Author: Zhuo (Carol). Chen
Publisher:
ISBN:
Category : Chemical engineering
Languages : en
Pages :
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Book Description
Nano-crystalline Si (nc-Si) is a promising candidate for photovoltaic applications due to its better stability compared to amorphous Si, and relatively easy to manufacture at low cost, by plasma enhanced chemical vapor deposition (PECVD), compared to single crystal Si. The crystalline volume fraction of nc-Si films needs to be well controlled to prevent light-induced degradation of the otherwise amorphous hydrogenated Si (a-Si:H). A layer-by-layer technique using two separate plasma sources for a-Si:H deposition and nano-crystallization was developed. A capacitively-coupled plasma (CCP) with SiH4/He feed gas was used to deposit thin a-Si:H layers that were subsequently exposed to a H2 or D2 inductively-coupled plasma (ICP) to induce crystallization in the films. Deposition and nano-crystallization were performed sequentially and periodically to grow thin films. Raman spectroscopy was used to characterize the films and determine the fraction of crystalline. The crystalline volume fraction obtained in this work ranged from 0% to 72%. Many short exposures (20 s or 5 s) to the plasmas were more effective in producing nano-crystalline Si compared to one long exposure (40 min. or 4 min.). In addition, the fraction of nano-crystalline Si increased with increasing H2 ICP-to-SiH4/He CCP exposure time ratio (from 1/4 to 3/2). The crystallites had columnar structure along the film growth direction based on transmission electron microscopy (TEM). Etching of films by the D2 plasma was monitored by mass spectrometry. At 250 oC, the amorphous Si etching rate (0.25 nm/min) was much lower than the deposition rate (1.4 nm/min), and that etching did not occur exclusively on the surface or the near surface region. The blueshift (by about 1 eV) of the dielectric constants peak, found by spectroscopic ellipsometry (SE), suggested the formation of nano-crystallites in the bulk of the films. It is proposed that by tailoring the CCP deposition time as well as the H2 ICP exposure time per cycle, the crystalline fraction and crystallite size of the resulting films can be controlled for more stable solar cell materials. Further, by spatially separating film deposition and nano-crystallization, each of these processes can be individually optimized, providing flexibility in controlling film nanostructure and properties
Author: Nong Moon Hwang
Publisher: Springer
ISBN: 9401776164
Category : Science
Languages : en
Pages : 338
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Book Description
This book provides a comprehensive introduction to a recently-developed approach to the growth mechanism of thin films and nanostructures via chemical vapour deposition (CVD). Starting from the underlying principles of the low pressure synthesis of diamond films, it is shown that diamond growth occurs not by individual atoms but by charged nanoparticles. This newly-discovered growth mechanism turns out to be general to many CVD and some physical vapor deposition (PVD) processes. This non-classical crystallization is a new paradigm of crystal growth, with active research taking place on growth in solution, especially in biomineralization processes. Established understanding of the growth of thin films and nanostructures is based around processes involving individual atoms or molecules. According to the author’s research over the last two decades, however, the generation of charged gas phase nuclei is shown to be the rule rather than the exception in the CVD process, and charged gas phase nuclei are actively involved in the growth of films or nanostructures. This new understanding is called the theory of charged nanoparticles (TCN). This book describes how the non-classical crystallization mechanism can be applied to the growth of thin films and nanostructures in gas phase synthesis. Based on the author’s graduate lecture course, the book is aimed at senior undergraduate and graduate students and researchers in the field of thin film and nanostructure growth or crystal growth. It is hoped that a new understanding of the growth processes of thin films and nanostructures will reduce trial-and-error in research and in industrial fabrication processes.
Author: Ross Birney
Publisher: MDPI
ISBN: 3036505121
Category : Science
Languages : en
Pages : 154
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Book Description
Today, thin films are near-ubiquitous and are utilised in a very wide range of industrially and scientifically important areas. These include familiar everyday instances such as anti-reflective coatings on ophthalmic lenses, smartphone optics, photovoltaics, decorative, and tool coatings. A range of somewhat more exotic applications also exists, such as astronomical instrumentation (e.g., ultra-low loss dielectric mirrors and beam splitters in gravitational wave detectors, such as laser interferometer gravitational-wave observatory (LIGO)), gas sensing, medical devices and implants, and accelerator coatings (e.g., coatings for the large hadron collider (LHC), and compact linear collider (CLIC) experiments at European organization for nuclear research (CERN)). This Special Issue will provide a platform for researchers working in any area within this highly diverse field to share and exchange their latest research findings. The Special Issue contains novel studies encompassing material characterisation techniques, a range of thin-film coating deposition processes and applications of such technology.
