Light Emitting Diodes And Photodetectors Based On Iii-nitride And Colloidal Quantum Dot Materials PDF Download
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Author: Zhenyu Jiang
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
In this work, we first proposed the tandem architecture for solution-processed near infrared PbSe colloidal quantum dot (CQD)-based photodetectors to address the high dark current issue. The tandem architecture not only absorbs the virtue of tandem solar cell by means of efficient photon-to-current conversion, but also functions as the effective barrier that can block the leakage current. More than three orders of magnitude reduction in dark current has been observed, along with an elevated photocurrent. The low temperature current-voltage characteristics revealed that the tandem architecture posed a high energy barrier which effectively blocks the dark current. Our results suggest that tandem architecture can be employed to developing high-performance solution-processed photodetector. The application of tandem photodetectors was further extended to sensors on flexible substrates where little study has been reported to date. Our results on flexible tandem photodetectors validate the high efficiency and detectivity of the tandem architecture. Two different bending states have been studied which revealed the small critical bend radii of ~8mm and ~3mm for tensile and compressive bending, respectively. The photodetector performance remains stable under mechanical stress which offers great potential of CQDs-based tandem photodetectors for flexible device applications. Furthermore, we have demonstrated the chip level integration of flip-chip light emitting diode (LED) with current rectifying GaN Schottky barrier diodes constituting the Wheatstone bridge circuitry for alternating current (AC) driving. The flip-chip LED scheme offers better p-contact, high light extraction efficiency and fast heat dissipation. The reflectance and turn-on voltage were investigated under various p-contact annealing conditions. The flip-chip alternating current LEDs (ACLEDs) demonstrated more than ~23% improvement in terms of energy conversion efficiency over top-emissive ACLEDs and offer the potential of using such device for high brightness, high power, high efficiency and high reliability solid state lighting applications. Finally, built on our studies of LEDs and photodetectors, and of chip level integration of LEDs and GaN Schottky barrier diodes. we, for the first time, proposed the integration of visible LEDs and UV GaN photodetectors for bi-directional optical wireless communication (OWC) applications. The LEDs function as transmitters to emit visible light signal whereas the photodetectors as receivers to collect UV signals. The crosstalk can be neglected due to the superior visible-blind property of GaN UV photodetector. The experimental results demonstrated that the LEDs and photodetectors can work together efficiently which opens up a new avenue for using such device for bi-directional OWC applications.
Author: Zhenyu Jiang
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
In this work, we first proposed the tandem architecture for solution-processed near infrared PbSe colloidal quantum dot (CQD)-based photodetectors to address the high dark current issue. The tandem architecture not only absorbs the virtue of tandem solar cell by means of efficient photon-to-current conversion, but also functions as the effective barrier that can block the leakage current. More than three orders of magnitude reduction in dark current has been observed, along with an elevated photocurrent. The low temperature current-voltage characteristics revealed that the tandem architecture posed a high energy barrier which effectively blocks the dark current. Our results suggest that tandem architecture can be employed to developing high-performance solution-processed photodetector. The application of tandem photodetectors was further extended to sensors on flexible substrates where little study has been reported to date. Our results on flexible tandem photodetectors validate the high efficiency and detectivity of the tandem architecture. Two different bending states have been studied which revealed the small critical bend radii of ~8mm and ~3mm for tensile and compressive bending, respectively. The photodetector performance remains stable under mechanical stress which offers great potential of CQDs-based tandem photodetectors for flexible device applications. Furthermore, we have demonstrated the chip level integration of flip-chip light emitting diode (LED) with current rectifying GaN Schottky barrier diodes constituting the Wheatstone bridge circuitry for alternating current (AC) driving. The flip-chip LED scheme offers better p-contact, high light extraction efficiency and fast heat dissipation. The reflectance and turn-on voltage were investigated under various p-contact annealing conditions. The flip-chip alternating current LEDs (ACLEDs) demonstrated more than ~23% improvement in terms of energy conversion efficiency over top-emissive ACLEDs and offer the potential of using such device for high brightness, high power, high efficiency and high reliability solid state lighting applications. Finally, built on our studies of LEDs and photodetectors, and of chip level integration of LEDs and GaN Schottky barrier diodes. we, for the first time, proposed the integration of visible LEDs and UV GaN photodetectors for bi-directional optical wireless communication (OWC) applications. The LEDs function as transmitters to emit visible light signal whereas the photodetectors as receivers to collect UV signals. The crosstalk can be neglected due to the superior visible-blind property of GaN UV photodetector. The experimental results demonstrated that the LEDs and photodetectors can work together efficiently which opens up a new avenue for using such device for bi-directional OWC applications.
