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Showing papers on "Diode published in 2003"


01 Jan 2003
TL;DR: In this article, a monolithic terahertz injection laser that is based on interminiband transitions in the conduction band of a semiconductor (GaAs/AlGaAs) heterostructure is presented.
Abstract: Semiconductor devices have become indispensable for generating electromagnetic radiation in everyday applications. Visible and infrared diode lasers are at the core of information technology, and at the other end of the spectrum, microwave and radio-frequency emitters enable wireless communications. But the terahertz region (1-10 THz; 1 THz = 10(12) Hz) between these ranges has remained largely underdeveloped, despite the identification of various possible applications--for example, chemical detection, astronomy and medical imaging. Progress in this area has been hampered by the lack of compact, low-consumption, solid-state terahertz sources. Here we report a monolithic terahertz injection laser that is based on interminiband transitions in the conduction band of a semiconductor (GaAs/AlGaAs) heterostructure. The prototype demonstrated emits a single mode at 4.4 THz, and already shows high output powers of more than 2 mW with low threshold current densities of about a few hundred A cm(-2) up to 50 K. These results are very promising for extending the present laser concept to continuous-wave and high-temperature operation, which would lead to implementation in practical photonic systems.

2,132 citations


Journal ArticleDOI
TL;DR: In this paper, a Pentacene-based thin-film integrated circuit with polymeric shadow masks and powered by near-field coupling at radio frequencies of 125 kHz and above 6 MHz has been demonstrated.
Abstract: Pentacene-based thin-film integrated circuits patterned only with polymeric shadow masks and powered by near-field coupling at radio frequencies of 125 kHz and above 6 MHz have been demonstrated. Sufficient amplitude modulation of the rf field was obtained to externally detect a clock signal generated by the integrated circuit. The circuits operate without the use of a diode rectification stage. This demonstration provides the basis for more sophisticated low-cost rf transponder circuitry using organic semiconductors.

753 citations


Journal ArticleDOI
TL;DR: The experimental hole mobilities extracted from both types of devices, although based on a single polymeric semiconductor, can differ by 3 orders of magnitude, demonstrating the strong dependence of the hole mobility on the charge carrier density in disordered semiconducting polymers.
Abstract: A systematic study of the hole mobility in hole-only diodes and field-effect transistors based on poly(2-methoxy-5-(3('),7(')-dimethyloctyloxy)-p-phenylene vinylene) and on amorphous poly(3-hexyl thiophene) has been performed as a function of temperature and applied bias. The experimental hole mobilities extracted from both types of devices, although based on a single polymeric semiconductor, can differ by 3 orders of magnitude. We demonstrate that this apparent discrepancy originates from the strong dependence of the hole mobility on the charge carrier density in disordered semiconducting polymers.

697 citations


Patent
03 Oct 2003
TL;DR: In this article, a light-emitting diode comprising a semiconductor layer 2 which is made of a GaAs compound semiconductor and has a pn junction therein on the upper surface of a single crystal substrate was presented.
Abstract: PROBLEM TO BE SOLVED: To provide a light-emitting diode which improves efficiency in the extraction of light and maintains the small size of its whole structure with high productivity. SOLUTION: The light-emitting diode comprising a semiconductor layer 2 which is made of a GaAs compound semiconductor and has a pn junction therein on the upper surface of a single crystal substrate 1, the light-emitting diode emitting light generated around the pn junction from the upper surface of the semiconductor layer 2, wherein a number of recesses 2a are formed on the upper surface of the semiconductor layer 2 and projections 3 made of an oxide of an GaAs compound semiconductor are caused to adhere to parts not having the recesses 2a on the upper surface of the semiconductor layer 2. COPYRIGHT: (C)2004,JPO

467 citations


Journal ArticleDOI
TL;DR: In this paper, the fabrication of n-ZnO/p-AlGaN heterojunction light-emitting diodes on 6H-SiC substrates is described.
Abstract: We report on the fabrication of n-ZnO/p-AlGaN heterojunction light-emitting diodes on 6H-SiC substrates. Hydride vapor phase epitaxy was used to grow p-type AlGaN, while chemical vapor deposition was used to produce the n-type ZnO layers. Diode-like, rectifying I-V characteristics, with threshold voltage ~3.2V and low reverse leakage current ~10(-7)A, are observed at room temperature. Intense ultraviolet emission with a peak wavelength near 389 mn is observed when the diode is forward biased; this emission is found to be stable at temperatures up to 500K and shown to originate from recombination within the ZnO.