Author: Boon Tong Goh
Publisher:
ISBN:
Category : Plasma-enhanced chemical vapor deposition
Languages : en
Pages : 402
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Book Description
Author: Arvind Victor Shah
Publisher: CRC Press
ISBN: 1439808104
Category : Science
Languages : en
Pages : 438
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Book Description
Photovoltaic technology has now developed to the extent that it is close to fulfilling the vision of a "solar-energy world," as devices based on this technology are becoming efficient, low-cost and durable. This book provides a comprehensive treatment of thin-film silicon, a prevalent PV material, in terms of its semiconductor nature, startin
Author: Pio Capezzuto
Publisher: Elsevier
ISBN: 0080539106
Category : Science
Languages : en
Pages : 339
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Book Description
Semiconductors made from amorphous silicon have recently become important for their commercial applications in optical and electronic devices including FAX machines, solar cells, and liquid crystal displays. Plasma Deposition of Amorphous Silicon-Based Materials is a timely, comprehensive reference book written by leading authorities in the field. This volume links the fundamental growth kinetics involving complex plasma chemistry with the resulting semiconductor film properties and the subsequent effect on the performance of the electronic devices produced. Focuses on the plasma chemistry of amorphous silicon-based materials Links fundamental growth kinetics with the resulting semiconductor film properties and performance of electronic devices produced Features an international group of contributors Provides the first comprehensive coverage of the subject, from deposition technology to materials characterization to applications and implementation in state-of-the-art devices
Author: Mort
Publisher: CRC Press
ISBN: 1351084267
Category : Technology & Engineering
Languages : en
Pages : 253
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Book Description
In Summary, the objective of this book is to present in one volume a review of the plasma deposition process and the present understanding of the most important and widely used plasma deposited thin film materials, devices and their applications.
Author: Alexander D. Pogrebnjak
Publisher: Springer
ISBN: 9811361339
Category : Technology & Engineering
Languages : en
Pages : 380
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Book Description
This book highlights the latest advances in chemical and physical methods for thin-film deposition and surface engineering, including ion- and plasma-assisted processes, focusing on explaining the synthesis/processing–structure–properties relationship for a variety of thin-film systems. It covers topics such as advances in thin-film synthesis; new thin-film materials: diamond-like films, granular alloys, high-entropy alloys, oxynitrides, and intermetallic compounds; ultra-hard, wear- and oxidation-resistant and multifunctional coatings; superconducting, magnetic, semiconducting, and dielectric films; electrochemical and electroless depositions; thin-film characterization and instrumentation; and industrial applications.
Author: Tuo Wang
Publisher:
ISBN:
Category :
Languages : en
Pages : 280
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Book Description
The continuous scaling of microelectronic devices requires high permittivity (high-k) dielectrics to replace SiO2 as the gate material. HfO2 is one of the most promising candidates but the crystallization temperature of amorphous HfO2 is too low to withstand the fabrication process. To enhance the film thermal stability, HfO2 is deposited using atomic layer deposition (ALD), and incorporated with various amorphizers, such as La2O3, Al2O3, and Ta2O5. The incorporation is achieved by growing multiple ALD layers of HfO2 and one ALD layer of MO[subscript x] (M = La, Al, and Ta) alternately (denoted as [xHf + 1M]), and the incorporation concentration can be effectively controlled by the HfO2-to-MO[subscript x] ALD cycle ratio (the x value). The crystallization temperature of 10 nm HfO2 increases from 500 °C to 900 °C for 10 nm [xHf + 1M] film, where x = 3, 3, and 1 for M = La, Al, and Ta, respectively. The incorporation of La2O3, and Ta2O5 will not compromise the dielectric constant of the film because of the high-k nature of La2O3, and Ta2O5. Angle resolved X-ray photoelectron spectroscopy (AR-XPS) reveals that when the HfO2-to-MO[scubscript x] ALD cycle ratio is large enough (x> 3 and 4 for La and Al, respectively), periodic structures exist in films grown by this method, which are comprised of repeated M-free HfO2 ultrathin layers sandwiched between HfM[subscript x]O[scubscript y] layers. Generally, the film thermal stability increases with thinner overall thickness, higher incorporation concentration, and stronger amorphizing capability of the incorporated elements. When the x value is low, the films are more like homogeneous films, with thermal stabilities determined by the film thickness and the amorphizer. When the x value is large enough, the periodically-repeated structure may add an extra factor to stabilize the amorphous phase. For the same incorporation concentration, films with an appropriately high periodicity may have an increased thermal stability. The manner by which the periodic structure and incorporated element affect thermal stability is explored and resolved using nanolaminates comprised of alternating layers of [scubscript y]HfO2 and [xHf + 1M] x n, where y varied from 2 to 20, x varied from 1 to 2, and n varied from 4 to 22.
Author: Çağla Özgit-Akgün
Publisher: LAP Lambert Academic Publishing
ISBN: 9783659208232
Category :
Languages : en
Pages : 180
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Book Description
III-nitride compound semiconductors (AlN, GaN, InN) and their alloys have emerged as versatile and high-performance materials for a wide range of electronic and optoelectronic device applications. Although high quality III-nitride thin films can be grown at high temperatures (>1000 C) with significant rates, deposition of these films on temperature-sensitive device layers and substrates necessitates the adaptation of low-temperature methods such as atomic layer deposition (ALD). When compared to other low-temperature thin film deposition techniques, ALD stands out with its self-limiting growth mechanism, which enables the deposition of highly uniform and conformal thin films with sub-angstrom thickness control. These unique characteristics make ALD a powerful method especially for depositing films on nanostructured templates, as well as preparing alloy thin films with well-defined compositions. This monograph reports on the development of low-temperature ( 200 C) plasma-assisted ALD processes for III-nitrides, and presents detailed characterization results for the deposited thin films and fabricated nanostructures."