Author: Jinmin Li
Publisher: Springer Nature
ISBN: 9811579490
Category : Technology & Engineering
Languages : en
Pages : 295
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Book Description
The book provides an overview of III-nitride-material-based light-emitting diode (LED) technology, from the basic material physics to the latest advances in the field, such as homoepitaxy and heteroepitaxy of the materials on different substrates. It also includes the latest advances in the field, such as approaches to improve quantum efficiency and reliability as well as novel structured LEDs. It explores the concept of material growth, chip structure, packaging, reliability and application of LEDs. With spectra coverage from ultraviolet (UV) to entire visible light wavelength, the III-nitride-material-based LEDs have a broad application potential, and are not just limited to illumination. These novel applications, such as health & medical, visible light communications, fishery and horticulture, are also discussed in the book.
Author: Gerasimos Konstantatos
Publisher: Cambridge University Press
ISBN: 0521198267
Category : Science
Languages : en
Pages : 329
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Book Description
Captures the most up-to-date research in the field, written in an accessible style by the world's leading experts.
Author: Xin Tong
Publisher: Springer Nature
ISBN: 3030742709
Category : Technology & Engineering
Languages : en
Pages : 319
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Book Description
This book presents a comprehensive overview of state-of-the-art quantum dot photodetectors, including device fabrication technologies, optical engineering/manipulation strategies, and emerging photodetectors with building blocks of novel quantum dots (e.g. perovskite) as well as their hybrid structured (e.g. 0D/2D) materials. Semiconductor quantum dots have attracted much attention due to their unique quantum confinement effect, which allows for the facile tuning of optical properties that are promising for next-generation optoelectronic applications. Among these remarkable properties are large absorption coefficient, high photosensitivity, and tunable optical spectrum from ultraviolet/visible to infrared region, all of which are very attractive and favorable for photodetection applications. The book covers both fundamental and frontier research in order to stimulate readers' interests in developing novel ideas for semiconductor photodetectors at the center of future developments in materials science, nanofabrication technology and device commercialization. The book provides a knowledge sharing platform and can be used as a reference for researchers working in the fields of photonics, materials science, and nanodevices.
Author: Mohamed Henini
Publisher: Elsevier Science
ISBN: 9780080463254
Category : Technology & Engineering
Languages : en
Pages : 841
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Book Description
In 1969, Leo Esaki (1973 Nobel Laureate) and Ray Tsu from IBM, USA, proposed research on “man-made crystals” using a semiconductor superlattice (a semiconductor structure comprising several alternating ultra-thin layers of semiconductor materials with different properties). This invention was perhaps the first proposal to advocate the engineering of a new semiconductor material, and triggered a wide spectrum of experimental and theoretical investigations. However, the study of what are now called low dimensional structures (LDS) began in the late 1970's when sufficiently thin epitaxial layers were first produced following developments in the technology of epitaxial growth of semiconductors, mainly pioneered in industrial laboratories for device purposes. The LDS are materials structures whose dimensions are comparable with inter-atomic distances in solids (i.e. nanometre, nm). Their electronic properties are significantly different from the same material in bulk form. These properties are changed by quantum effects. At the inception of their investigation it was already clear that such structures were of great scientific interest and excitement and their novel properties caused by quantum effects offered potential for application in new devices. Moreover these complex LDS offer device engineers new design opportunities for tailor-made new generation electronic devices. The LDS could be considered as a new branch of condensed matter physics because of the large variety of possible structures and the changes in the physical processes. One of the promising fabrication methods to produce and study structures with a dimension less than two such as quantum wires and quantum dots, in order to realise novel devices that make use of low-dimensional confinement effects, is self-organisation. Self-assembled nanostructured materials offer a number of advantages over conventional material technologies in a wide-range of sectors. Clearly, future research work on self-assembled nanostructures will connect diverse areas of material science, physics, chemistry, electronics and optoelectronics. Key Features: - Contributors are world leaders in the field - Brings together all the factors which are essential in self-organisation of quantum nanostructures - Reviews the current status of research and development in self-organised nanostructured materials - Provides a ready source of information on a wide range of topics - Useful to any scientist who is involved in nanotechnology - Excellent starting point for workers entering the field - Serves as an excellent reference manual
Author: Feng Gao
Publisher: Elsevier
ISBN: 0128136472
Category : Technology & Engineering
Languages : en
Pages : 550
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Book Description
Advanced Nanomaterials for Solar Cells and Light Emitting Diodes discusses the importance of nanomaterials as the active layers in solar cells and light emitting diodes (LEDs), along with the progress of nanomaterials as the electron and hole transporting layers. Specifically, the book reviews the use of nano-morphology of polymers, small molecules, and the organic-inorganic perovskites as the active layers in solar cells and LEDs. The design, fabrication and properties of metal-oxide-based nano-structures as electron and hole transporting layers are also reviewed. In addition, the development of plasmonic nanomaterials for solar cells and LEDs is discussed. Each topic in this book includes an overview of the materials system from principles to process. The advantages, disadvantages and related methodologies are highlighted. The book includes applications based on materials and emphasize how to improve the performance of solar cells and LEDs by the materials design, with a focus on nanomaterials. Provides latest research on nanostructured materials including small molecules, polymers, organic-inorganic perovskites, and many other relevant materials systems for solar cells and LEDs Addresses each promising materials system from principles to process, detailing the advantages and disadvantages of the most relevant methods of processing and fabrication Looks ahead to most likely techniques to improve performance of solar cells and light emitting diodes
