Surface characteristics of etched and non-etched silicon germanium (SiGe)/Si graded structure with varying Ge concentration grown by ultra-high vacuum (UHV)/chemical vapor deposition (CVD) for optoelectronic and power conversion applications PDF Download
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Author: Fred Semendy
Publisher:
ISBN:
Category : Chemical vapor deposition
Languages : en
Pages : 16
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Book Description
Author: Fred Semendy
Publisher:
ISBN:
Category : Chemical vapor deposition
Languages : en
Pages : 16
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Book Description
Author: Gudrun Kissinger
Publisher: CRC Press
ISBN: 1466586656
Category : Science
Languages : en
Pages : 424
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Book Description
Despite the vast knowledge accumulated on silicon, germanium, and their alloys, these materials still demand research, eminently in view of the improvement of knowledge on silicon-germanium alloys and the potentialities of silicon as a substrate for high-efficiency solar cells and for compound semiconductors and the ongoing development of nanodevic
Author: D. Harame
Publisher: The Electrochemical Society
ISBN: 1566778255
Category : Science
Languages : en
Pages : 1066
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Book Description
Advanced semiconductor technology is depending on innovation and less on "classical" scaling. SiGe, Ge, and Related Compounds has become a key component in the arsenal in improving semiconductor performance. This symposium discusses the technology to form these materials, process them, FET devices incorporating them, Surfaces and Interfaces, Optoelectronic devices, and HBT devices.
Author: Erich Kasper
Publisher: Inst of Engineering & Technology
ISBN: 9780852967836
Category : Technology & Engineering
Languages : en
Pages : 358
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Book Description
The industrial relevance of SiGe has increased dramatically in the last few years with the manufacture of heterojunction bipolar circuits for the commercial wireless and datacomms markets by IBM and TEMIC. Major high technology companies see the development and use of SiGe as an important part of their strategy, so that there is a strong impetus to improve its characterization and exploitation. This liberally illustrated and fully indexed volume distills in a homogeneous, structured way the expertise of some 40 invited authors to comprehensively review the whole range of properties as well as SiGe; C, self-assembled nanostructures, quantum effects and device trends.
Author: Yan Cai (Ph. D.)
Publisher:
ISBN:
Category :
Languages : en
Pages : 197
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Book Description
Germanium (Ge) is an optically active material with the advantages of Si-CMOS compatibility and monolithic integration. It has great potential to be used as the light emitter for Si photonics. Tensile strain and n-type doping are two key properties in Ge to achieve optical gain. This thesis mainly focuses on: (1) physical understandings of the threshold behavior of Ge-on-Si bulk laser and the temperature dependent performance; (2) process developments to grow and planarize the epitaxial Ge on Si in oxide trenches and corners; (3) introduction of n-type dopant into Ge-on-Si thin films while studying the threading dislocation behavior in n-Ge during annealing; (4) Design an external cavity Ge laser integrated with Si waveguides for a low threshold current and single mode operation. Heavy n-type doping was observed to change the Ge electronic band structure by band gap narrowing effect. We also found a failure of using a simple Drude model to explain free carrier absorption in n-Ge. We modified the optical gain simulation based on the above two observations in Ge. We found a broad gain bandwidth of ~ 200 nm from 1550 nm to 1750 nm and a higher net materials gain. We predicted a theoretical lasing threshold current density of 5~10 kA/cm2 in the bulk Ge laser device with the n-type doping of mid-1019 cm-3 at room temperature. We also predicted the Ge laser device would have better temperature stability regarding the threshold current compared to the III-V laser. Single crystalline Ge was epitaxial grown on Si in oxide trenches using ultra high vacuum chemical vapor deposition. The selective growth lead to the faceting in Ge because of the different growth rates of crystal orientations. We developed a suitable photolithography and oxide etch process to get the vertical oxide sidewall for Ge trench filling. We also tested the Ge growth in the T-shape corners to improve the reflectivity at the waveguide end. The T-shape structure was also useful for the Ge/Si waveguide coupling in the external cavity laser. Furthermore, we developed a chemical mechanical polishing (CMP) process for the over-grown Ge waveguides. The Ge CMP process was selective to oxide, flexible to change in the CMP rate by DI water dilution and controllable for a minimum dishing of Ge in the oxide trenches. N-type doping helped to increase the direct band transition in Ge for light emission. We developed a delta-doping method to grow a dopant source called "delta doping layer" on the single crystalline Ge layer without introducing extra defects. We then used rapid thermal annealing to drive the dopant into the underlying Ge layer. The dopant enhanced diffusion was discovered