Hao-Chung Kuo

Hao-Chung Kuo
National Chiao Tung University | NCTU · Department of Photonics

Ph.D. UIUC

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1,252
Publications
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Introduction
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Publications

Publications (1,252)
Article
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In this work, a vertical gallium nitride (GaN)-based trench MOSFET on 4-inch free-standing GaN substrate is presented with threshold voltage of 3.15 V, specific on-resistance of 1.93 mΩ·cm ² , breakdown voltage of 1306 V, and figure of merit of 0.88 GW/cm ² . High-quality and stable MOS interface is obtained through two-step process, including simp...
Article
Full-text available
With the increasing demand of silicon carbide (SiC) power devices that outperform the silicon-based devices, high cost and low yield of SiC manufacturing process are the most urgent issues yet to be solved. It has been shown that the performance of SiC devices is largely influenced by the presence of so-called killer defects, formed during the proc...
Article
Full-text available
Internet of Things (IoT) technology is prosperous for the betterment of human well-being. With the expeditious needs of miniature functional devices and systems for adaptive optics and light manipulation at will, relevant sensing techniques are thus in the urgent stage of development. Extensive developments in ultrathin artificial structures, namel...
Article
In order to investigate the photoelectric characteristics of 80×120 µm2 Mini-LEDs with sidewall passivation by atomic layer deposition (ALD), this paper uses the techniques of spectrometer-based spectroradiometer and microscopic hyperspectral imaging. The temperature-dependent electroluminescence (TDEL) is measured using a spectrometer-based spectr...
Article
Nowadays, the flurry of autonomous vehicles is in full swing regarding light detection and ranging (LiDAR) and depth perception. For such visual perception, light plays an important role. We human beings recognize and distinguish surrounding details when the eye focuses light on the retina. For the LiDAR system, pulsed lasers are employed to measur...
Article
Full-text available
In this study, we investigated the characteristic difference between the two different configurations of the three-dimensional shell–core nanorod LED. We achieve a degree of polarization of 0.545 for tip-free core–shell nanorod LED and 0.188 for tip core–shell nanorod LED by combining the three-dimensional (3D) structure LED with photonic crystal....
Article
Full-text available
Fine-pitch backlight technology is rapidly evolving along with display technology, and chips are increasingly designed for direct integration with modules. This study used a distributed Bragg reflector (DBR) for mini light-emitting diode (mini-LED) backlights with high dynamic contrast and developed a digital twin design by using a light-emitting d...
Article
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The solar cell has a poor spectral response in the UV region, which affects its power conversion efficiency (PCE). The utilization of a luminescent downshifting (LDS) layer has been suggested to improve the spectral response of the photovoltaics in the short wavelength region through photoluminescence (PL) conversion and antireflection effects, whi...
Article
Tin doped indium oxide (ITO) film was prepared by high power impulse magnetron sputtering. The effects of power density on the compositional and structural evolution of the film were investigated. The higher power density was found to increase the Sn/In ratio due to the weakening of self-sputtering effect as the initial energy of sputtered species...
Article
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Owing to the superior properties of silicon carbide (SiC), such as higher breakdown voltage, higher thermal conductivity, higher operating frequency, higher operating temperature, and higher saturation drift velocity, SiC has attracted much attention from researchers and the industry for decades. With the advances in material science and processing...
Article
Si-doped Ga2O3 films were prepared on quartz and silicon substrates using remote plasma atomic layer deposition with trimethylgallium, Bis(diethylamino)silane and O2 plasma as the precursors. Different Si doped concentration in films were obtained by adjusting the numbers of SiO2 circulation ratio. The effect of Si-doped concentration from 0 to 20%...
Article
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Two-dimensional materials, such as transition metal dichalogenides (TMDs), are emerging materials for optoelectronic applications due to their exceptional light–matter interaction characteristics. At room temperature, the coupling of excitons in monolayer TMDs with light opens up promising possibilities for realistic electronics. Controlling light–...
Article
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Under pulsed modulation, the emission uniformity in terms of pulsewidth and delay of a 940 nm multimode vertical‐cavity surface‐emitting laser (MM‐VCSEL) array is characterized by analyzing the position‐dependent pulsating and chirping dynamics among localized 600 VCSEL elements. In addition, the MM‐VCSEL array biased nearly threshold current (Ith)...
Article
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Micro-light-emitting diodes (Micro-LEDs) based on gallium nitride (GaN) materials offer versatile platforms for various applications, including displays, data communication tools, photodetectors, and sensors. In particular, the introduction of Micro-LEDs in the optoelectronic industry enables the development of novel short-distance wireless communi...
Article
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This study fabricated and analyzed AlGaInP-based red microlight-emitting diodes (LEDs) ranging from 2 to 15 m in size. To collect photons from a single micro-LED at this scale, a solar cell chip near the micro-LEDs was used. Quantum efficiency decreased at a faster rate than that predicted by the standard ABC model under high currents, and a leakag...
