Top PDF Development of Zn-IV-Nitride Semiconductor Materials and Devices

Development of Zn-IV-Nitride Semiconductor Materials and Devices

Development of Zn-IV-Nitride Semiconductor Materials and Devices

Grain boundaries in semiconducting materials often result in low electron and hole mobilities and high recombination rates, as carriers do not have ordered lattices to travel through. Efforts to improve crystallinity and achieve larger grain sizes, and thus higher mobilities and longer minority carrier lifetimes, were attempted by grow- ing with higher substrate temperatures. Substrate temperature affects the ad-atom residence time and mobility. Increased ad-atom mobility allows atoms to travel across the substrate and find their energetic minima, potentially producing larger grain sizes as nucleation sites will have formed more thermodynamically favored clusters. Table 2.1 shows deposition parameters for higher temperatures and compared to those for 175C. Figure 2.1 shows that the high temperature growth increased the surface grain morphology compared to ZnSnN 2 deposited at 175C. Surface features increased by 3-4 times size for 375C samples. Although improvements in surface morphology were noted with a higher temperature, FWHM of the (002) peak did not reduce noticibly, inferring the persistence of nanocrystalline grain sizes. Mobilities did not increase noticibly either. GaN thin-films grown by MOCVD can achieve FWHM value lower than 200 arcsec, and ZnSnN 2 peaks only attained FWHM of ~0.3 deg (180 arcmin or 1080 arcsec), leaving much room for improvement. Studies in high temperature growth were limited. Challenges in higher temperature growth lie in thermal expan- sion mismatch of the film and substrate and stability of film during wide temperature variations. ZnSnN 2 was observed to delaminate from sapphire and GaN substrates for deposition and annealing temperatures above 400C.
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Materials Development for Gallium Nitride Power Devices

Materials Development for Gallium Nitride Power Devices

Figure 1.4: Schematic and band diagram of a Ga-polar AlGaN/GaN junction and the formation of 2- dimensional electron gas at its interface. While most research in III-nitride optoelectronic and electronic devices had focused on materials and heterostructures grown in the Ga-polar direction 6 , N-polar HEMTs, first demonstrated only a decade ago 7 , offer several key advantages, especially for high power applications. In N-polar GaN HEMTs, the 2DEG is induced by a back barrier, rather than the top AlGaN layer. This natural back barrier enhances carrier confinement, and presents a barrier to electron injection into the buffer layer. The reduction in carriers injected into the buffer region improves the dynamic performance of the device, making the switching process more efficient. In addition to this, a well-insulated buffer layer from the channel increases the reliability of the transistor. Another advantage of the N-polar orientation for high voltage devices is the AlGaN cap, which maintains a high barrier to vertical electron transport. This, enhanced by the reverse polarity of N-Polar orientation, reduces the gate leakage, and thereby increases the breakdown voltage of the device.
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DEVELOPMENT OF ANTI-FOULING MATERIALS FOR BLOOD- CONTACTING DEVICES

DEVELOPMENT OF ANTI-FOULING MATERIALS FOR BLOOD- CONTACTING DEVICES

CHAPTER IV CONCLUSION The hydrophobicity of silicones and PUs results in poor resistance to protein adsorption, resulting in platelet adhesion and thrombus formation. Bulk-modification of silicones and PUs with hydrophilic, protein resistant PEO can be employed to circumvent the inherent, hydrophobic challenges of these materials. The efficacy of PEO to resist protein adsorptions depends on its ability to restructure when exposed to an aqueous environment to form a PEO-rich layer at the surface.

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Scandium Nitride as a Gateway III-Nitride Semiconductor for Optoelectronic Artificial Synaptic Devices

Scandium Nitride as a Gateway III-Nitride Semiconductor for Optoelectronic Artificial Synaptic Devices

Synapses are responsible for all the computation and memory in the brain. Therefore, mimicking the functionalities of the biological synaptic connection lies at the heart of the development of brain-inspired computational hardware. Though von Neumann identified the similarities between the conventional computer architecture and the human central nervous system and tried to bring out a mathematical underpinning between the two, his untimely death in 1967 halted the substantial progress in the field for some time 5 . However, since the theoretical proposal by Carver Mead in the 1980s 6 , brain-inspired neuromorphic circuits have been developed on conventional CMOS chips to emulate the synaptic functions, for example, TrueNorth chip from IBM 7 , Loihi chip from Intel 8 . However, such neuromorphic integrated circuits are incredibly power-hungry, limiting their utility in cloud-based computing operations and requiring a huge number of feedback loop operations to perform simple functions such as image and voice recognition. Such large room-sized computers are also not a viable alternative to the human brain, and in recent reports, these neuromorphic circuits are also demonstrated to be prone to be biased to their training data and are found to discriminate between races and genders 9 . Therefore, though the CMOS-based neuromorphic computing technology has made great progress over the last 10-15 years, brain-inspired neuromorphic hardware technologies needs to be developed that emulates the synaptic connections in brain with significantly reduced computational power and size 10 .
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Nitride Semiconductor Technology