445 citations


Journal ArticleDOI
TL;DR: In this paper, a widebandgap heterojunction light-emitting diodes based on the n-ZnO/p-GaN material system was reported, and room-temperature electroluminescence in the blue-violet region with peak wavelength 430 nm was observed.
Abstract: In this work, we report on the growth, fabrication, and device characterization of wide-band-gap heterojunction light-emitting diodes based on the n-ZnO/p-GaN material system. The layer structure is achieved by first growing a Mg-doped GaN film of thickness 1 μm on Al2O3(0001) by molecular-beam epitaxy, then by growing Ga-doped ZnO film of thickness 1 μm by chemical vapor deposition on the p-GaN layer. Room-temperature electroluminescence in the blue-violet region with peak wavelength 430 nm is observed from this structure under forward bias. Light–current characteristics of these light-emitting diodes are reported, and a superlinear behavior in the low current range with a slope 1.9 and a sublinear behavior with a slope 0.85 in the high current range are observed.

430 citations


Journal ArticleDOI
TL;DR: In this paper, a transparent trilayered oxide films of ZnO/NiO/indium tin oxide were heteroepitaxially grown on a YSZ (111) substrate by pulsed-laser deposition combined with a solid-phaseepitaxy technique.
Abstract: Transparent trilayered oxide films of ZnO/NiO/indium tin oxide were heteroepitaxially grown on a YSZ (111) substrate by pulsed-laser deposition combined with a solid-phase-epitaxy technique, and were processed to fabricate a p-NiO/n-ZnO diode. The diode exhibited a clear rectifying I–V characteristic with an ideality factor of ∼2 and a forward threshold voltage of ∼1 V. Although the photoresponsivity was fairly weak at the zero-bias voltage, it was enhanced up to ∼0.3 A W−1 through the application of a reverse bias of −6 V under the irradiation of 360 nm light, a value comparable to that of commercial devices.

331 citations


Patent
08 May 2003
TL;DR: A high-intensity light source is formed by a micro array of a semiconductor light source such as a LEDs, laser diodes, or VCSEL placed densely on a liquid or gas cooled thermally conductive substrate as mentioned in this paper.
Abstract: A high-intensity light source is formed by a micro array of a semiconductor light source such as a LEDs, laser diodes, or VCSEL placed densely on a liquid or gas cooled thermally conductive substrate. The semiconductor devices are typically attached by a joining process to electrically conductive patterns on the substrate, and driven by a microprocessor controlled power supply. An optic element is placed over the micro array to achieve improved directionality, intensity, and/or spectral purity of the output beam. The light module may be used for such processes as, for example, fluorescence, inspection and measurement, photopolymerzation, ionization, sterilization, debris removal, and other photochemical processes.

