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

View

Book Description

Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 9

View

Book Description
Structural perfection of silicon carbide (SiC) single crystals is essential to achieve high-performance power devices. A new bulk growth process for SiC proposed by researchers at NASA Glenn Research Center, called large tapered crystal (LTC) growth, based on axial fiber growth followed by lateral expansion, could produce SiC boules with potentially as few as one threading screw dislocation per wafer. In this study, the lateral expansion aspect of LTC growth is addressed through analysis of lateral growth of 6H-SiC a/m-plane seed crystals by hot-wall chemical vapor deposition. Preliminary synchrotron white-beam x-ray topography (SWBXT) indicates that the as-grown boules match the polytype structure of the underlying seed and have a faceted hexagonal morphology with a strain-free surface marked by steps. SWBXT Laue diffraction patterns of transverse and axial slices of the boules reveal streaks suggesting the existence of stacking faults/polytypes, and this is confirmed by micro-Raman spectroscopy. Transmission x-ray topography of both transverse and axial slices reveals inhomogeneous strains at the seed-epilayer interface and linear features propagating from the seed along the growth direction. Micro-Raman mapping of an axial slice reveals that the seed contains high stacking disorder, while contrast extinction analysis (g·b and g·b×l) of the linear features reveals that these are mostly edge-type basal plane dislocations. Further high-resolution transmission electron microscopy investigation of the seed-homoepilayer interface also reveals nanobands of different SiC polytypes. A model for their formation mechanism is proposed. Lastly, the implication of these results for improving the LTC growth process is addressed.

Author: Robin Karhu
Publisher: Linköping University Electronic Press
ISBN: 9176851494
Category :
Languages : en
Pages : 40

View

Book Description
Silicon Carbide (SiC) is a wide bandgap semiconductor that has attracted a lot of interest for electronic applications due to its high thermal conductivity, high saturation electron drift velocity and high critical electric field strength. In recent years commercial SiC devices have started to make their way into high and medium voltage applications. Despite the advancements in SiC growth over the years, several issues remain. One of these issues is that the bulk grown SiC wafers are not suitable for electronic applications due to the high background doping and high density of basal plane dislocations (BPD). Due to these problems SiC for electronic devices must be grown by homoepitaxy. The epitaxial growth is performed in chemical vapor deposition (CVD) reactors. In this work, growth has been performed in a horizontal hot-wall CVD (HWCVD) reactor. In these reactors it is possible to produce high-quality SiC epitaxial layers within a wide range of doping, both n- and p-type. SiC is a well-known example of polytypism, where the different polytypes exist as different stacking sequences of the Si-C bilayers. Polytypism makes polytype stability a problem during growth of SiC. To maintain polytype stability during homoepitaxy of the hexagonal polytypes the substrates are usually cut so that the angle between the surface normal and the c-axis is a few degrees, typically 4 or 8°. The off-cut creates a high density of micro-steps at the surface. These steps allow for the replication of the substrates polytype into the growing epitaxial layer, the growth will take place in a step-flow manner. However, there are some drawbacks with step-flow growth. One is that BPDs can replicate from the substrate into the epitaxial layer. Another problem is that 4H-SiC is often used as a substrate for growth of GaN epitaxial layers. The epitaxial growth of GaN has been developed on on-axis substrates (surface normal coincides with c-axis), so epitaxial 4H-SiC layers grown on off-axis substrates cannot be used as substrates for GaN epitaxial growth. In efforts to solve the problems with off-axis homoepitaxy of 4H-SiC, on-axis homoepitaxy has been developed. In this work, further development of wafer-scale on-axis homoepitaxy has been made. This development has been made on a Si-face of 4H-SiC substrates. The advances include highly resistive epilayers grown on on-axis substrates. In this thesis the ability to control the surface morphology of epitaxial layers grown on on-axis homoepitaxy is demonstrated. This work also includes growth of isotopically enriched 4H-SiC on on-axis substrates, this has been done to increase the thermal conductivity of the grown epitaxial layers. In (paper 1) on-axis homoepitaxy of 4H-SiC has been developed on 100 mm diameter substrates. This paper also contains comparisons between different precursors. In (paper 2) we have further developed on-axis homoepitaxy on 100 mm diameter wafers, by doping the epitaxial layers with vanadium. The vanadium doping of the epitaxial layers makes the layers highly resistive and thus suitable to use as a substrate for III-nitride growth. In (paper 3) we developed a method to control the surface morphology and reduce the as-grown surface roughness in samples grown on on-axis substrates. In (paper 4) we have increased the thermal conductivity of 4H-SiC epitaxial layers by growing the layers using isotopically enriched precursors. In (paper 5) we have investigated the role chlorine have in homoepitaxial growth of 4H-SiC. In (paper 6) we have investigated the charge carrier lifetime in as-grown samples and traced variations in lifetime to structural defects in the substrate. In (paper 7) we have investigated the formation mechanism of a morphological defect in homoepitaxial grown 4H-SiC.

