total page 1036 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book International Aerospace Abstracts written by and published by . This book was released on 1999 with total page 974 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Electrical Characterization of ZnO thin films grown by molecular beam epitaxy written by Vladimir Petukhov and published by Cuvillier Verlag. This book was released on 2012-04-25 with total page 112 pages. Available in PDF, EPUB and Kindle. Book excerpt: For the electronic and optoelectronic device realization a precise control of the electrical properties in the utilized material is a very important issue. Doping profiles in realized p-njunctions influence the functionality of the devices. The morphological and crystal properties of a device material directly influence the electrical ones. Dislocations present in a region of p-n-junctions can short circuit them leading to malfunctions. Too rough surfaces during epitaxial growth could lead to inhomogeneities in a single or multiple quantum wells and superlattices. The main goal of the present work was to provide the basis for a reliable p-type doping of ZnO grown by molecular beam epitaxy. Firstly, the well established heteroepitaxial growth on c-sapphire substrates has been employed. Based on the theoretical and experimental works, suggesting nitrogen to be the impurity that builds the most shallow acceptor level in ZnO comparing to other group-V elements, it has been implied as a dopant. To generate reactive nitrogen atoms an rf-plasma source has been utilized in the MBE process. The resulting samples have been characterized by such methods as AFM, XRD, TEM, PL spectroscopy, temperature domain Hall measurements (TDHM) and ECV-profiling. First results of TDHM have shown that even in undoped samples the temperature dependencies of the electron mobility and carrier concentration have regions which are difficult to interpret. It is necessary to fit them with theoretical curves in order to extract the correct values. This task has proven to be very difficult. The complicated character of the dependencies has been explained in terms of the multilayer conduction model dividing a layer in thin interfacial region with mobility and carrier concentration μ1 and n1 respectivly and bulk region with a higher mobility μ2 and lower carrier concentration n2. The electrical transport in the bulk region has been modeled in terms of the general scattering theory in polar semiconductors. Such scattering mechanisms as scattering on polar-optical phonons, piezoelectric phonons, acoustic deformation potential, strain induced fields, dislocations, ionized and neutral impurities have been taken into account. Two cases have been considered to model transport in the interfacial region: 1) transport takes place in the conduction band of a highly doped degenerate semiconductor; 2) transport takes place in the impurity band formed by intermediate concentration of impurities and in conduction band in parallel. In the second case transport at the interface in conduction band has been neglected in the region of the low temperatures due to the impurities freeze-out and carrier concentration has been taken temperature independent like in the first case. To investigate experimentally the transport character in these two regions independently a mobility-spectrum analysis has been conducted. Theoretical results utilizing the two models have been compared with experimentally extracted mobility and carrier concentration in the interfacial region. It has been concluded that the concentration of donors in the layers is not high enough for the impurity band to merge with the conduction band and the second model is more consistent. The theoretically acquired donor concentration profiles have been compared with ECV-profiles. The agreement is very good. Simulations have revealed a shallow donor state with the ionization energy of approximately 45 meV . In the literature, this donor state in ZnO is attributed to hydrogen. However, due to the high diffusion mobility of hydrogen in ZnO, an annealing process would obviously decrease the carrier concentration in the samples which has not been the case. It has been suggested that the main donor centers are the electrically active crystal point defects generated by dislocations. Layers doped with nitrogen have been grown at very low temperatures (≈ 200°C) and at temperatures ranging from 400°C to 500°C, which are optimal for the epitaxial growth of ZnO. The samples grown at low temperatures are single crystalline with mosaic structure. In both cases, the introduction of the dopant increased the carrier concentration. This has been accounted for a bad crystal quality resulting in the inhomogeneous incorporation of nitrogen and for high background donor concentration due to the high dislocations densities. Additionally, the incorporation of acceptor centers shifts the Fermi-level increasing the formation probability of the compensating point defects. The analysis of TDHM showed an inconsistency of the one donor level model in the case of nitrogen doped samples. This fact and the decrease in the carrier concentration after annealing at 800°C for 30 minutes in ambient air can be explained by nitrogen forming donor-like defect complexes. In an attempt to improve the crystal quality of the heteroepitaxial layers, 15 periods of a ZnO/Zn0.6Mg0.4O superlattice structure have been inserted between the conventional double HT-MgO/LT-ZnO buffer and a main HT-ZnO layer. TDHM has revealed a very high mobility close to the values measured in a bulk ZnO for the temperature range of 20 - 300 K. However, TEM investigations of the samples have not indicated any decrease in the dislocation density comparing with the similar samples without a superlattice. Such a high mobility has been attributed to an electron transport in the superlattice structure. Heteroepitaxial growth of high quality ZnO-layers has proven to be challenging leaving the homoepitaxial growth as the only possibility to obtain the epitaxial layers with the best structural and electrical properties. The hydrothermally grown bulk ZnO substrates from two supplying companies, CrysTec and TokyoDenpa, have been employed for homoepitaxy. The substrates from CrysTec have not been epi-ready. Although AFM images reveal very flat surface, this has been damaged by the process of the chemomechanical polishing. This damaged layer must be removed. This has been achieved by the thermal annealing for 3 hours at 1050°C in ambient air. The thermally treated surfaces resulted in atomically flat terraces. XRD measurements have indicated an improvement of the crystal quality after annealing. The resistivity of the bulk substrates