299 citations


Journal ArticleDOI
TL;DR: The 2-D diode array is ideal for per-plan quality assurance after an IMRT system is fully commissioned and has linear response when beam fluence changes by over 300-fold, which is typical of the level of modulation in intensity modulated radiation therapy, IMRT, beams.
Abstract: An analysis is made of a two-dimensional array of diodes that can be used for measuring dose generated in a plane by a radiation beam. This measuring device is the MapCHECK Model 1175 (Sun Nuclear, Melbourne, FL). This device has 445 N-type diodes in a 22 x 22 cm2 2-D array with variable spacing. The entire array of diodes is easily calibrated to allow for measurements in absolute dose. For IMRT quality assurance, each beam is measured individually with the beam central axis oriented perpendicular to the plane of diodes. Software is available to do the analytical comparison of measurements versus dose distributions calculated by a treatment planning system. Comparison criteria of percent difference and distance-to-agreement are defined by the operator. Data are presented that show the diode array has linear response when beam fluence changes by over 300-fold, which is typical of the level of modulation in intensity modulated radiation therapy, IMRT, beams. A linear dependence is also shown for a 100-fold change in monitors units delivered. Methods for how this device can be used in the clinic for quality assurance of IMRT fields are described. Measurements of typical IMRT beams that are modulated by compensators and MLCs are presented with comparisons to treatment planning system dose calculations. A time analysis is done for typical IMRT quality assurance measurements. The setup, calibration, and analysis time for the 2-D diode array are on the order of 20 min, depending on numbers of fields. This is significantly less time than required to do similar analysis with radiographic film. The 2-D diode array is ideal for per-plan quality assurance after an IMRT system is fully commissioned.

273 citations


Journal ArticleDOI
TL;DR: In this paper, a single photon detector with a silicon avalanche photodiode and a quenching circuit is presented, which exhibits a dead time as low as 75 ns and a relatively low afterpulsing probability of 7.5% at 5 V excess bias voltage.
Abstract: In this article, a fully integrated single photon detector including a silicon avalanche photodiode and a quenching circuit is presented. The low doping concentrations, inherent to the complementary metal–oxide–semiconductor (CMOS) high-voltage technology used, favor the absorption of red and infrared photons at the depletion region. The detection probability rapidly increases with excess bias voltages up to 5 V. At this value, the detection probability is larger than 20% between 420 nm and 620 nm and still 7% at 750 nm. The photosensitive area is 7 μm in diameter. Cointegration of the diode and the quenching resistor allows a drastic reduction of parasitic capacitances. Though passively quenched, the single photon detector exhibits a dead time as low as 75 ns. The avalanche current is quickly quenched in less than 3.5 ns leading to a relatively low afterpulsing probability of 7.5% at 5 V excess bias voltage. The afterpulses are located in the first microseconds after the avalanche event. At room temperature, the dark count rate is about 900 Hz at 5 V excess bias voltage. Cooling of the sensor below 0 °C is of minor interest since the tunneling process becomes dominant. A remarkably short timing resolution has been obtained with values lower than 50 ps for excess bias voltage higher than 5 V. The industrial CMOS high-voltage technology used guarantees low production costs. In applications where the light can be focused on the small photosensitive area using a high magnification objective, the fabricated single photon avalanche photodiode overcomes the features of standard photomultiplier tubes. The CMOS integration opens the way to the fabrication of an extremely compact array. The design can be easily fitted to a dedicated application. Furthermore, by using an industrial CMOS process, the cointegration of data processing electronics to produce a smart sensor would be a feasible task.

243 citations


Journal ArticleDOI
TL;DR: In this article, a transparent ultraviolet (UV)-detector was fabricated using a high quality pn-heterojunction diode composed of transparent oxide semiconductors, p-type NiO and n-type ZnO, and its UV-response was measured at room temperature.

Patent
05 May 2003
TL;DR: In this article, a light source that utilizes light emitting diodes (109) that emit white light was presented, which is mounted on an elongated member having at least two surfaces upon which the light emitting Diodes are mounted.
Abstract: The present invention relates to a light source that utilizes light emitting diodes (109) that emit white light. The diodes are mounted on an elongated member (101) having at least two surfaces upon which the light emitting diodes are mounted. The elongate member is thermally conductive and is utilized to cool the light emitting diodes. In the illustrative embodiment, the elongate member is a tubular member through which a heat transfer medium flows.