Nitride Semiconductor Technology

The development of GaN-based power amplifiers for RF, microwave, and mm-wave applications would have not been possible without an intense research on the stability and reliability issues. Chapter 6 reviews the most important reliability issues of GaN HEMTs for RF and microwave applications as well as power switching transistors. Failure modes and mechanisms of RF AlGaN/GaN and InAlN/GaN HEMTs are reviewed, focusing on gate-edge, hot electrons, and hot phonons related failure modes and thermal effects. For power switching devices, the effect of GaN buffer carbon doping on dynamic on-state resistance and time-dependent dielectric breakdown of the buffer are described.
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Atomic and Electronic Structure of Interfaces in Materials Systems for Future Semiconductor Devices

Atomic and Electronic Structure of Interfaces in Materials Systems for Future Semiconductor Devices

the luminescent efficiency [37]. Those GaAs films, grown on the SiGe virtual substrates, in their turn allowed the construction of working optical links, consisting of a GaAs PIN-LED as the light source, a waveguide and a GaAs PIN detector diode. Silicon-based heterostructures with high electron and hole mobilities have come a long way from the discovery of strain as a new and essential parameter for band structure engineering and the subsequent demonstration of quite rudimentary modulation doping effects, to the present state of electron and hole mobilities, which surpass those achieved in the Si/SiO 2 material combination by almost an order of magnitude. This development allows now not only the production of such devices as heterojunction bipolar transistors, modulation-doped field effect transistors, resonant tunneling diode, and photodetectors, but also the performance of experiments that were for a long time an exclusive domain of III–V materials.
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Semiconductor Devices and Electronic World

Semiconductor Devices and Electronic World

3. RESULT AND DISCUSSION One of the noteworthy things about this field, as in many other areas of technology, is how little the fundamental principles changes over time. Systems are incredibly smaller, current speeds of operation are truly remarkable, and new gadgets surface every day, leaving us to wonder where technology is taking us. However, if we take a moment to consider that the majority of all the devices in use were invented decades ago and that design techniques appearing in texts as far back as the 1930s are still in use, we realize that most of what we see is primarily a steady improvement in constructions techniques, general characteristics, and application techniques rather than the development of new elements and fundamentally new designs. The result is that most of the devices discussed in this text have been around for some time, and that tests on the subject written a decade ago are still good references with content that has not changed very much. The major changes have been in the understanding of how these devices work and their full range of capabilities, and in improved methods of teaching the fundamentals associated with them. The benefit of all this to the new student of the subject is that the material in this text will, we hope, have reached a level where it is relatively easy to grasp and the information will have application for years to come.
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Carbon Nitride and Conjugated Polymer Composite Materials

Carbon Nitride and Conjugated Polymer Composite Materials

3.1. Introduction The motivating factors in the development of next generation photovoltaics are new materials and methods for the fabrication of solar devices on a large scale and at a low cost. Polymer solar cells represent a promising opportunity toward the realization of this goal for several reasons, such as high absorption coefficients that permit the use of extremely thin films, which significantly reduces the materials costs, as well as the ability to use high throughput fabrication techniques such as jet printing, spray-coating, etc. 1,2 The vast majority of polymer solar cells studied at present use fullerenes and their derivatives as the ubiquitous acceptor materials which enhance exciton dissociation in conjugated polymers upon light absorption. 3-5 The overwhelming use of fullerenes is due to their exceptional electron accepting abilities combined with efficient electron transport properties. 6,7 The resulting active layer of a polymer solar cell typically contains 50% or more of a fullerene acceptor mixed together with a donor p-type conjugated polymer in a complex fashion forming a so-called bulk heterojunction, with exciton dissociation and photoinduced charge transfer occurring on the nanoscale between the interdispersed and very finely phase segregated donor and acceptor phases. 8 Another very important role of the fullerene phase is to provide conducting pathways throughout the photoactive film to ensure efficient extraction of photogenerated carriers.
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Global Semiconductor Packaging Materials Outlook

Global Semiconductor Packaging Materials Outlook

Increased functionality in a smaller and smaller space has driven the development of CSPs, including stacked die packages and wafer level packages. An increasing number of devices are shipping in WLP. The outlook for advanced packaging remains strong, and this includes BGA, CSP (including leadframe-based), flip chip, and WLP packages. These package types have the strongest unit growth trends over the next four years. More traditional packaging technologies will see demand stagnant and, for some basic form factors, to continue to decline.

