Growth Kinetics of III-V Semiconductor Thin Films by Molecular Beam Epitaxy with Gas Sources PDF Download
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Author: Bingwen Liang
Publisher:
ISBN:
Category :
Languages : en
Pages : 214
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Author: Bingwen Liang
Publisher:
ISBN:
Category :
Languages : en
Pages : 214
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Author: Li-Kang Li
Publisher:
ISBN:
Category :
Languages : en
Pages : 220
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Author: Marian A. Herman
Publisher: Springer Science & Business Media
ISBN: 3642970982
Category : Technology & Engineering
Languages : en
Pages : 394
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Book Description
This first-ever monograph on molecular beam epitaxy (MBE) gives a comprehensive presentation of recent developments in MBE, as applied to crystallization of thin films and device structures of different semiconductor materials. MBE is a high-vacuum technology characterized by relatively low growth temperature, ability to cease or initiate growth abruptly, smoothing of grown surfaces and interfaces on an atomic scale, and the unique facility for in situ analysis of the structural parameters of the growing film. The excellent exploitation parameters of such MBE-produced devices as quantum-well lasers, high electron mobility transistors, and superlattice avalanche photodiodes have caused this technology to be intensively developed. The main text of the book is divided into three parts. The first presents and discusses the more important problems concerning MBE equipment. The second discusses the physico-chemical aspects of the crystallization processes of different materials (mainly semiconductors) and device structures. The third part describes the characterization methods which link the physical properties of the grown film or structures with the technological parameters of the crystallization procedure. Latest achievements in the field are emphasized, such as solid source MBE, including silicon MBE, gas source MBE, especially metalorganic MBE, phase-locked epitaxy and atomic-layer epitaxy, photoassisted molecular layer epitaxy and migration enhanced epitaxy.
Author: Mohamed Henini
Publisher: Elsevier
ISBN: 0128121378
Category : Science
Languages : en
Pages : 790
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Book Description
Molecular Beam Epitaxy (MBE): From Research to Mass Production, Second Edition, provides a comprehensive overview of the latest MBE research and applications in epitaxial growth, along with a detailed discussion and ‘how to’ on processing molecular or atomic beams that occur on the surface of a heated crystalline substrate in a vacuum. The techniques addressed in the book can be deployed wherever precise thin-film devices with enhanced and unique properties for computing, optics or photonics are required. It includes new semiconductor materials, new device structures that are commercially available, and many that are at the advanced research stage. This second edition covers the advances made by MBE, both in research and in the mass production of electronic and optoelectronic devices. Enhancements include new chapters on MBE growth of 2D materials, Si-Ge materials, AIN and GaN materials, and hybrid ferromagnet and semiconductor structures. Condenses the fundamental science of MBE into a modern reference, speeding up literature review Discusses new materials, novel applications and new device structures, grounding current commercial applications with modern understanding in industry and research Includes coverage of MBE as mass production epitaxial technology and how it enhances processing efficiency and throughput for the semiconductor industry and nanostructured semiconductor materials research community
Author: R.F.C. Farrow
Publisher: Springer Science & Business Media
ISBN: 1468491458
Category : Technology & Engineering
Languages : en
Pages : 548
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Book Description
This work represents the account of a NATO Advanced Research Workshop on "Thin Film Growth Techniques for Low Dimensional Structures", held at the University of Sussex, Brighton, England from 15-19 Sept. 1986. The objective of the workshop was to review the problems of the growth and characterisation of thin semiconductor and metal layers. Recent advances in deposition techniques have made it possible to design new material which is based on ultra-thin layers and this is now posing challenges for scientists, technologists and engineers in the assessment and utilisation of such new material. Molecular beam epitaxy (MBE) has become well established as a method for growing thin single crystal layers of semiconductors. Until recently, MBE was confined to the growth of III-V compounds and alloys, but now it is being used for group IV semiconductors and II-VI compounds. Examples of such work are given in this volume. MBE has one major advantage over other crystal growth techniques in that the structure of the growing layer can be continuously monitored using reflection high energy electron diffraction (RHEED). This technique has offered a rare bonus in that the time dependent intensity variations of RHEED can be used to determine growth rates and alloy composition rather precisely. Indeed, a great deal of new information about the kinetics of crystal growth from the vapour phase is beginning to emerge.