Journal ArticleDOI
TL;DR: In this article, an electrically modulated silicon-on-insulator (SOI) submicrometer-size high-index-contrast waveguide was proposed and analyzed.
Abstract: In this paper, we propose and analyze an electrically modulated silicon-on-insulator (SOI) submicrometer-size high-index-contrast waveguide. The geometry of the waveguide provides high lateral optical confinement and defines a lateral p-i-n diode. The electrooptic structure is electrically and optically modeled. The effect of the waveguide geometry on the device performance is studied. Our calculations indicate that this scheme can be used to implement submicrometer high-index-contrast waveguide active devices on SOI. As an example of application, a one-dimensional microcavity intensity modulator is predicted to exhibit a modulation depth as high as 80% by employing a dc power consumption as low as 14 /spl mu/W.

Journal ArticleDOI
TL;DR: In this paper, the authors used microwave plasma chemical vapour deposition to grow epitaxial diamond layers with low boron doping, from 5 × 1014 to 1 × 1016 cm−3, and the compensating n-type impurities are the lowest reported for any semiconducting diamond, 700 °C for 1 s in air.
Abstract: Exceptionally pure epitaxial diamond layers have been grown by microwave plasma chemical vapour deposition, which have low boron doping, from 5 × 1014 to 1 × 1016 cm−3, and the compensating n-type impurities are the lowest reported for any semiconducting diamond, 700 °C for ~1 s in air. Schottky diodes made on these epitaxial diamond films have breakdown voltages >6 kV, twelve times the highest breakdown voltage reported for any diamond diode and higher than any other semiconductor Schottky diode.

Journal ArticleDOI
TL;DR: In this paper, a two-dimensional array (4 by 8) of single-photon avalanche diodes integrated in an industrial complementary metal-oxide-semiconductor (CMOS) process is presented.
Abstract: A two-dimensional (2-D) array (4 by 8) of single-photon avalanche diodes integrated in an industrial complementary metal-oxide-semiconductor (CMOS) process is presented. Each pixel combines a photodiode biased above its breakdown voltage in the so-called Geiger mode, a quenching resistor, and a simple comparator. The pitch between the pixels is 75 /spl mu/m and the diameter of each pixel is 6.4 /spl mu/m. The full integration allows reducing the number of charge carriers in a Geiger pulse. The electroluminescence responsible for optical crosstalks between pixels is then reduced leading to a negligible optical crosstalk probability. Thanks to the cleanness of the fabrication process, no afterpulsing effects are noticed. At room temperature, most of the pixels exhibit a dark-count rate of about 50 Hz. The detection probability is almost identical for all 32 pixels of the array with relative variation in the range of a few percents. This letter demonstrates the feasibility of an array of single-photon detectors sensitive in the visible part of the spectrum. Besides low production costs and compactness, an undeniable benefit lies in the potential to easily modify the design to fit a specific application. Furthermore, the CMOS integration opens the way to on-chip data processing.

Patent
Christopher Petti, S. Herner1
03 Dec 2003
TL;DR: In this article, a vertically oriented junction diode having a contact-antifuse unit in contact with one of its electrodes is presented. But the junction diodes and contact-ANTIFuse unit can be used as a memory cell, which is advantageously used in a monolithic three dimensional memory array.
Abstract: The invention provides for a vertically oriented junction diode having a contact-antifuse unit in contact with one of its electrodes. The contact-antifuse unit is formed either above or below the junction diode, and comprises a silicide with a dielectric antifuse layer formed on and in contact with it. In preferred embodiments, the silicide is cobalt silicide, and the antifuse is preferably silicon oxide, silicon nitride, or silicon oxynitride grown on the cobalt silicide. The junction diode and contact-antifuse unit can be used as a memory cell, which is advantageously used in a monolithic three dimensional memory array.