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Gallium nitride processing for high power microwave devices

Gallium nitride processing for high power microwave devices

over all o f the visible spectrum into the UV. LEDs and lasers made from the III- nitrides enable a wide range o f consumer applications such as full colour LED screens and blue laser optical disk readers, meaning that III-nitride technology (i.e. the technology associated with the growth and processing o f the III-nitrides) has seen a much larger investment than would have been the case if the only applications o f the materials were in the microwave part o f the spectrum. This important difference between the III-nitrides and SiC has meant that III-nitrides have had a much quicker development time than SiC devices, which were initially thought to be competitive with the III-nitrides in the low GHz region but will now most likely see their use restricted to very high power, low frequency switching applications.
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Supramolecular Devices and Materials

Supramolecular Devices and Materials

Previous studies have used peptide-peptide interactions to assemble artificial binding sites, 179-182 for example with helical bundles that fold to give a zinc binding site, 183 bundling of -peptides to give cadmium-binding sites 184 and -sheet amyloids that bind zinc metal ions. 185 Despite successes using this strategy, the use of peptide-peptide interactions for assembly still requires good knowledge of structure-sequence relationships, 186 a grand challenge in itself, and the components for assembly are themselves potentially bioactive. As outlined in Chapter 1, an alternative approach to the development of devices such as artificial binding sites, is the combination of non- peptidic supramolecular moieties with peptidic elements. Non-peptidic functionalities have the potential to self-assemble a peptide binding site, thereby giving a simplified version of the protein construct which is easier to synthesise than a whole protein, whilst retaining a biologically relevant, naturally encoded amino acid-based binding site.
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Electron and Ion-beam Characterization of Nitride Semiconductor Devices.

Electron and Ion-beam Characterization of Nitride Semiconductor Devices.

47 They further performed PL studies on the same samples, and concluded that polarization effects, not segregation effects, dominated the optical properties of the QWs. However, the QWs grown in this study varied from 5.2 to 17.6nm in thickness, which are rather larger than QWs used in commercially interesting devices. As the QCSE becomes much more pronounced in thick wells, it comes as no surprise that these particular devices showed QCSE dominance. By growing a thick (~100nm) InGaN layer, they were able to show a significant effect of strain on cluster In- content; clusters near the GaN/InGaN interface, where strain was highest, had significantly increased peak In contents compared to those in the relaxed part of the layer 103 . As a general result, they found that growth technique or conditions did not have a large effect on the overall In-segregation behavior. Lastly, and most interestingly, they noted both the short-range In-segregation already mentioned, and lower-intensity, longer-range fluctuations ~100s of nm in extent 103 . Later, luminescence experiment results will be discussed that show length scales consistent with this result. Other papers 104,105,106 have reported essentially the same results as those reviewed above.
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Terahertz Generation in Submicron Nitride-based Semiconductor Devices

Terahertz Generation in Submicron Nitride-based Semiconductor Devices

1.2 Streaming Regime in III-nitrides In Chapter 2, the results of a Monte Carlo simulation of III-nitride semiconductors in the streaming regime are presented. The model is used to analyze the carrier dy- namics and highly anisotropic electron distribution function due to the dominance of polar optical phonon scattering at low temperatures. The properties of the streaming regime are first defined, followed by details of the simulation method. An analytical description of the conditions for streaming are given. The transport characteristics of the average drift velocity, the average kinetic energy associated with electron motion transverse to the field, and the mean-square deviation of the longitudinal component of the electron velocity are then calculated and examined.
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Novel dilute nitride semiconductor materials for mid infrared applications

Novel dilute nitride semiconductor materials for mid infrared applications

presented in the previous chapter led to good quality InAsN in which the nitrogen can be increased up to 2.52 % N, causing an increase in the lattice mismatch and a drastic reduction of the bandgap. Emission wavelengths up to 4.5 µm were reached at low temperature and the good material quality helped the samples show strong, narrow photoluminescence up to room temperature, with reduced bandtails and weakly localised states. A double peak-feature in the luminescence of InAsN was attributed to free carrier and localised carrier recombinations. Localised states are subject to carrier de-trapping with increasing excitation power or temperature, leading to their sought- after quenching and the observed blueshift. The temperature dependence of InAsN bandgap was fitted with Varshni's equation (for various nitrogen compositions) and was shown to reduce with increasing nitrogen composition, that is a true advantage in materials for mid-infrared applications. InAsN samples showed a mirror-like surface morphology and only high nitrogen composition (2.52 %) induced cross-hatching on the surface by relaxation of the strain. The surface roughness of InAsN epilayers was shown to increase with nitrogen composition, which clarified the interpretation of the RHEED patterns observed during growth. Rapid thermal annealing favoured an increase in the luminescence intensity with limited blueshift and evidenced further the behaviour of the bandgap related-peak, but did not affect the localisation potential.
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Characterisation and modeling of Gallium nitride power semiconductor devices dynamic on state resistance

