The Experts below are selected from a list of 11934 Experts worldwide ranked by ideXlab platform
M R Krames - One of the best experts on this subject based on the ideXlab platform.
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history of Gallium Nitride based light emitting diodes for illumination
2013Co-Authors: Shuji Nakamura, M R KramesAbstract:The history of development for Gallium-Nitride-based light-emitting diodes (LEDs) is reviewed. We identify two broad developments in GaN-based LED technology: first, the key breakthroughs that enabled the development of GaN-based devices on foreign substrates like sapphire (first-generation LEDs), and, second, a new wave of devices benefiting from developments in GaN substrate manufacturing, which has led to native bulk-GaN-based LEDs with unprecedented performance characteristics that portend a disruptive shift in LED output power density and the corresponding cost of generating light.
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a dual wavelength indium Gallium Nitride quantum well light emitting diode
2001Co-Authors: Ilker Ozden, E Makarona, A V Nurmikko, T Takeuchi, M R KramesAbstract:We have designed and implemented a monolithic, dual-wavelength blue/green light emitting diode (LED) consisting of two active indium Gallium Nitride/Gallium Nitride (InGaN/GaN) multiple-quantum-well segments. The segments are part of a single vertical epitaxial structure in which a p++/n++ InGaN/GaN tunnel junction is inserted between the LEDs, emitting in this proof-of-concept device at 470 nm and 535 nm, respectively. The device has been operated as a three-terminal device with independent electrical control of each LEDs to a nanosecond time scale.
Johan Strydom - One of the best experts on this subject based on the ideXlab platform.
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Evaluation of Gallium Nitride transistors in high frequency resonant and soft-switching DC-DC Converters
2015Co-Authors: David Reusch, Johan StrydomAbstract:The emergence of Gallium Nitride (GaN)-based power devices offers the potential to achieve higher efficiencies and higher switching frequencies than possible with mature silicon (Si) power MOSFETs. In this paper, we will evaluate the ability of Gallium Nitride transistors to improve efficiency and output power density in high frequency resonant and soft-switching applications. To experimentally verify the benefits of replacing Si MOSFETs with enhancement mode GaN transistors (eGaNFETs) in a high frequency resonant converter, 48-12 V unregulated isolated bus converter prototypes operating at a switching frequency of 1.2 MHz and an output power of up to 400 W are compared using Si and GaN power devices.
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evaluation of Gallium Nitride transistors in high frequency resonant and soft switching dc dc converters
2014Co-Authors: David Reusch, Johan StrydomAbstract:The emergence of Gallium Nitride (GaN) based power devices offers the potential to achieve higher efficiencies and higher switching frequencies than possible with aging silicon (Si) power MOSFETs. In this paper, we will evaluate the ability of Gallium Nitride transistors to improve efficiency and output power density in high frequency resonant and soft-switching applications. To experimentally verify the benefits of replacing Si MOSFETs with enhancement mode GaN transistors (eGaN®FETs) in a high frequency resonant converter, 48 V to 12 V unregulated isolated bus converter prototypes operating at a switching frequency of 1.2 MHz and an output power of up to 400W are compared using Si and GaN power devices.
David Reusch - One of the best experts on this subject based on the ideXlab platform.
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Evaluation of Gallium Nitride transistors in high frequency resonant and soft-switching DC-DC Converters
2015Co-Authors: David Reusch, Johan StrydomAbstract:The emergence of Gallium Nitride (GaN)-based power devices offers the potential to achieve higher efficiencies and higher switching frequencies than possible with mature silicon (Si) power MOSFETs. In this paper, we will evaluate the ability of Gallium Nitride transistors to improve efficiency and output power density in high frequency resonant and soft-switching applications. To experimentally verify the benefits of replacing Si MOSFETs with enhancement mode GaN transistors (eGaNFETs) in a high frequency resonant converter, 48-12 V unregulated isolated bus converter prototypes operating at a switching frequency of 1.2 MHz and an output power of up to 400 W are compared using Si and GaN power devices.
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evaluation of Gallium Nitride transistors in high frequency resonant and soft switching dc dc converters
2014Co-Authors: David Reusch, Johan StrydomAbstract:The emergence of Gallium Nitride (GaN) based power devices offers the potential to achieve higher efficiencies and higher switching frequencies than possible with aging silicon (Si) power MOSFETs. In this paper, we will evaluate the ability of Gallium Nitride transistors to improve efficiency and output power density in high frequency resonant and soft-switching applications. To experimentally verify the benefits of replacing Si MOSFETs with enhancement mode GaN transistors (eGaN®FETs) in a high frequency resonant converter, 48 V to 12 V unregulated isolated bus converter prototypes operating at a switching frequency of 1.2 MHz and an output power of up to 400W are compared using Si and GaN power devices.