Patent
Sei-Hyung Ryu1
24 Apr 2003
TL;DR: The Schottky diode may have an active area less than the active area of a built-in body diode of the DMOSFET as mentioned in this paper, and it may have a turn-on voltage lower than that of the body diodes.
Abstract: Silicon carbide semiconductor devices and methods of fabricating silicon carbide semiconductor devices have a silicon carbide DMOSFET and an integral silicon carbide Schottky diode configured to at least partially bypass a built in diode of the DMOSFET. The Schottky diode may be a junction barrier Schottky diode and may have a turn-on voltage lower than a turn-on voltage of a built-in body diode of the DMOSFET. The Schottky diode may have an active area less than an active area of the DMOSFET.

Journal ArticleDOI
TL;DR: In this article, a pixel circuit using hydrogenated amorphous silicon (a-Si:H) thin-film transistors (TFTs), composed of three switching and one driving TFT, for active-matrix organic light-emitting diodes (AMOLEDs) with a voltage source method was proposed.
Abstract: We propose a new pixel circuit using hydrogenated amorphous silicon (a-Si:H) thin-film transistors (TFTs), composed of three switching and one driving TFT, for active-matrix organic light-emitting diodes (AMOLEDs) with a voltage source method. The circuit simulation results based on the measured threshold voltage shift of a-Si:H TFTs by gate-bias stress indicate that this circuit compensates for the threshold voltage shifts over 10000 h of operation.

Journal ArticleDOI
TL;DR: In this paper, experiments on the production of low-energy, high-current electron beams (LEHCEB) and their use for surface modification of materials have been conducted and it has been shown that if the rise time of the accelerating voltage is comparable to or shorter than the time it takes for an ion to fly through the charge layer, the electric field strength at the cathode and the electron current density in the layer are increased.
Abstract: This article reviews experiments on the production of low-energy, high-current electron beams (LEHCEB) and their use for surface modification of materials. It is shown that electron guns with a plasma anode and an explosive emission cathode are most promising for the production of this type of beams. The problems related to the initiation of explosive emission and the production and transportation of LEHCEBs in plasma-filled diodes are considered. It has been shown that if the rise time of the accelerating voltage is comparable to or shorter than the time it takes for an ion to fly through the space charge layer, the electric field strength at the cathode and the electron current density in the layer are increased. Experimentally, it has been established that the current of the beam transported in the plasma channel is 1–2 orders of magnitude greater than the critical Pierce current and several times greater than the chaotic current of the anode plasma electrons. Methods for improving the uniformity of the energy density distribution over the beam cross section are described. The nonstationary temperature and stress fields formed in metal targets have been calculated. The features of the structure-phase transformations in the surface layers of materials irradiated with LEHCEBs have been considered. It has been demonstrated that in the surface layers quenched from the liquid state, nonequilibrium structure-phase states are formed.

Journal ArticleDOI
TL;DR: In this article, the authors demonstrate a molecular rectifying junction made from a sequential self-assembly on silicon, which consists of only one conjugated (p) group and an alkyl spacer chain.
Abstract: We demonstrate a molecular rectifying junction made from a sequential self-assembly on silicon. The device structure consists of only one conjugated (p) group and an alkyl spacer chain. We obtain rectification ratios up to 37 and threshold voltages for rectification between -0.3V and -0.9V. We show that rectification occurs from resonance through the highest occupied molecular orbital of the p-group in good agreement with our calculations and internal photoemission spectroscopy. This approach allows us to fabricate molecular rectifying diodes compatible with silicon nanotechnologies for future hybrid circuitries.

Journal ArticleDOI
TL;DR: Electrical and optical degradations of GaN/InGaN single-quantum-well light-emitting diodes (LEDs) under high-injection current and reverse-bias stresses were investigated, and the stressed LEDs exhibited minimal degradation of optical characteristics.

