Optical and Magneto-Optical Studies of Rare Earth Doped Gallium Nitride PDF Download
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Author: Nathaniel T. Woodward
Publisher:
ISBN: 9781124657868
Category :
Languages : en
Pages : 186
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Book Description
Understanding the excitation mechanisms of rare earth ions in materials used for optoelectronic applications is key to achieving more efficient and versatile devices based on these material systems. Of particular importance to applications involving light emission is identifying the most efficient excitation pathways of the rare earth dopant. Such a task is complicated by the presence of multiple rare earth environments often observed in such materials which have the potential to have drastically different relative excitation characteristics. Furthermore, due to the recent interest in dilute ferromagnetic semiconductors, the three systems studied have shown to all exhibit room temperature ferromagnetic behavior. This has led to several questions on the mechanism behind the interaction of ions which cause the ferromagnetism, and by which our spectroscopic techniques allow for unique investigations.
Author: Nathaniel T. Woodward
Publisher:
ISBN: 9781124657868
Category :
Languages : en
Pages : 186
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Book Description
Understanding the excitation mechanisms of rare earth ions in materials used for optoelectronic applications is key to achieving more efficient and versatile devices based on these material systems. Of particular importance to applications involving light emission is identifying the most efficient excitation pathways of the rare earth dopant. Such a task is complicated by the presence of multiple rare earth environments often observed in such materials which have the potential to have drastically different relative excitation characteristics. Furthermore, due to the recent interest in dilute ferromagnetic semiconductors, the three systems studied have shown to all exhibit room temperature ferromagnetic behavior. This has led to several questions on the mechanism behind the interaction of ions which cause the ferromagnetism, and by which our spectroscopic techniques allow for unique investigations.
Author: Brandon Mitchell
Publisher:
ISBN: 9781321224597
Category :
Languages : en
Pages : 222
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Book Description
Wide band gap semiconductors doped with rare earth ions (RE) have shown great potential for applications in optoelectronics, photonics, and spintronics. The 1.54mum Erbium (Er) emission has been extensively utilized in optical fiber communications, and Europium (Eu) is commonly used as a red color component for LEDs and fluorescence lamps. For the realization of spintronic-type devices, a dilutely doped semiconductor that exhibits room temperature ferromagnetic behavior would be desirable. Such behavior has been observed in GaN:Er. Furthermore, it was demonstrated that strain may play an important role in the control of this ferromagnetism; however, this requires further investigation.
Author: Uygun V. Valiev
Publisher: Scientific Research Publishing, Inc. USA
ISBN: 1618960547
Category : Science
Languages : en
Pages : 146
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Book Description
A comparison of theory with experiment is made for rare-earth compounds with garnet structure and orthoaluminate whose optical, magnetic and magnetooptical features have been studied sufficiently well by now.
Author: Tiju Thomas
Publisher:
ISBN:
Category :
Languages : en
Pages : 158
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Book Description
Gallium Nitride is a III-V compound semiconductor that has attracted a lot of interest among both applied and basic researchers because of its potential applications in optoelectronic, high power and high frequency devices. However, many questions about the material remain unanswered. In this thesis, we will present our investigation of GaN. We will first describe an ammonothermal method for the synthesis of undoped and rare earth doped GaN powders. Using careful observations and calculations, we show that the powder growth is primarily a liquid phase phenomenon. We also present a chemical method to achieve luminescence enhancement in ammonothermally grown Eu:GaN powders. Based on arguments drawn from the surface chemistry and XRD of these samples, we conclude that elimination of dark mixed oxides from the powder results in the observed luminescence enhancement. We also demonstrate a nano Eu:GaN synthesis process using a simple mechanical topdown method. The optical properties of nano Eu:GaN prepared in this manner is comparable to that of the bulk material. Based on a similar mechanical process we synthesized nano Er:GaN powders that emit in the C band (1.55 m). The mechanism involved in the luminescence of rare earth doped GaN is investigated using thermal quenching and high pressure studies. Our results suggest that an exciton bound to rare earth structured isovalent impurity (RESI) is responsible for luminescence in these materials. Luminescence quenching and pressure dependent photoluminescence enhancement in RE:GaN can be explained based on this model. Our results clearly suggest that thermal quenching can be undone by application of pressure. These powders are discovered to be fairly radiation hard as well. In the last section of this thesis, we will present an electrophoretic technique to deposit nano GaN on a fluorine doped tin oxide coated glass substrate. The technique can be easily adapted to grow layered structures that can find application in optical fibers and as a laser gain medium. Preliminary results for highly densified GaN ceramic obtained using a hot-press process are discussed. These results suggest that further densification is necessary for achieving a completely transparent GaN ceramic made out of ammonothermally synthesized GaN powders.