Author: V. Alexander Stefan, Editor
Publisher: Stefan University Press
ISBN: 9781889545394
Category : Science
Languages : en
Pages : 282

View

Book Description

Author: Herbert A. Will
Publisher:
ISBN:
Category : Crystal growth
Languages : en
Pages : 20

View

Book Description

Author: J Matthews
Publisher: Elsevier
ISBN: 0323152120
Category : Science
Languages : en
Pages : 401

View

Book Description
Epitaxial Growth, Part A is a compilation of review articles that describe various aspects of the growth of single-crystal films on single-crystal substrates. The collection contains topics on the historical development of epitaxy, the nucleation of thin films, the structure of the interface between film and substrate, and the generation of defects during film growth. The text also provides descriptions of the methods used to prepare and examine thin films and a list of the overgrowth-substrate combinations studied. Mineralogists, materials engineers and scientists, and physicists will find this book a great source of insight.

Author: B Baliga
Publisher: Elsevier
ISBN: 0323155456
Category : Technology & Engineering
Languages : en
Pages : 337

View

Book Description
Epitaxial Silicon Technology is a single-volume, in-depth review of all the silicon epitaxial growth techniques. This technology is being extended to the growth of epitaxial layers on insulating substrates by means of a variety of lateral seeding approaches. This book is divided into five chapters, and the opening chapter describes the growth of silicon layers by vapor-phase epitaxy, considering both atmospheric and low-pressure growth. The second chapter discusses molecular-beam epitaxial growth of silicon, providing a unique ability to grow very thin layers with precisely controlled doping characteristics. The third chapter introduces the silicon liquid-phase epitaxy, in which the growth of silicon layers arose from a need to decrease the growth temperature and to suppress autodoping. The fourth chapter addresses the growth of silicon on sapphire for improving the radiation hardness of CMOS integrated circuits. The fifth chapter deals with the advances in the application of silicon epitaxial growth. This chapter also discusses the formation of epitaxial layers of silicon on insulators, such as silicon dioxide, which do not provide a natural single crystal surface for growth. Each chapter begins with a discussion on the fundamental transport mechanisms and the kinetics governing the growth rate, followed by a description of the electrical properties that can be achieved in the layers and the restrictions imposed by the growth technique upon the control over its electrical characteristics. Each chapter concludes with a discussion on the applications of the particular growth technique. This reference material will be useful for process technologists and engineers who may need to apply epitaxial growth for device fabrication.

Author: Rachael L. Myers-Ward
Publisher:
ISBN:
Category :
Languages : en
Pages :

View

Book Description
ABSTRACT: This dissertation research focused on the growth of 4H-SiC epitaxial layers in low-pressure horizontal hot-wall chemical vapor deposition (CVD) reactors. The goal of the research was to develop a growth process that maximized the growth rate and produced films of smooth morphology. The epitaxial growth of SiC was carried out in two different reactor sizes, a 75 mm reactor and a 200 mm reactor. The maximum repeatable growth rate achieved was 30-32 um/h in the 200 mm reactor using the standard chemistry of hydrogen-propane-silane (H2-C3H8-SiH4) at growth temperatures

Author: J. W. Matthews
Publisher: Elsevier
ISBN: 1483271811
Category : Science
Languages : en
Pages : 315

View

Book Description
Epitaxial Growth Part B is the second part of a collection of review articles that describe various aspects of the growth of single-crystal films on single-crystal substrates. The topics discussed are the nucleation of thin films, the structure of the interface between film and substrate, and the generation of defects during film growth. The methods used to prepare and examine thin films are described and a list of the overgrowth-substrate combinations studied so far is given.

Author: A N Christensen
Publisher: World Scientific
ISBN: 9814611123
Category : Technology & Engineering
Languages : en
Pages : 556

View

Book Description
Contents:Fundamental Aspects of Crystal Growth from the Melt (C Paorici & L Zanotti)Phase Diagrams in Crystal Growth (A N Christensen)Growth Procedures and Perfection of Semiconductor Materials (A Lindegaard-Andersen)Atomistic Aspects of Crystal Growth and Epitaxy (I Markov)Fundamentals of Liquid Phase Epitaxial Growth (P Kordos)Determination of Few Selected Basic Parameters of the Investigation of AIII-BV Semiconductors Using X-Ray Methods (H Bruhl)Multijunction Solar Cells (I Chambouleyron)Application of the Mossbauer Spectroscopy to the Study of Magnetic Materials (G Albanese)Metallic Magnetism in Modern Materials (D Givord)and others Readership: Materials scientists.