Journal ArticleDOI
TL;DR: In this paper, the property of GaInN-AlGaN heterostructures with low internal loss is described and the design of the near active region is optimized to achieve stable continuous operation under 50mW continuous wave at 70/spl deg/C.
Abstract: The property of GaInN-AlGaN heterostructures and GaInN multiple quantum well (MQW) gain GaInN laser diodes with low internal loss are described. GaInN blue-violet laser diodes have been developed as a light source for optical disk recording. However, the threshold current density of these diodes has been difficult to reduce and remains high at around 3-4 kA/cm/sup 2/. This is thought to be due to the large transparency current density Jt and the large optical internal loss /spl alpha//sub i/. Recently, the internal loss was successfully reduced to 13.6 cm/sup -1/ by optimizing the design of the near active region and achieved stable continuous operation under 50-mW continuous wave at 70/spl deg/C. Other laser characteristics such as far-field patterns and laser noise have also been improved for optical disk use.

Journal ArticleDOI
TL;DR: In this article, a planar Fabry-Perot microcavity with deep Si/SiO/sub 2/Bragg reflectors is used to constrain both optical field and charge carriers in a micron-size region.
Abstract: We propose and analyze a novel compact electrooptic modulator on a silicon-on-insulator (SOI) rib waveguide. The device confines both optical field and charge carriers in a micron-size region. The optical field is confined by using a planar Fabry-Perot microcavity with deep Si/SiO/sub 2/ Bragg reflectors. Carriers are laterally confined in the cavity region by employing deep-etched trenches. The refractive index of the cavity is varied by using the free-carrier dispersion effect produced by a p-i-n diode. The device has been designed and analyzed using electrical and optical simulations. Our calculations predict, for a 20-/spl mu/m-long device, a modulation depth of around 80% and a transmittance of 86% at an operating wavelength of 1.55 /spl mu/m by using an electrical power under dc conditions on the order of 25 /spl mu/W.

Book
07 Nov 2003
TL;DR: In this paper, the above threshold analysis and optimization of DFB laser Diodes using the Transfer Matrix Method is presented. But this method is not suitable for the above-threshold analysis of DFTD structures.
Abstract: Preface.Acknowledgements.Glossary of Abbreviations.Glossary of Symbols.1. An Introduction to Optical Communication Systems.2. Principles of Distributed Feedback Semiconductor Laser Diodes: Coupled Wave Theory.3. Structural Impacts on the Solutions of Coupled Wave Equations: An Overview.4. Transfer Matrix Modelling in DFB Semiconductor Lasers.5. Threshold Analysis and Optimization of Various DFB LDs Using the Transfer Matrix Method.6. Above-Threshold Characteristics of DFB Laser Diodes: A TMM Approach.7. Above-Threshold Analysis of Various DFB Lase r Structures Using the TMM.8. Circuit and Transmission-Line Laser Modelling (TLLM) Techniques.9. Analysis of DFB Laser Diode Characteristics Based on the Transmission-Line Modelling (TLLM).10. Wavelength Tunable Optical Filters Based on DFB Laser Structures.11. Other Wavelenght Tunable Optical Filters Based on the DFB Laser Structure.12. Conclusion, Summary and Suggestions.Index.

Journal ArticleDOI
TL;DR: In this paper, the Schottky-Mott model for the energy level alignment in polyfluorene-based light-emitting diodes was used to evaluate the effect of the interfacial interfacial energy level lineup on electron injection.
Abstract: The electronic nature of metal-semiconductor contacts is a fundamental issue in the understanding of semiconductor device physics, because such contacts control charge injection, and therefore play a major role in determining the electron/hole population in the semiconductor itself. This role is particularly important for organic semiconductors as they are generally used in their pristine, undoped form. Here, we review our progress in the understanding of the energy level line-up in finished, blue-emitting, polyfluorene-based light-emitting diodes, which exploit LiF and CsF thin films in combination with Ca and Al to obtain cathodes with low injection barriers. We have used electroabsorption measurements, as they allow the noninvasive determination of the built-in potential when changing the cathode. This provides precious experimental information on the alteration of the polymer/cathode interfacial energy level line-up. The latter is found to depend strongly on the electrode work function. Thus, the Schottky–Mott model for the energy level alignment is found to be a better first-order approximation than those models where strong pinning or large interface dipoles determine the alignment (e.g., Bardeen model), except for electrodes that extensively react with the polymer, and introduce deep gap states. In addition, we show results that validate the approximation of rigid tilting of polymer energy levels with bias (for biases for which no significant injection of carriers occurs). To investigate further the consequences of the electronic line-up on device operation, we complemented the electroabsorption measurements with characterization of the emissive and transport properties of the light-emitting diodes, and confirmed that the cathodic barrier lowering in CsF/Ca/Al and LiF/Ca/Al electrodes leads to the best improvements in electron injection. We found that luminance and overall current are greatly affected by the barrier-reducing cathodes, indicating a truly bipolar transport, with comparable electron and hole currents. We also found significant indications of CsF/Ca/Al cathodes strongly reacting with the polymer, which is suggestive of CsF dissociation and diffusion in the bulk of the polymer.

