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Author: Hugues Marchand
Publisher: Ann Arbor, Mich. : University Microfilms International
ISBN:
Category :
Languages : en
Pages : 376
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Author: Hugues Marchand
Publisher: Ann Arbor, Mich. : University Microfilms International
ISBN:
Category :
Languages : en
Pages : 376
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Author: L. Liu
Publisher:
ISBN:
Category :
Languages : en
Pages : 4
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Author: L. Liu
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Author: David J. Miller
Publisher: Stanford University
ISBN:
Category :
Languages : en
Pages : 131
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Book Description
Gallium nitride is an important material for the production of next-generation visible and near-UV optical devices, as well as for high temperature electronic amplifiers and circuits; however there has been no bulk method for the production of GaN substrates for device layer growth. Instead, thick GaN layers are heteroepitaxially deposited onto non-native substrates (usually sapphire) by one of two vapor phase epitaxy (VPE) techniques: MOVPE (metalorganic VPE) or HVPE (hydride VPE). Each method has its strengths and weaknesses: MOVPE has precise growth rate and layer thickness control but it is slow and expensive; HVPE is a low-cost method for high rate deposition of thick GaN, but it lacks the precise control and heterojunction layer growth required for device structures. Because of the large (14%) lattice mismatch, GaN grown on sapphire requires the prior deposition of a low temperature MOVPE nucleation layer using a second growth process in a separate deposition system. Here we present a novel hybrid VPE system incorporating elements of both techniques, allowing MOVPE and HVPE in a single growth run. In this way, a thick GaN layer can be produced directly on sapphire. GaN growth commences as small (50-100 nm diameter) coherent strained 3-dimensional islands which coalesce into a continuous film, after which 2-dimensional layer growth commences. The coalescence of islands imparts significant stress into the growing film, which increases with the film thickness until catastrophic breakage occurs, in-situ. Additionally, the mismatch in thermal expansion rates induces compressive stress upon cooling from the growth temperature of 1025°C. We demonstrate a growth technique that mitigates these stresses, by using a 2-step growth sequence: an initial high growth rate step resulting in a pitted but relaxed film, followed by a low growth rate smoothing layer. As a result, thick (> 50 [Mu]m) and freestanding films have been grown successfully. X-ray rocking curve linewidth of 105 arcseconds and 10K PL indicating no "yellow" emission indicate that the material quality is higher than that produced by conventional MOVPE. By further modifying the hybrid system to include a metallic Mn source, it is possible to grow a doped semi-insulating GaN template for use in high frequency electronics devices.
Author: Dirk Ehrentraut
Publisher: Springer Science & Business Media
ISBN: 3642048307
Category : Science
Languages : en
Pages : 337
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This book discusses the important technological aspects of the growth of GaN single crystals by HVPE, MOCVD, ammonothermal and flux methods for the purpose of free-standing GaN wafer production.