Author: Philip Aldam Shields
Publisher:
ISBN:
Category : Gallium compounds
Languages : en
Pages : 324
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Book Description
Author: Stephen J. Pearton
Publisher: Springer Science & Business Media
ISBN: 1846283590
Category : Technology & Engineering
Languages : en
Pages : 383
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Book Description
Semiconductor spintronics is expected to lead to a new generation of transistors, lasers and integrated magnetic sensors that can be used to create ultra-low power, high speed memory, logic and photonic devices. Useful spintronic devices will need materials with practical magnetic ordering temperatures and current research points to gallium and aluminium nitride magnetic superconductors as having great potential. This book details current research into the properties of III-nitride semiconductors and their usefulness in novel devices such as spin-polarized light emitters, spin field effect transistors, integrated sensors and high temperature electronics. Written by three leading researchers in nitride semiconductors, the book provides an excellent introduction to gallium nitride technology and will be of interest to all reseachers and industrial practitioners wishing to keep up to date with developments that may lead to the next generation of transistors, lasers and integrated magnetic sensors.
Author: Wang Rui
Publisher:
ISBN:
Category :
Languages : en
Pages : 130
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Book Description
Rare Earth (RE) doped III-nitrides are being widely investigated for potential applications in optical communication and displays, due to the wide and direct energy bandgap of GaN resulting in low thermal quenching of RE ion sharp emission from ultraviolet (UV) through visible to infrared (IR) region. The UC Nanolab has been conducting RE doped GaN research for more than 10 years and many achievements were obtained, ranging from material growth to device fabrication. This dissertation studied RE emission in GaN material, focusing on the effects of electronic impurity (Si) co-doping on RE luminescence. Advanced RE doped GaN electroluminescent devices (ELDs) were also designed and fabricated. Detailed device characterization was carried out and the effect of co-dopant was investigated. Eu-doped GaN thin films were grown on sapphire wafers by molecular beam epitaxy (MBE) technique and the growth conditions were optimized for the strongest Eu luminescence. It was found that GaN thin film quality and Eu doping concentration mutually affected Eu luminescence. High quality GaN:Eu thin films were grown under Ga rich condition (III/V>1), but the strongest Eu luminescence was obtained under slightly N rich condition (III/V1). The optimum Eu doping concentration is ~0.1-1.0at.%, depending on the GaN:Eu thin film quality. Higher growth temperature (750°C) was also found to enhance Eu luminescence intensity (~10x) and efficiency (~30x). The effect of Si co-doping in GaN:RE thin films was investigated. Eu photoluminescence (PL) was enhanced ~5-10x by moderate Si co-doping (~0.05at.%) mostly due to the increase of Eu PL lifetime, but decreased very fast at high Si co-doping concentration (>0.08at.%). The increase of Eu PL lifetime is possibly due to the incorporation of Si uniformly distributing Eu ions and shielding Eu-Eu interactions. Combined with the increase in excitation cross section and carrier flux, there is a significant enhancement on Eu PL intensity. The electrical properties of GaN:RE thin films were changed from high resistive to weakly n-type due to increased electron concentration introduced by Si co-doping. GaN:RE ELDs were fabricated and the electrical and optical properties were studied by I-V and electroluminescence (EL) measurements. A hetero-junction PIN structure was designed on n-GaN:Si/GaN:RE/p-Si, employing p-Si substrates as p-type conductive layer. RE ions EL emission was found to be much stronger under forward bias than under reverse bias. The Si co-doping was also studied in GaN:RE ELDs. It was found that Er EL had strong visible & IR emission under forward bias, while there is little or no emission under reverse bias. A pn hetero-junction structure formed between p-Si and n-GaN:(Si, Er) layers was proposed to be responsible for the emission control. GaN:(Si, Eu) AC thin film ELDs were also fabricated and shown that the Si co-doping increased the Eu ions emission intensity and efficiency.
Author: Volkmar Dierolf
Publisher: Woodhead Publishing
ISBN: 008100060X
Category : Science
Languages : en
Pages : 472
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Book Description
Rare Earth and Transition Metal Doping of Semiconductor Material explores traditional semiconductor devices that are based on control of the electron’s electric charge. This book looks at the semiconductor materials used for spintronics applications, in particular focusing on wide band-gap semiconductors doped with transition metals and rare earths. These materials are of particular commercial interest because their spin can be controlled at room temperature, a clear opposition to the most previous research on Gallium Arsenide, which allowed for control of spins at supercold temperatures. Part One of the book explains the theory of magnetism in semiconductors, while Part Two covers the growth of semiconductors for spintronics. Finally, Part Three looks at the characterization and properties of semiconductors for spintronics, with Part Four exploring the devices and the future direction of spintronics. Examines materials which are of commercial interest for producing smaller, faster, and more power-efficient computers and other devices Analyzes the theory behind magnetism in semiconductors and the growth of semiconductors for spintronics Details the properties of semiconductors for spintronics
Author:
Publisher:
ISBN:
Category : Chemistry
Languages : en
Pages : 2540
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Book Description
Author: Gerald T. Thaler
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
A prototype spintronic device, (the spin polarized light emitting diode) was prepared. Unfortunately, no spin polarized emission was detected from the LED. The lack of polarization was traced to a high spin relaxation rate in the InGaN LED quantum wells.