Journal ArticleDOI
TL;DR: In this article, a transparent p-n junction composed of zinc oxide, copper-aluminum oxide and indium-tin oxide films was fabricated by pulsed laser deposition on glass substrates at temperatures as low as 400 °C.

Journal ArticleDOI
TL;DR: In this paper, the authors demonstrate 4.5 mW output power from AlGaN-based single quantum well ultraviolet light-emitting diodes at a very short wavelength of 267 nm in pulsed operation mode.
Abstract: We demonstrate 4.5 mW output power from AlGaN-based single quantum well ultraviolet light-emitting diodes at a very short wavelength of 267 nm in pulsed operation mode. The output power in continuous-wave mode reaches a value of 165 μW at an injected current of 435 mA. The measurements were done on arrays of four devices flip chip bonded to AlN submounts for thermal management.

Patent
14 Mar 2003
TL;DR: New organic light-emitting diodes and related electroluminescent devices and methods for fabrication, using siloxane self-assembly techniques are described in this article.
Abstract: New organic light-emitting diodes and related electroluminescent devices and methods for fabrication, using siloxane self-assembly techniques.

Patent
10 Oct 2003
TL;DR: In this paper, the authors proposed a method to transfer a light-emitting device having an organic compound to a substrate with high thermal conductivity, such as a TFT, to prevent deterioration due to penetration of moisture or oxygen.
Abstract: It is an object of the present invention to provide a semiconductor device capable of preventing deterioration due to penetration of moisture or oxygen, for example, a light-emitting apparatus having an organic light-emitting device that is formed over a plastic substrate, and a liquid crystal display apparatus using a plastic substrate. According to the present invention, devices formed on a glass substrate or a quartz substrate (a TFT, a light-emitting device having an organic compound, a liquid crystal device, a memory device, a thin-film diode, a pin-junction silicon photoelectric converter, a silicon resistance element, or the like) are separated from the substrate, and transferred to a plastic substrate having high thermal conductivity.

Journal ArticleDOI
TL;DR: In this article, the authors investigated the possible mechanisms responsible for the improvement in performance of micro-light emitting diode (LED) arrays with diameters of 4 to 20 mum and were found to be much more efficient light emitters compared to their broad area counterparts, with up to five times enhancement in optical power densities.
Abstract: Micro-light emitting diode (LED) arrays with diameters of 4 to 20 mum have been fabricated and were found to be much more efficient light emitters compared to their broad-area counterparts, with up to five times enhancement in optical power densities. The possible mechanisms responsible for the improvement in performance were investigated. Strain relaxation in the microstructures as measured by Raman spectroscopy was not observed, arguing against theories of an increase in internal quantum efficiency due to a reduction of the piezoelectric field put forward by other groups. Optical microscope images show intense light emission at the periphery of the devices, as a result of light scattering off the etched sidewalls. This increases the extraction efficiency relative to broad area devices and boosts the forward optical output. In addition, spectra of the forward emitted light reveal the presence of resonant cavity modes [whispering gallery (WG) modes in particular] which appear to play a role in enhancing the optical output.