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Showing 1 to 20 of 36 for “"Epitaxial layers"”.
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Thermal conductivity of UO2 and U3O8 epitaxial layers damaged by ion irradiation
This thesis presents experimental results on thermal conductivity measurements on both irradiated and unirradiated uranium oxides between 90 K and 658 K. The irradiation doses range from 5x10^13 argon ions/cm² to 2x10^16 Ar+/cm² at 2 MeV and room temperature. The main focus lies on 360 – 500 nm …
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Carbon doping of compound semiconductor epitaxial layers grown by metalorganic chemical vapor deposition using carbon tetrachloride
A dilute mixture of CCl$\sb4$ in high purity H$\sb2$ has been used as a carbon dopant source for $\rm Al\sb{x}Ga\sb{1-x}As$ grown by low pressure metalorganic chemical vapor deposition (MOCVD). To understand the mechanism for carbon incorporation from CCl$\sb4$ doping and to provide experimental …
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The Characterization of Liquid Phase Epitaxial Indium-Gallium - Arsenide - Phosphide and Indium-Gallium - Arsenide
… growth parameters to produce high quality epitaxial layers. The lattice mismatch of these layers with respect to the underlying InP substrate was determined by X-ray diffraction, and the energy gap was obtained by optical spectrophotometer transmission measurements. The distribution …
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Optoelektroniniai terahercinio dažnių diapazono komponentai iš puslaidininkių su giliais centrais /
… the optically induced THz absorption of LTG GaAs layers grown on AlAs/GaAs Bragg mirror and annealed at moderate temperature. It was shown that electron lifetime in these layers is less than 1 ps. Induced THz absorption increased linearly with increasing laser pulse intensity. The maximum …
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Terahertz optoelectronics components of semiconductor materials with deep defects /
… the optically induced THz absorption of LTG GaAs layers grown on AlAs/GaAs Bragg mirror and annealed at moderate temperature. It was shown that electron lifetime in these layers is less than 1 ps. Induced THz absorption increased linearly with increasing laser pulse intensity. The maximum …
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Semiconductor Laser Arrays Grown by Metalorganic Chemical Vapor Deposition
… (MOCVD) allows for the growth of ultrathin epitaxial layers of III-V semiconductor compounds. This vapor deposition process is well suited for the growth of high performance semiconductor laser structures. Experimental data have been collected on a variety of MOCVD grown laser structures and …
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Growth, Characterization and Application of Aluminum-Gallium - Arsenide/gallium-Arsenide Modulation Doped Heterostructures
… because of the ease with which high quality epitaxial layers and abrupt compositional and doping profiles may be obtained.
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The growth of aluminum gallium arsenide/gallium arsenide graded barrier quantum well heterostructure lasers on planar and nonplanar substrates by metalorganic chemical vapor deposition
… which has demonstrated the capacity to deposit epitaxial layers possessing the high levels of crystalline quality and material purity required for the fabrication of state of the art devices in a variety of material systems. In this work, the MOCVD process and reactor design and operation are …
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Multi-scale modelling of III-nitrides: from dislocations to the electronic structure
… the lack of suitable lattice-matched substrates, epitaxial layers contain a high density of defects such as dislocations. To reduce their number and to design a device with desired specifications, multilayered systems with varying composition (and thus material properties) are grown. Theoretical …
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Characterization of epitaxial semiconductor films by scanning tunneling microscopy at ambient pressure
Epitaxial layers grown by molecular beam epitaxy on both silicon and gallium arsenide substrates are exposed by cleaving and studied by scanning tunneling microscopy (STM) at ambient pressure. The cleaved surfaces are prepared for imaging by wet chemical treatments. GaAs/AlGaAs and Si/SiGe …
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Investigation on the Properties of Nanowire Structures and Hillocks of Group-III Nitride Materials
… development of 3D bulk nitride substrate; (b) epitaxial layers, for example GaN/InGaN 2D quantum well based light emitting diodes (LEDs); (c) 1D nitride nanowires and (d) 0D quantum dots, for example InGaN quantum dot based single photon sources. This thesis uses a multimicroscopy concept to …
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III-V compound semiconductor integrated charge storage structures for dynamic and non-volatile memory elements.
… sensing, with each having different bipolar or epitaxial layer structure controlling the junction gate. The bottom epitaxial layer in each case served as the JFET channel. Two of the device types have three alternately doped layers, while the remaining two have four alternately doped layers. In …
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p-Channel gallium nitride transistor on Si substrate
… p-channel transistor. A stack of MOCVD grown epitaxial layers, is chosen for this work which has both 2-dimensional electron gas (2-DEG) for n-channel transistor and 2-dimensional hole gas (2-DHG) for p-channel transistor. The epitaxial layers chosen for this work are as follows, p++ - GaN (20 …
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Analysis of laser diode bar degradation
… from the propagation of dislocations in the epitaxial layers used to create the p-n junction to oxidation of the mirror facets. In addition, degradation mechanisms caused by the packaging process are also common. In order to understand and quantify these degradation mechanisms, a spectrometer …
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Neutron irradiation effects in gallium arsenide
… with fast neutrons have been studied, after epitaxial layers doped with Si at concentrations in the range 1.35 $\times$ 10$\sp{15}$ to 1.60 $\times$ 10$\sp{16}$ cm$\sp{-3}$ were irradiated with reactor neutron fluences up to 1.31 $\times$ 10$\sp{15}$ cm$\sp{-2}.$ When the changes in carrier …
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Growth of a silicon-gallium phosphide heterojunction by liquid and vapour phase epitaxial techniques.
… stages of investigation. If gallium phosphide epitaxial layers can he grown on to silicon substrates then, due to the small cost of the silicon substrates and the electroluminescent properties of the gallium phosphide layer, low cost L E D's could be produced. The gallium phosphide display and …
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Process Development and Characterization of AlGaN/GaN Heterostructure Field-Effect Transistors
… be discussed. Devices were then fabricated on epitaxial layers grown on sapphire substrates and on n-type, p-type, and insulating SiC. While sapphire is the substrate of choice for the nitrides, SiC substrates are better suited for high-power devices due to their significantly higher thermal …
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Fabrication and characterization of avalanche photodetectors
… current we need to improve the design of the epitaxial layers. This work also examines the dependence of cross-talk and the array packing density. A trade-off relation- ship is observed between the packing density of the devices and the leakage current.
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High Growth Rate and High Purity Semi-Insulating Epitaxy Using Dichlorosilane For Power Devices
… (C2H4) is the standard technology of growing epitaxial layers for any device applications. For high-voltage (>10 kV) devices made of SiC thick (>100 μm), low doped (~2x1014 cm-3) epilayers are needed. To obtain such thickness with standard silane-based CVD process, which have growth rates of …
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