Author: Xun Li
Publisher: Linköping University Electronic Press
ISBN: 9175190842
Category : Gallium nitride
Languages : en
Pages : 57
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This thesis aims to develop a chemical vapor deposition (CVD) process for the new directions in both silicon carbon (SiC) and gallium nitride (GaN) epitaxial growth. The properties of the grown epitaxial layers are investigated in detail in order to have a deep understanding. SiC is a promising wide band gap semiconductor material which could be utilized for fabricating high-power and high-frequency devices. 3C-SiC is the only polytype with a cubic structure and has superior physical properties over other common SiC polytypes, such as high hole/electron mobility and low interface trap density with oxide. Due to lack of commercial native substrates, 3C-SiC is mainly grown on the cheap silicon (Si) substrates. However, there’s a large mismatch in both lattice constants and thermal expansion coefficients leading to a high density of defects in the epitaxial layers. In paper 1, the new CVD solution for growing high quality double-position-boundaries free 3C-SiC using on-axis 4H-SiC substrates is presented. Reproducible growth parameters, including temperature, C/Si ratio, ramp-up condition, Si/H2 ratio, N2 addition and pressure, are covered in this study. GaN is another attractive wide band gap semiconductor for power devices and optoelectronic applications. In the GaN-based transistors, carbon is often exploited to dope the buffer layer to be semi-insulating in order to isolate the device active region from the substrate. The conventional way is to use the carbon atoms on the gallium precursor and control the incorporation by tuning the process parameters, e.g. temperature, pressure. However, there’s a risk of obtaining bad morphology and thickness uniformity if the CVD process is not operated in an optimal condition. In addition, carbon source from the graphite insulation and improper coated graphite susceptor may also contribute to the doping in a CVD reactor, which is very difficult to be controlled in a reproducible way. Therefore, in paper 2, intentional carbon doping of (0001) GaN using six hydrocarbon precursors, i.e. methane (CH4), ethylene (C2H4), acetylene (C2H2), propane (C3H8), iso-butane (i-C4H10) and trimethylamine (N(CH3)3), have been explored. In paper 3, propane is chosen for carbon doping when growing the high electron mobility transistor (HEMT) structure on a quarter of 3-inch 4H-SiC wafer. The quality of epitaxial layer and fabricated devices is evaluated. In paper 4, the behaviour of carbon doping using carbon atoms from the gallium precursor, trimethylgallium (Ga(CH3)3), is explained by thermochemical and quantum chemical modelling and compared with the experimental results. GaN is commonly grown on foreign substrates, such as sapphire (Al2O3), Si and SiC, resulting in high stress and high threading dislocation densities. Hence, bulk GaN substrates are preferred for epitaxy. In paper 5, the morphological, structural and luminescence properties of GaN epitaxial layers grown on N-face free-standing GaN substrates are studied since the N-face GaN has advantageous characteristics compared to the Ga-face GaN. In paper 6, time-resolved photoluminescence (TRPL) technique is used to study the properties of AlGaN/GaN epitaxial layers grown on both Ga-face and N-face free-standing GaN substrates. A PL line located at ~3.41 eV is only emerged on the sample grown on the Ga-face substrate, which is suggested to associate with two-dimensional electron gas (2DEG) emission.
Author: Randall M. Feenstra
Publisher: John Wiley & Sons
ISBN: 9780470751824
Category : Technology & Engineering
Languages : en
Pages : 332
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Book Description
Porous Silicon Carbide and Gallium Nitride: Epitaxy, Catalysis, and Biotechnology Applications presents the state-of-the-art in knowledge and applications of porous semiconductor materials having a wide band gap. This comprehensive reference begins with an overview of porous wide-band-gap technology, and describes the underlying scientific basis for each application area. Additional chapters cover preparation, characterization, and topography; processing porous SiC; medical applications; magnetic ion behavior, and many more
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 80
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Author: Rongming Chu
Publisher: Academic Press
ISBN: 0128175443
Category : Electronic apparatus and appliances
Languages : en
Pages : 540
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Book Description
III-Nitride Electronic Devices, Volume 102, emphasizes two major technical areas advanced by this technology: radio frequency (RF) and power electronics applications. The range of topics covered by this book provides a basic understanding of materials, devices, circuits and applications while showing the future directions of this technology. Specific chapters cover Electronic properties of III-nitride materials and basics of III-nitride HEMT, Epitaxial growth of III-nitride electronic devices, III-nitride microwave power transistors, III-nitride millimeter wave transistors, III-nitride lateral transistor power switch, III-nitride vertical devices, Physics-Based Modeling, Thermal management in III-nitride HEMT, RF/Microwave applications of III-nitride transistor/wireless power transfer, and more. Presents a complete review of III-Nitride electronic devices, from fundamental physics, to applications in two key technical areas - RF and power electronics Outlines fundamentals, reviews state-of-the-art circuits and applications, and introduces current and emerging technologies Written by a panel of academic and industry experts in each field
Author:
Publisher:
ISBN:
Category : Electroluminescent devices
Languages : en
Pages : 538
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