to speed up the drive-in process. The active n-type concentration in Ge could reach up to 5×1019 cm-3 using the delta doping source and annealing process. Since the dopant source layer had a disrupted Ge growth, we used the developed CMP process to remove it after the dopant drive-in. A comprehensive dopant diffusion simulation was developed to predict the annealing temperature and time to achieve high n-type doping and uniform distribution. We used plan-view transmission electron microscopy to examine the threading dislocation density (TDD) in n-Ge for both blanket films and trench grown waveguides. We found a high TDD of ~ 1×108cm-2 in 1 [mu]m thick blanket Ge with doping of 3×1018 cm-3 after high temperature annealing at 850 °C for 40 min. The TDD is 1×109 cm-2 in the 300 nm thick and 1 [mu]m wide Ge waveguide. We examined the effects of annealing temperature, Ge thickness, Si/Ge inter-diffusion and trench width on the threading dislocation behavior. However, we have not found the exact reason causing the high TDD and therefore, further study is required on the TDD reduction for the Ge waveguide. Finally, we designed an external cavity Ge laser using distributed Bragg reflector (DBR) gratings on Si waveguides. A detailed discussion on the cross section design was presented to mitigate the internal optical loss from claddings and metal layers and to improve the current injection uniformity across the Ge waveguide. The aim of the DBR grating design was to achieve a single mode operation by controlling the full width half maximum of the grating reflectance spectrum. We also discussed the coupling between Ge and Si waveguides and different designs were presented to increase the coupling efficiency.
Author: Erich Kasper
Publisher: Inst of Engineering & Technology
ISBN: 9780863415579
Category : Technology & Engineering
Languages : en
Pages : 372
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Book Description
The industrial relevance of SiGe has increased dramatically in the last few years with the manufacture of heterojunction bipolar circuits for the commercial wireless and datacomms markets by IBM and TEMIC, with over 20 companies planning manufacture in the near future. Major high technology companies see the development and use of SiGe as an important part of their strategy, so that there is a strong impetus to improve its characterization and exploitation. This liberally illustrated and fully indexed volume distils in a homogeneous, structured way the expertise of some 40 invited authors to comprehensively review the whole range of properties as well as SiGe: C, self-assembled nanostructures, quantum effects and device trends. The book contains 75% more text than Prof. Kasper's earlier book Properties of strained and relaxed SiGe (INSPEC, IEE, 1995), thoroughly updates its content and adds many new topics.
Author: Suresh C. Jain
Publisher:
ISBN:
Category : Science
Languages : en
Pages : 328
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Book Description
Biaxial strain in coherent GeSi layers grown on Si substrates provides a powerful tool for tailoring bandgaps and band offsets. Extremely high electron and hole mobilities have been obtained in modulation-doped GeSi strained layer heterostructures. Ultra-high-speed Heterojunction Bipolar Transistors and MODFETs, and long wavelength (1 to 20 micrometre) IR Detectors have been fabricated using these layers. Quantum wells, ultra-thin period superlattices, and quantum dots can also be fabricated using the strained layers. These devices were previously implemented using III-V semiconductors. Now they can be fabricated using existing Si technology, which is mature and reliable. GeSi strained layer technology has made it possible to manufacture monolithic Si integrated circuits containing heterojunction devices.
Author: Perrin Walker
Publisher: CRC Press
ISBN: 9781439822531
Category : Science
Languages : en
Pages : 1434
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Book Description
This publication presents cleaning and etching solutions, their applications, and results on inorganic materials. It is a comprehensive collection of etching and cleaning solutions in a single source. Chemical formulas are presented in one of three standard formats - general, electrolytic or ionized gas formats - to insure inclusion of all necessary operational data as shown in references that accompany each numbered formula. The book describes other applications of specific solutions, including their use on other metals or metallic compounds. Physical properties, association of natural and man-made minerals, and materials are shown in relationship to crystal structure, special processing techniques and solid state devices and assemblies fabricated. This publication also presents a number of organic materials which are widely used in handling and general processing...waxes, plastics, and lacquers for example. It is useful to individuals involved in study, development, and processing of metals and metallic compounds. It is invaluable for readers from the college level to industrial R & D and full-scale device fabrication, testing and sales. Scientific disciplines, work areas and individuals with great interest include: chemistry, physics, metallurgy, geology, solid state, ceramic and glass, research libraries, individuals dealing with chemical processing of inorganic materials, societies and schools.
Author: Meekyung Kim (Ph. D.)