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Gallium Nitride based 3d integrated non isolated point of load module
2012Co-Authors: David Reusch, David Gilham, F C LeeAbstract:The introduction of Gallium Nitride (GaN) based power devices offers the potential to achieve higher efficiency and higher switching frequencies than possible with Silicon MOSFET's. This paper will discuss the GaN device characteristics, packaging impact on performance, gate driving methods, and the integration possibilities using GaN technology. The final demonstration being an integrated 3D point of load (POL) converter operating at a switching frequency of 2MHz for a 12V to 1.2V buck converter with a full load current of 20A. This 3D converter employs a low profile low temperature co-fired ceramic (LTCC) inductor and can achieve a full load efficiency of 83% and a power density of 750W/in3 which doubles the power density of current integrated POL converters on the market today.
Hong Guo - One of the best experts on this subject based on the ideXlab platform.
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tuning the surface fermi level on p type Gallium Nitride nanowires for efficient overall water splitting
2014Co-Authors: M G Kibria, Songrui Zhao, Faqrul A Chowdhury, Qi Wang, Hieu Pham Trung Nguyen, M L Trudeau, Hong GuoAbstract:One of the obstacles in implementing solar water splitting is the requirement for materials with high internal quantum efficiency. Here, the authors investigate the effects of magnesium doping on the Fermi levels of Gallium Nitride nanowires, and tune this value to maximize redox efficiency.
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tuning the surface fermi level on p type Gallium Nitride nanowires for efficient overall water splitting
2014Co-Authors: M G Kibria, Songrui Zhao, Faqrul A Chowdhury, Qi Wang, Hieu Pham Trung Nguyen, M L Trudeau, Hong GuoAbstract:Solar water splitting is one of the key steps in artificial photosynthesis for future carbon-neutral, storable and sustainable source of energy. Here we show that one of the major obstacles for achieving efficient and stable overall water splitting over the emerging nanostructured photocatalyst is directly related to the uncontrolled surface charge properties. By tuning the Fermi level on the nonpolar surfaces of Gallium Nitride nanowire arrays, we demonstrate that the quantum efficiency can be enhanced by more than two orders of magnitude. The internal quantum efficiency and activity on p-type Gallium Nitride nanowires can reach ~51% and ~4.0 mol hydrogen h(-1) g(-1), respectively. The nanowires remain virtually unchanged after over 50,000 μmol gas (hydrogen and oxygen) is produced, which is more than 10,000 times the amount of photocatalyst itself (~4.6 μmol). The essential role of Fermi-level tuning in balancing redox reactions and in enhancing the efficiency and stability is also elucidated.
Dirk Englund - One of the best experts on this subject based on the ideXlab platform.
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bright room temperature single photon emission from defects in Gallium Nitride
2017Co-Authors: Amanuel M. Berhane, Kwang Yong Jeong, Zoltán Bodrog, Saskia Fiedler, Ádám Gali, Tim Schröder, Noelia Vico Trivino, Milos Toth, Tomas Palacios, Dirk EnglundAbstract:Room-temperature quantum emitters in Gallium Nitride (GaN) are reported. The emitters originate from cubic inclusions in hexagonal lattice and exhibit narrowband luminescence in the red spectral range. The sources are found in different GaN substrates, and therefore are promising for scalable quantum technologies.
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Bright Room-Temperature Single-Photon Emission from Defects in Gallium Nitride
2017Co-Authors: Amanuel M. Berhane, Kwang Yong Jeong, Zoltán Bodrog, Saskia Fiedler, Ádám Gali, Tim Schröder, Noelia Vico Trivino, Milos Toth, Tomas Palacios, Dirk EnglundAbstract:Single photon emitters play a central role in many photonic quantum technologies. A promising class of single photon emitters consists of atomic color centers in wide-bandgap crystals, such as diamond silicon carbide and hexagonal boron Nitride. However, it is currently not possible to grow these materials as sub-micron thick films on low-refractive index substrates, which is necessary for mature photonic integrated circuit technologies. Hence, there is great interest in identifying quantum emitters in technologically mature semiconductors that are compatible with suitable heteroepitaxies. Here, we demonstrate robust single photon emitters based on defects in Gallium Nitride (GaN), the most established and well understood semiconductor that can emit light over the entire visible spectrum. We show that the emitters have excellent photophysical properties including a brightness in excess of 500x10^3 counts/s. We further show that the emitters can be found in a variety of GaN wafers, thus offering reliable and scalable platform for further technological development. We propose a theoretical model to explain the origin of these emitters based on cubic inclusions in hexagonal Gallium Nitride. Our results constitute a feasible path to scalable, integrated on-chip quantum technologies based on GaN.