Author: Abdelhamid Abdelrehim Mahmoud Elshaer
Publisher: Cuvillier Verlag
ISBN: 3736927010
Category : Computers
Languages : en
Pages : 144
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Book Description
In semiconductor research a reliable epitaxial growth technique for growing high quality thin films and heterostructures is necessary. In the case of ZnO one of the main difficulties is the absence of suitable substrate material for ZnO epitaxial growth. Although special oxide material (for example ScAlMgO4) and ZnO bulk crystal can serve as lattice matched substrates, the quality of the substrates themselves, the size of the available wafer, and the expense do not encourage to use these lattice matched substrates for ZnO epitaxial growth. In the current research, a widely used low cost commercial substrate sapphire was employed to develop a reliable epitaxial growth technique and growth process for ZnO. The versatile epitaxial growth technique, molecular beam epitaxy (MBE) equipped with a rf-plasma source was developed for growth and various characterizations methods were conducted to obtain a fundamental understanding in both the epitaxial processes and material properties of ZnO thin films and heterostructures. Employing a thin HT MgO buffer layer prior to ZnO growth is the key to overcome the very large mismatches between c-Al2O3 substrate. Wetting the surface of Al2O3 substrate with a few MgO monolayers, lowed the surface energy, so that the lateral growth of ZnO is promoted at the initial growth stage. MgO can be grown in the same chamber as ZnO without any contamination problem. These advantages make the growth procedure of a HT MgO buffer fast and easy. The growth temperature and the growth rate of MgO buffer are found to be important to improve the ZnO heteroepitaxy. An intermediate spinel layer in epitaxial relation with the sapphire substrate as well as with the HT MgO buffer layer is formed in the early stage of growth during the deposition of the MgO at 700°C. It was found that the combination of these two layers is useful for the progressive reduction of the ZnO overgrown with the sapphire substrate.Annealing experiments reveal that as soon as the spinel layer is formed at about 700°C, it remains stable at least up to 1000°C, and even it is extended in thickness. By recording and analyzing RHEED intensity oscillations, the growth kinetics has been investigated. Flat surface morphology and layer-by-layer growth has been achieved. The stoichiometry has been deduced by analyzing the growth rate as a function of Zn and O fluxes for various growth temperatures. It is found that the sticking coefficient of oxygen radicals is less dependent on the substrate temperature than that of Zn. The stoichiometric condition shifts to larger Zn flux at higher growth temperature. The kink rZnO values determine the activated O-flux supplied by the RF plasma source at TS=500°C, 400W and a given O2-flow rate. It equals 0.5±0.05 Ås-1 per sccm. Absolute αZn values versus TS, defined as αZn=rZnO(T)/rZnO(max), where rZnO(max) is recalculated from the Zn flux measured by a quartz monitor, using Zn/ZnO molar mass and density ratios. Ex-situ characterization of the grown ZnO layers indicate that the surface morphology and crystal quality of the ZnO films grown on sapphire by MBE using either oxygen plasma cell or H2O2 as an oxidant can be extensively improved by using an HT MgO buffer. ZnO layers reveal strong variation of surface morphology versus the O/Zn flux ratio. The most flat surface morphology of ZnO is obtained when the ratio is within the 0.7-1 range. The growth under O-rich conditions leads to formation of hexagonal pyramids and at higher O/Zn ratios to a 3D growth with the top layer formed by perfectly c-oriented columnar structures of 50-100 nm in a diameter. It was also possible to recover the initial 3D growth mode to the 2D one by employing the Zn-rich growth conditions at O/Zn=0.4-0.6. Structural characterizations by high resolution X-ray diffraction (HR-XRD) and transmission electron microscopy (TEM) indicate a dramatic reduction in defect density in the ZnO epilayers grown with an HT MgO buffer. By using TEM, it was found that the dominant extending defects are edge, screw and mixed-type dislocations along c-axis. The main defects were threading dislocations. This is resulted from the well controlled layer-by-layer growth, since only the edge-type dislocation is able to accommodate the lattice mismatch, while the screw type dislocation forms much related to the initial nucleation environment.The microstructure of ZnO epilayers has been studied by HR-XRD. The full width at half maximum of the (0002) reflection, 0.007 degree, is much smaller than that of the (10-10) reflection, 0.27 degree revealing the micro-twist dominates the mosaicity, while micro-tilt is much less important.This pronounced difference of the rocking curve widths between the (0002) and (1010) reflections strongly indicates that the density of pure edge threading dislocations is greater than that of pure screw dislocations. Optical characterizations reveal that exciton plays an important role in ZnO. At room temperature free exciton recombinations dominate the photoluminescence. The ZnO epilayers reveal well resolved low temperature PL excitonic spectra with a dominant bound exciton line (3.355 eV) possessing a ~2 meV half-width and a peak of free A exciton at 3.374 eV. The low-energy tail extending from the excitonic emission peaks due to the lattice deformation is significantly reduced, which allows the observation of two electron satellites and LO-phonons replicas of free and bound excitons. Variation of growth stoichiometry from O-rich to Zn-rich results in the pronounced quench of the acceptor-bound part of the excitonic band, as well as the strong intensity redistribution of donor-bound lines which seems to be attributed to a change in the point defect density. Temperature dependence of PL spectra between 6K and room temperature every 30 K under the same excitation conditions was performed. Slowly decreases coming at 300K to about one third of the intensity at 6K. This corresponds to the activation of non-radiative channels