Publisher:
ISBN:
Category :
Languages : en
Pages : 159
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Book Description
The goal of this thesis is to develop and understand processing conditions that improve the surface morphology and reduce the dislocation density in limited-area heteroepitaxy of Ge and SiGe on Si (100) substrates. Low pressure chemical vapor deposition was investigated for two limiting cases of strain states: thin, strained, high Ge content SiGe films for transistor applications, and thick, relaxed Ge films, for potential optoelectronic applications. Selective epitaxial growth of thin, high Ge-content, strained SiGe on oxide-patterned silicon was studied, specifically the effect of growth area on the critical thickness. The critical thickness of Sio.33Geo.67 formed by selective epitaxial growth in areas of 2.3 x 2.3 [mu]m was found to be 8.5 nm, which is an increase of 2x compared to the critical thickness observed for growth in large areas (i.e. for non-selective epitaxy). The sources of misfit dislocation nucleation in selective growth were analyzed, and misfit generation from the SiGe pattern edges, due to effects such as local strain concentration, Si surface shape near the oxide boundary, and preferential SiGe growth near the pattern edge were investigated. Thin, smooth Ge-on-Si films were developed and the effect of growth conditions on film morphology was examined to find an optimum temperature and pressure for smooth film surface (365 °C and 60 torr). A period of delayed epitaxial growth, or "incubation time" was observed, and a Si surface treatment technique, consisting of a short SiGe pulse, with negligible SiGe thickness, was employed to realize uniform Ge films with low surface roughness (RMS
Author: Kevin A. McComber
Publisher:
ISBN:
Category :
Languages : en
Pages : 136
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Book Description
The integration of photonics with electronics has emerged as a leading platform for microprocessor technology and the continuation of Moore's Law. As electronic device dimensions shrink, electronic signals encounter crippling delays and heating issues such that signal transduction across large on-chip distances becomes increasingly more difficult. However, these issues may be mitigated by the use of photonic interconnects combined with electronic devices in electronic-photonic integrated circuits (EPICs). The electronics in proposed EPIC designs perform the logic operations and short-distance signal transmission, while photonic devices serve to transmit signals over longer lengths. However, the photonic devices are large compared to electronic devices, and thus the two types of devices would ideally exist on separate levels of the microprocessor stack in order to maximize the amount of silicon substrate available for electronic device fabrication. A CMOS-compatible back-end process for the fabrication of photonic devices is necessary to realize such a three-dimensional EPIC. Back-end processing is limited in thermal budget and does not present a single-crystal substrate for epitaxial growth, however, so high-quality crystal fabrication methods currently used for photonic device fabrication are not possible in back-end processing. This thesis presents a method for the fabrication of high-quality germanium single crystals using CMOS-compatible back-end processing. Initial work on the ultra-high vacuum chemical vapor deposition of polycrystalline germanium on amorphous silicon is presented. The deposition can be successfully performed by using a pre-growth hydrofluoric acid dip and by limiting the thickness of the amorphous silicon layer to less than 120 nm. Films deposited at temperatures of 350° C, 450° C, and 550° C show (110) texture, though the texture is most prevalent in growths at 450° C. Poly-Ge grown at 4500 C is successfully doped n-type in situ, and the grain size of as-grown material is enhanced by lateral growth over a barrier. Structures are fabricated for the growth of Ge confined in one dimension. The growths show faceting across large areas, in contrast to as-deposited poly-Ge, corresponding to enhanced grain sizes. Growth confinement is shown to reduce the defect density as the poly-Ge grows. When coalesced into a continuous film, the material grown from 1 D confinement exhibits a lower carrier density and lower trap density than as-deposited poly-Ge, indicating improved material quality. We measure an increased grain size from as-deposited poly-Ge to Ge grown from ID confinement. Single-crystal germanium is grown at 450° C from confinement in two dimensions. Such growths exhibit faceting across the entire crystal as well as the presence of E3 boundaries ({111} twins), with many growths showing no other boundaries. These twins mediate the growth of the crystal, as they serve as the points for heterogeneous surface nucleation of adatom clusters. The twins can form after the crystal nucleates and are strongly preferred in order to obtain appreciable crystal growth rates. We model the growths from the confining channels in order to find the optimum channel geometry for large, uniform, single-crystal growths that consistently emerge from the channel. The growths from 2D confinement show lower trap density than those from 1 D confinement, indicating a further enhancement of the crystal quality due to the increased confinement. This method of single-crystal growth from an amorphous substrate is extensible to any materials system in which selective non-epitaxial deposition is possible.