decreased after the thermal treatment due to out-diffusion of the compensating Li atoms letting Al, Ga and In atoms to contribute to conduction. After the longer annealing processes the etch-pits have been discovered on O-polar faces. The same features could be achieved by the chemical etching in a nitric acid on Zn-polar faces. The density of the threading dislocations on both polar faces for both types of substrates calculated by the etch-pit density investigation is about 105 1/cm2. Further the thermally treated substrates with atomically flat terraces have been utilized for homoepitaxy. The differences in growth kinetics during the molecular beam epitaxy on such substrates with the improved surface quality depending on their polarity have been investigated by RHEED measurements. The growth on a Zn-polar face has a 3D-character independently on a supplier. Morphologies of the resulting O- and Zn-polar layers have shown to be different. This has been explained by the presence of dangling bonds on Opolar face and thus, shorter diffusion time of the impinging Zn atoms on the surface. XRD and TEM measurements have shown a perfect crystal quality of the overgrown layers. The PL spectra of homoepitaxial layers are governed by the donor impurities diffused from the substrates. Considering the SIMS measurements of homoepitaxial layers found in the literature it has been concluded that the diffusion of donors in the layers grown on Zn-polar faces takes less effect then for the O-polar films. This conclusion has enforced the utilization of Zn-polar substrates supplied by CrysTec for the experiments with nitrogen doping of ZnO because of their affordable price. The electrical properties measured by ECV-profiling in series of homoepitaxial layers with varied growth parameters have shown an increase of the carrier concentration with the nitrogen incorporation. In addition, it has also been shown that the resulting electrical properties near the interface are governed mostly by the initial properties of the substrates. With increasing thickness of the layers carrier concentration saturated to the values of around 1016 1/cm3. The recent successful realization of the p-type MgZnO layers on TokyoDenpa substrates by researchers from Japan suggests switching to the p-type doped alloys because the above discussed results indicate that p-type doping with nitrogen of a pure ZnO is very difficult or even impossible. This is due to a rather fundamental reason: the formation of the compensating donor centers with the incorporation of acceptor atoms. As the first step in the future works, it is obvious to try to reproduce the results of the ZnMgO p-type doping with nitrogen employing growth on ZnO substrates.

Download or read book Morphology and Optical Properties of Zinc Oxide Thin Films Grown on Si 100 by Metal organic Chemical Vapor Deposition written by 籃山明 and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Growth and Characterization of Epitaxial ZnO Thin Films on GaN 0001 Epilayers and ZnO 0001 Substrates Using Metalorganic Chemical Vapor Depositon written by Jonathan Mark Pierce and published by . This book was released on 2004 with total page 60 pages. Available in PDF, EPUB and Kindle. Book excerpt: Keywords: epitaxial, ZnO, doping, thin films.

Download or read book Science Abstracts written by and published by . This book was released on 1992 with total page 1228 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Ceramic Abstracts written by American Ceramic Society and published by . This book was released on 1997 with total page 1058 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1994 with total page 892 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Optical Properties of Zinc Oxide Nanotips and Their Device Applications written by and published by . This book was released on 2007 with total page 135 pages. Available in PDF, EPUB and Kindle. Book excerpt: Zinc oxide (ZnO) nanostructures are emerging as the key building blocks for nanoscale optoelectronic and electronic devices. ZnO has a large exciton binding energy (~ 60 meV), which makes its nanotips ideal for studying excitonic emissions in one-dimensional systems even at room temperature. ZnO nanowires show a strong exciton-polariton interaction, promising for fabricating UV nanolasers. The large and fast photoconductivity in high quality ZnO is suitable for making UV photodetectors. ZnO nanotips can be grown on various substrates, including glass, Si, and GaN, at low growth temperature (~ 400° C) by metal-organic chemical vapor deposition (MOCVD) that provides the potential of the integration of ZnO nanotips with Si based microelectronics and GaN based optoelectronics devices. To date, most of the research has been focused either on ZnO films, or on "pick-and-place" manipulation of randomly dispersed ZnO nanowires to study their physical properties. In this dissertation work in-situ n-type doping of ZnO nanotips during MOCVD is studied, including the doping effects on optical properties and electrical conductivity. Nanoscale tunneling current-voltage characteristics of the ZnO nanotips show the conductivity enhancement due to Ga doping at the proper range of doping concentration. At low or moderate doping levels, the increase in photoluminescence (PL) intensity from Ga doping is attributed to the increase of Ga donor related impurity emission. The excitonic emissions of ZnO nanotips are investigated using temperature-dependent PL spectroscopy. The sharp free exciton and donor-bound exciton peaks are observed at 4.4K, confirming high optical quality of the ZnO nanotips. Free exciton emission dominates at temperatures above 50K. The thermal dissociation of these bound excitons forms free excitons and neutral donors. Temperature-dependent free A exciton peak emission is fitted to the Varshni's equation to study the variation of energy bandgap versus temperature. A prototype of ZnO nanotips/GaN light emitting devices has been demonstrated using an n-ZnO nanotips/p-GaN heterostructure. The electroluminescence with a peak wavelength of 406nm is primarily due to radiative recombination from electron injection from n-type ZnO nanotips into p-type GaN. A novel integrated ZnO nanotips/GaN LED has been fabricated for enhanced light emission efficiency. A Ga-doped ZnO transparent conductive oxide (GZO) film and ZnO nanotips are sequentially grown on top of a GaN LED, serving as the transparent electrode and the light extraction layer, respectively. Compared with the conventional Ni/Au p-metal LED, light output power from the ZnO nanotips/GZO/GaN LED is improved by 1.7 times. The enhanced light extraction is attributed to the increased light scattering and transmission in the ZnO/GaN multilayer.