in the capturing and recombination processes. This result was confirm by decay time measurements. PL mapping of 2 inch ZnO epilayer shows high lateral homogeneity from PL intensity distribution and PL FWHM distribution. Hall-effect measurements and Electrochemical profiling (ECV) were used to characterize the electrical properties of ZnO samples. Hall-effect measurements indicated n-type behavior with carrier concentration of 2.0x1016 cm-3 and mobility of approximately 96 cm2/Vs. ECV profile versus depth measured for the top 2.5 μm thick sample gives surface carrier concentration is 2.0x1016 cm-3 increasing to a maximum value of 1.0x1018 cm-3 the semiconductor/substrate interface. P-n heterojuntions and mesa structures comprising MBE n-ZnO layers and CVD p-4H-SiC laser were manufactured and investigated. Electrical properties of the mesa diodes have been studied with Hall measurements, and current-voltage measurements (I-V). I-V measurements of the device show good rectifying behavior, from which a turn-on voltage of about 2 V was obtained. With the excitation of O and N gas mixture in a single plasma cell, followed by the sample annealing procedure. P-type ZnO:N layers with a net hole concentration 3x1017 cm-3 using was measured. The combination of low growth temperature, slightly O-rich conditions and post-growth annealing is shown to be effective way to obtain p-doping. Further efforts are necessary to improve structural quality of the low-temperature p-type ZnO:N films. Optical properties of ZnO based II-VI heterostructures and quantum structures have also been studied. The surface roughness of ZnxMg1−xO was as low as 0.7 nm. The optical band gap and photoluminescence peak can be turned to larger energy with the same high crystallinity and without significant change in the lattice constant. The prominent PL peaks related to the SQW show a systematic blueshift with decreasing well width, which is consistent with the quantum size effect. The SQW-related emission peaks exhibit an S-shaped (redshift-blueshiftredshift) behaviour with increasing temperature, which is in contrast with that ascribed to band gap shrinkage (redshift). The observed behavior is discussed in terms of localization at lateral interface potential fluctuations. For T >70 K the integrated PL intensity is thermally activated with activation energies much less than the band offsets. It is argued that the dominant mechanism leading to the quenching of the ZnO SQW-related PL is due to the thermionic emission of excitons out of the lateral potential minima caused by potential fluctuations, such as interface fluctuations by 1 ML. Stimulated emission has been achieved at room temperature in a separate confinement double heterostructure having a 3 nm wide SQW as an active region. It has been found that a critical parameter for the lasing is the inhomogeneous broadening of both QW and barrier emission bands. MBE process for ZnO has been developed where high quality ZnO epilayers and heterostructures can be grown by molecular beam epitaxy on sapphire substrate. For nitrogen doping of ZnO, Oxygen and nitrogen were activated in the single plasma cell. No reproducible and reliable experimental results on the achievement of p-type conductivity achieved. Stimulated emission has been achieved at room temperature.
Author: Gregory Joseph Whaley
Publisher:
ISBN:
Category :
Languages : en
Pages : 266
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Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Author: John E. Ayers
Publisher: CRC Press
ISBN: 1482254360
Category : Technology & Engineering
Languages : en
Pages : 660
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Book Description
In the past ten years, heteroepitaxy has continued to increase in importance with the explosive growth of the electronics industry and the development of a myriad of heteroepitaxial devices for solid state lighting, green energy, displays, communications, and digital computing. Our ever-growing understanding of the basic physics and chemistry underlying heteroepitaxy, especially lattice relaxation and dislocation dynamic, has enabled an ever-increasing emphasis on metamorphic devices. To reflect this focus, two all-new chapters have been included in this new edition. One chapter addresses metamorphic buffer layers, and the other covers metamorphic devices. The remaining seven chapters have been revised extensively with new material on crystal symmetry and relationships, III-nitride materials, lattice relaxation physics and models, in-situ characterization, and reciprocal space maps.
Author: R.F.C. Farrow
Publisher: Springer
ISBN: 9781468491470
Category : Technology & Engineering
Languages : en
Pages : 552
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Book Description
This work represents the account of a NATO Advanced Research Workshop on "Thin Film Growth Techniques for Low Dimensional Structures", held at the University of Sussex, Brighton, England from 15-19 Sept. 1986. The objective of the workshop was to review the problems of the growth and characterisation of thin semiconductor and metal layers. Recent advances in deposition techniques have made it possible to design new material which is based on ultra-thin layers and this is now posing challenges for scientists, technologists and engineers in the assessment and utilisation of such new material. Molecular beam epitaxy (MBE) has become well established as a method for growing thin single crystal layers of semiconductors. Until recently, MBE was confined to the growth of III-V compounds and alloys, but now it is being used for group IV semiconductors and II-VI compounds. Examples of such work are given in this volume. MBE has one major advantage over other crystal growth techniques in that the structure of the growing layer can be continuously monitored using reflection high energy electron diffraction (RHEED). This technique has offered a rare bonus in that the time dependent intensity variations of RHEED can be used to determine growth rates and alloy composition rather precisely. Indeed, a great deal of new information about the kinetics of crystal growth from the vapour phase is beginning to emerge.