Characterisation and modeling of Gallium nitride power semiconductor devices dynamic on state resistance

From 1990 to 1992, he was a Research Asso- ciate at the University of Cambridge. In 1992, he was appointed as a Lecturer at the Newcastle Uni- versity, U.K., where his research included the design, analysis and characterisation of power semiconductor devices, resonant power conversion, and instrumen- tation. From 1998 to 2001, he managed the U.K. National Programme on Silicon Carbide electronics. In 2000, he became Reader of Power Electronics at New- castle University. In 2003, he was appointed as Rolls-Royce/RAEng Research Professor of Power Electronic Systems at the University of SheffieldIn 2006, he was a Personal Chair at the University of Nottingham, where he leads research into power semiconductor devices, power device packaging, reliability, thermal management, power module technologies, and power electronic applications.
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Characterisation and modelling of gallium nitride
power semiconductor devices dynamic on state
resistance

Characterisation and modelling of gallium nitride power semiconductor devices dynamic on state resistance

[12] D. Jin and J. Del Alamo, “Methodology for the Study of Dynamic ON-Resistance in High-Voltage GaN Field-Effect Transistors,” Electron Devices, IEEE Transactions on, vol. 60, pp. 3190–3196, Oct 2013. [13] G. Cao, A. Ansari, and H.-J. Kim, “A New Measurement Circuit to Evaluate Current Collapse Effect of GaN HEMTs Under Practical Conditions,” Instrumentation and Measurement, IEEE Transactions on, vol. 64, pp. 1977–1986, July 2015.

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Formation of Embedded Nitride Semiconductor Nanocrystals.

Formation of Embedded Nitride Semiconductor Nanocrystals.

6.2 Suggestions for Future Work In Chapters 3-5, we presented methods for controlling the size, crystalline phase, and lateral position of InN and GaN nanocrystals. Embedded GaN or InN nanocrystals were formed via ion implantation followed by thermal annealing. Nanocrystals formed via this method have dimensions (3-5 nm) that are comparable to the sizes achievable with colloidal growth, but are embedded in a protective host matrix and can be laterally spaced, comparable to epitaxial growth methods. However, further work is needed to examine the effect of the nanostructure on the physical properties of the materials. In the following sections, we will discuss three suggestions for future work that will relate the structure of the materials to device performance and present a method of multi- dimensional fabrication. First, we will discuss thermal conductivity measurements of InN and GaN nanostructures. Then, we will discuss photoluminescence of InN and GaN nanocrystals. Finally, we will present a process of extending directed matrix seeding to multiple dimensions.
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Rare-Earth Doped Wide Bandgap Oxide Semiconductor Materials and Devices

Rare-Earth Doped Wide Bandgap Oxide Semiconductor Materials and Devices

may prove particularly interesting for high-power lasers as the presence of substitutional Eu 3+ ions did not alter the local structure of the host, which suggests that the thermal properties of Gd 2 O 3 may not substantially degrade with doping. Europium doped IGZO thin films have been developed and integrated into a working active matrix pixel circuit. Future work in this area should focus on the fabrication of faster TFTs, brighter phosphor materials and device design. Faster TFTs have been fabricated using smaller channel dimensions. This improved transient response has been demonstrated by an IGZO ring oscillator circuit operating at over 2 MHz. However, tradeoffs between device speed and current-carrying capacity must be considered. The high channel mobility of IGZO TFTs is beneficial in this regard by improving both the saturation current density and transient response of a TFT with a given size.
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Rhombohedral cubic semiconductor materials on trigonal substrate with single crystal properties and devices based on such materials

Rhombohedral cubic semiconductor materials on trigonal substrate with single crystal properties and devices based on such materials

A semiconductor material comprising rhombohedrally aligned cubic semiconductor material (group IV, III-V, and II-VI), and alloys thereof, in diamond structure or cubic zinc- blende str[r]

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DEVELOPMENTS & TRENDS IN FEOL MATERIALS FOR ADVANCED SEMICONDUCTOR DEVICES Michael Corbett Semicon Taiwan2015

DEVELOPMENTS & TRENDS IN FEOL MATERIALS FOR ADVANCED SEMICONDUCTOR DEVICES Michael Corbett Semicon Taiwan2015

Linx Consulting 1. We help our clients to succeed by creating know ledge and developing unique insights at the intersection of electronic thin film processes and the chemicals industry 2. The know ledge is based on a core understanding of the semiconductor device technology; manufacturing processes and roadmaps; and the structural industry dynamics

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