Photon management of GaN-based optoelectronic devices via nanoscaled phenomena

Tsai, Yu Lin; Lai, K. Robert; Lee, Ming Jui; Liao, Yu Kuang; Ooi, Boon S.; Kuo, Hao Chung; He, Jr Hau

doi:10.1016/j.pquantelec.2016.08.001

Cited by 31 publications

(18 citation statements)

References 127 publications

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“…Binary semiconductors, such as InN, AlN, GaAs, InAs, InP, GaN, AlSb, etc., and their alloys, cover an extended range of structures useful in high-end device technology [1,2]. Due to the direct bandgap that most of these materials possess, efficient emission and absorption of light is allowed.…”

Section: Introductionmentioning

confidence: 99%

“…GaN-based devices still encounter several obstructing issues, including high defect density and strain-induced polarization. In order to reduce the effects of these issues, a series of approaches were proposed in the last decade [1]. In the early stages, the main efforts were focused on improving both the qualities of the materials and the structuring of the device.…”

Section: Introductionmentioning

confidence: 99%

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Defect Structure Determination of GaN Films in GaN/AlN/Si Heterostructures by HR-TEM, XRD, and Slow Positrons Experiments

et al. 2020

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The present article evaluates, in qualitative and quantitative manners, the characteristics (i.e., thickness of layers, crystal structures, growth orientation, elemental diffusion depths, edge, and screw dislocation densities), within two GaN/AlN/Si heterostructures, that alter their efficiencies as positron moderators. The structure of the GaN film, AlN buffer layer, substrate, and their growth relationships were determined through high-resolution transmission electron microscopy (HR-TEM). Data resulting from high-resolution X-ray diffraction (HR-XRD) was mathematically modeled to extract dislocation densities and correlation lengths in the GaN film. Positron depth profiling was evaluated through an experimental Doppler broadening spectroscopy (DBS) study, in order to quantify the effective positron diffusion length. The differences in values for both edge ( ρ d e ) and screw ( ρ d s ) dislocation densities, and correlation lengths (Le, Ls) found in the 690 nm GaN film, were associated with the better effective positron diffusion length (Leff) of L eff GaN 2 = 43 ± 6 nm.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Defect Structure Determination of GaN Films in GaN/AlN/Si Heterostructures by HR-TEM, XRD, and Slow Positrons Experiments

et al. 2020

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“…In addition, according to what I have learnt, all reported design principles related to ODR are based on flip-chip LED on flat sapphire substrate (FSS). But nowadays, patterned sapphire substrate (PSS) has been employed in the commercial high-brightness LEDs because it can improve light extraction efficiency [20]- [22] and epitaxial crystal quality [2], [23]. So it is also worth to investigate if the quarter-wave thick low-index dielectric layer in ODR is optimum for flip-chip LED on PSS.…”

Section: Introductionmentioning

confidence: 99%

The Effect of Sapphire Substrates on Omni-Directional Reflector Design for Flip-Chip Near-Ultraviolet Light-Emitting Diodes

Zhang

Zheng

et al. 2019

IEEE Photonics J.

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In this paper, we investigate the effect of omni-directional reflectors (ODRs) on the light extraction efficiency (LEE) for flip-chip near-ultraviolet light-emitting diodes (LEDs) on patterned (PSS) and flat sapphire substrate (FSS) using three-dimensional finite-difference time-domain method. Different design principles of ODR for the flip-chip LEDs on PSS and FSS are proposed to attain optimum LEE. For the flip-chip LED on FSS, the LEE curve is oscillatory with changing the thickness of the SiO 2 layer as a result of the coherent interference in the ODR and the optical cavity tuning effect for light source. Therefore, the thickness of the p-GaN needs to satisfy even times of quarter wave and the thickness of SiO 2 needs to be quarter wave. However, for the flip-chip LED on PSS, both the total internal reflection and the surface plasmon polariton resonance absorption play a major role leading to LEE increasing as the thickness of SiO 2 layer increases. As a result, SiO 2 layer with a thickness of over one wavelength is better, because the energy of evanescent wave decays to sufficiently negligible when it reaches the Al metal.

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“…However, significant challenges are still encountered when these QDs are used in LEDs. Similar to other phosphor materials, such as yttrium aluminitum garnet (YAG) and nitride phosphor, it is necessary to disperse the QDs into a transparent matrix in order to achieve high light extraction [ 7 ] and to simultaneously prevent oxidation [ 8 ]. QDs are easy to aggregate in a matrix due to their small particle size of several nanometers.…”

Section: Introductionmentioning

confidence: 99%

Improvement in Color-Conversion Efficiency and Stability for Quantum-Dot-Based Light-Emitting Diodes Using a Blue Anti-Transmission Film

Tang

Ding

et al. 2018

Nanomaterials

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In this report, a blue anti-transmission film (BATF) has been introduced to improve the color-conversion efficiency (CCE) and the stability of quantum dot (QD) films. The results indicate that the CCE can be increased by as much as 93% using 15 layers of BATFs under the same QD concentration. Therefore, the same CCE can be achieved using BATF-QD hybrid films with a lower QD concentration when compared with standard QD films. The hybrid and QD films with the same CCE of 60% were aged at an environmental temperature of 25°C and with a 10 mA injection current light-emitting diode source. The CCE and luminous efficacy that are gained by the hybrid film increased by 42.8% and 24.5%, respectively, when compared with that gained by the QD film after aging for the same time period of approximately 65 h. In addition, the hybrid film can effectively suppress the red-shift phenomenon of the QD light spectra, as well as an expansion of the full-width at half maximum. Consequently, these BATF-QD hybrid films with excellent optical performance and stability show great potential for illumination and display applications.

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Photon management of GaN-based optoelectronic devices via nanoscaled phenomena

Cited by 31 publications

References 127 publications

Defect Structure Determination of GaN Films in GaN/AlN/Si Heterostructures by HR-TEM, XRD, and Slow Positrons Experiments

Defect Structure Determination of GaN Films in GaN/AlN/Si Heterostructures by HR-TEM, XRD, and Slow Positrons Experiments

The Effect of Sapphire Substrates on Omni-Directional Reflector Design for Flip-Chip Near-Ultraviolet Light-Emitting Diodes

Improvement in Color-Conversion Efficiency and Stability for Quantum-Dot-Based Light-Emitting Diodes Using a Blue Anti-Transmission Film

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