Author: Vladimir Lesnyak
Publisher: Frontiers Media SA
ISBN: 2889632695
Category :
Languages : en
Pages : 110
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Book Description
Author: Jason Paul Clifford
Publisher:
ISBN: 9780494579725
Category :
Languages : en
Pages : 398
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Book Description
Herein, we report the first solution-processed broadband photodetectors to break the past compromise between sensitivity and speed of response. Specifically, we report photodiodes having normalized detectivity (D*) > 1012 Jones and a 3dB bandwidth of > 2.9 MHz. This finding represents a 170,000 fold improvement in response speed over the most sensitive colloidal quantum dot (CQD) photodetector reported1 and a 100,000 fold improvement in sensitivity over the fastest CQD photodetector reported2.Efficient, sensitive semiconductor photodiodes are based on two fundamental characteristics: a large built-in potential that separates photogenerated charge carriers and minimizes internal noise generation, and high semiconductor conductivity for efficient collection of photogenerated charge. Schottky barriers to CQD films were developed to provide high, uniform built-in potentials. A multi-step CQD ligand exchange procedure was developed to allow deposition of tightly packed films of CQDs with high mobility and sufficiently well-passivated surfaces to form high-quality metallurgical junctions.The temporal response of the CQD photodiodes showed separate drift and diffusion components. Combined with detailed measurements of the Schottky barrier, these characteristics provided the physical basis for a numerical model of device operation. Based on this understanding, devices that excluded the slow diffusive component were fabricated, exploiting only the sub-microsecond field-driven transient to achieve MHz response bandwidth.At the outset of this study, sensitive, solution-processed IR photodetectors were severely limited by low response speeds1. Much faster response speeds had been demonstrated by solution-processed photodetectors operating in the visible3, but these devices offered no benefits for extending the spectral sensitivity of silicon. No available solution-processed photodetector combined high sensitivity, high operating speed, and response to illumination across the UV, visible and IR.We developed a fast, sensitive, solution-processed photodetector based on a photodiode formed by a Schottky barrier to a CQD film. Previous attempts to form sensitive photodetectors based on CQD photodiodes had demonstrated low quantum efficiencies that limited sensitivity4,5.These devices are the first to combine megahertz-bandwidth, high sensitivity, and spectral-tunability in photodetectors based on semiconducting CQDs. Record performance is achieved through advances in materials and device architecture based on a detailed understanding the physical mechanisms underlying the operation of CQD photodiodes.
Author: Ye Zhou
Publisher: Springer Nature
ISBN: 9811566372
Category : Technology & Engineering
Languages : en
Pages : 374
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Book Description
This book addresses perovskite quantum dots, discussing their unique properties, synthesis, and applications in nanoscale optoelectronic and photonic devices, as well as the challenges and possible solutions in the context of device design and the prospects for commercial applications. It particularly focuses on the luminescent properties, which differ from those of the corresponding quantum dots materials, such as multicolor emission, fluorescence narrowing, and tunable and switchable emissions from doped nanostructures. The book first describes the characterization and fabrication of perovskite quantum dots. It also provides detailed methods for analyzing the electrical and optical properties, and demonstrates promising applications of perovskite quantum dots. Furthermore, it presents a series of optoelectronic and photonic devices based on functional perovskite quantum dots, and explains the incorporation of perovskite quantum dots in semiconductor devices and their effect of the performance. It also explores the challenges related to optoelectronic devices, as well as possible strategies to promote their commercialization. As such, this book is a valuable resource for graduate students and researchers in the field of solid-state materials and electronics wanting to gain a better understanding of the characteristics of quantum dots, and the fundamental optoelectronic properties and operation mechanisms of the latest perovskite quantum dot-based devices.
Author: Zhe Chuan Feng
Publisher: World Scientific
ISBN: 1908979941
Category : Technology & Engineering
Languages : en
Pages : 442
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Book Description
III-Nitride semiconductor materials — (Al, In, Ga)N — are excellent wide band gap semiconductors very suitable for modern electronic and optoelectronic applications. Remarkable breakthroughs have been achieved recently, and current knowledge and data published have to be modified and upgraded. This book presents the new developments and achievements in the field.Written by renowned experts, the review chapters in this book cover the most important topics and achievements in recent years, discuss progress made by different groups, and suggest future directions. Each chapter also describes the basis of theory or experiment.The III-Nitride-based industry is building up and new economic developments from these materials are promising. It is expected that III-Nitride-based LEDs may replace traditional light bulbs to realize a revolution in lighting. This book is a valuable source of information for engineers, scientists and students working towards such goals./a