Article
This study demonstrates a Zn-diffusion few-mode (FM) vertical-cavity surface-emitting laser (VCSEL) with a performance of the quasi-single-mode, SMSR over 20 dB. The VCSELs have a stable output power due to the larger oxide aperture because high-order transverse modes are suppressed through impurity-induced disordering of Zn-diffusion. The VCSEL ha...
Article
Full-text available
As a representative wide bandgap semiconductor material, gallium nitride (GaN) has attracted increasing attention because of its superior material properties (e.g., high electron mobility, high electron saturation velocity, and critical electric field). Vertical GaN devices have been investigated, are regarded as one of the most promising candidate...
Article
Full-text available
In this study, we demonstrated large-area high-quality multi-color emission from the 12-fold symmetric GaN photonic quasicrystal nanorod device which was fabricated using the nanoimprint lithography technology and multiple quantum wells regrowth procedure. High-efficiency blue and green color emission wavelengths of 460 and 520 nm from the regrown...
Article
Full-text available
In recent years, the process requirements of nano-devices have led to the gradual reduction in the scale of semiconductor devices, and the consequent non-negligible sidewall defects caused by etching. Since plasma-enhanced chemical vapor deposition can no longer provide sufficient step coverage, the characteristics of atomic layer deposition ALD te...
Article
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Coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has emerged as a serious threat to human health worldwide. The inactivation of SARS-CoV-2 on object surfaces and in the indoor air might help to halt the COVID-19 pandemic. Far-ultraviolet light (UVC) disinfection has been proven to be highly...
Article
In this study, deep ultraviolet light-emitting diodes (DUV-LEDs) with a reflective passivation layer (RPL) were investigated. The RPL consists of HfO2/SiO2 stacks as distributed Bragg reflectors, which are deposited on two DUV-LEDs with different p-GaN thicknesses. The RPL structure improved the external quantum efficiency droops of the DUV-LEDs wi...
Article
Full-text available
In this paper, we demonstrate the design and fabrication of a high-power, high-speed flip-chip vertical cavity surface emitting laser (VCSEL) for light detection and ranging (LiDAR) systems. The optoelectronic characteristics and modulation speeds of vertical and flip-chip VCSELs were investigated numerically and experimentally. The thermal transpo...
Article
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Quantum dot (QD)-based RGB micro-LED technology is seen as one of the most promising approaches towards full color micro-LED displays. In this work, we present a novel nanoporous GaN (NP-GaN) structure that can scatter light and host QDs, as well as a new type of micro-LED array based on an NP-GaN embedded with QDs. Compared to typical QD films, th...
Article
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This work combines the high-temperature sintering method and atomic layer deposition (ALD) technique, and yields SiO2 /AlOx -sealed γ-CsPbI3 nanocrystals (NCs). The black-phase CsPbI3 NCs, scattered and encapsulated firmly in solid SiO2 sub-micron particles, maintain in black phases against water soaking, ultraviolet irradiation, and heating, exhib...
Article
We propose a flexible white-light system for high-speed visible-light communication (VLC) applications, which consists of a semipolar blue InGaN/GaN single-quantum-well micro-light-emitting diode (LED) on a flexible substrate pumping green CsPbBr3 perovskite quantum-dot (PQD) paper in nanostructure form and red CdSe QD paper. The highest bandwidth...
Article
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GaN HEMT has attracted a lot of attention in recent years owing to its wide applications from the high-frequency power amplifier to the high voltage devices used in power electronic systems. Development of GaN HEMT on Si-based substrate is currently the main focus of the industry to reduce the cost as well as to integrate GaN with Si-based componen...
Article
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Visible light communication (VLC) is an advanced, highly developed optical wireless communication (OWC) technology that can simultaneously provide lighting and high-speed wireless data transmission. A VLC system has several key advantages: ultra-high data rate, secure communication channels, and a lack of interference from electromagnetic (EM) wave...
Article
We propose and demonstrate a green semipolar (20-21) micro-light emitting diode (LED) acting as a high speed visible light communication (VLC) photodiode (PD). The micro-LED PD has the optical-to-electrical (OE) response of 228 MHz. A record data rate of 540 Mbit/s in on-off-keying (OOK) format with free-space transmission distance of 1.1 m was ach...
Article
Full-text available
Many automated optical inspection (AOI) companies use supervised object detection networks to inspect items, a technique which expends tremendous time and energy to mark defectives. Therefore, we propose an AOI system which uses an unsupervised learning network as the base algorithm to simultaneously generate anomaly alerts and reduce labeling cost...
Article
A green 2 × 2 micro light-emitting diode (μ-LED) array with nanostructured grating patterns grown on a semipolar (20-21)-oriented gallium nitride (GaN) buffered layer on (22-43)-oriented sapphire substrate is specially transistor-outline can (TO-can) packaged with a sub-miniature-A (SMA) connector for high-speed data communication beyond 5 Gbit/s....
Article
Micro‐LEDs (μ‐LEDs) are well known to have a thriving future in the next‐generation display field. However, conventional μ‐LEDs grown on c‐plane GaN have a severe wavelength shift due to the quantum confined Stark effect (QCSE), which seriously affects the color quality of μ‐LEDs display. In order to fundamentally solve this problem, we grown blue...
Article
The role of a superlattice distributed Bragg reflector (SL DBR) as the p-type electron blocking layer (EBL) in a GaN micro-light-emitting diode (micro-LED) is numerically investigated to improve wall-plug efficiency (WPE). The DBR consists of AlGaN/GaN superlattice (high refractive index layer) and GaN (low refractive index layer). It is observed t...
Article
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A record 4.343 Gbit/s green color micro-light-emitting-diode (-LED) based visible-light-communication (VLC) is demonstrated. We designed and fabricated the InGaN/GaN -LED array with modulation bandwidth > 1.1 GHz. The micro-LED was grown on semipolar (20-21) orientation, which could offer higher modulation bandwidth at a lower current density.
Article
Full-text available
GaN has been widely used to develop devices for high-power and high-frequency applications owing to its higher breakdown voltage and high electron saturation velocity. The GaN HEMT radio frequency (RF) power amplifier is the first commercialized product which is fabricated using the conventional Au-based III–V device manufacturing process. In recen...
Article
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Two-dimensional quantum dots have received a lot of attention in recent years due to their fascinating properties and widespread applications in sensors, batteries, white light-emitting diodes, photodetectors, phototransistors, etc. Atomically thin two-dimensional quantum dots derived from graphene, layered transition metal dichalcogenide, and phos...
Article
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High-quality epitaxial layers are directly related to internal quantum efficiency. The methods used to design such epitaxial layers are reviewed in this article. The ultraviolet C (UVC) light-emitting diode (LED) epitaxial layer structure exhibits electron leakage; therefore, many research groups have proposed the design of blocking layers and carr...
Article
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We fabricated tantalum pentoxide (Ta2O5) channel waveguides and used them to experimentally demonstrate higher-order mode supercontinuum (SC) generation. The Ta2O5 waveguide has a high nonlinear refractive index which was in an order magnitude of 10–14 cm2/W and was designed to be anomalously dispersive at the pumping wavelength. To the best of our...
Article
MICRO-LEDs ( n-LEDs) HAVE been engaged in the next-generation display technology and evolved for various applications from several electronics manufacturers and institutions. The area of n-LEDs (less than 10 # 10 nm2) is desired for the high pixelsper-inch (PPI) value of the microdisplay, but the sidewall effect from the etching process will drop t...
Article
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In this study, we demonstrate a new design of white light-emitting diode (WLED) with high stability and luminous efficiency as well as positive aging. Colloidal ternary Zn0.8Cd0.2S (named Zn0.8) white quantum dots (WQDs) were prepared by chemical route and dispersed in xylene, integrating them into an ultraviolet light-emitting diode (UV-LED) to fo...
Article
With regard to micro-light-emitting diodes (micro-LEDs), their excellent brightness, low energy consumption, and ultra-high resolution are significant advantages. However, the large size of traditional inorganic phosphors and the number of side defects have restricted the practical applications of small sized micro-LEDs. Recently, quantum dot (QD)...
Article
In this work, we propose adopting step-type quantum wells to improve the external quantum efficiency for GaN-based yellow micro light-emitting diodes. The step-type quantum well is separated into two parts with slightly different InN compositions. The proposed quantum well structure can partially reduce the polarization mismatch between quantum bar...
Preprint
Full-text available
In this study, we demonstrated large-area high quality multi-color emission from the 12-fold symmetric GaN photonic quasicrystal nanorod device which was fabricated using the nanoimprint lithography technology and multiple quantum wells regrowth procedure. High-efficiency blue and green color emission wavelengths of 460 and 520 nm from the regrown...
Article
The external bandwidth of germanium waveguide photodetectors (PDs) decreases with the device length due to the load and parasitic effects even if the internal one is less affected. Shortening PDs raises the external bandwidth but lowers the responsivity, introducing a trade-off between the two figures of merits. Here, we present a scheme of wavegui...
Article
Light‐emitting diodes (LEDs) are a promising solution for energy‐saving illumination, terminal display technology, and visible light communication. Driven by the vast markets of these emergent applications, the everlasting demand for LED devices is to continuously improve the luminous efficiency and lifetime while minimizing costs. The luminous eff...
Chapter
Quantum dots (QDs) are used in displays as they have several advantages including high illumination efficiency and color rendering, low cost, and mass production capacity. The excellent luminescence and transport charging properties of QDs have resulted in their use in QD-based light emitting diodes (LEDs), which have gained significant interest in...