Browsing by Author "Huang, Shen-Che"

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Antibacterial capability of ZnO-based nanostructures manipulated by flake-coated onto silver wires
(2016)
Huang, Shen-Che
;
Wang, Tze-Ting
;
Lu, Tien-Chang
;
Chen, Hsiang
;
光電工程學系
ZnO nanoscale structures were grown on the silver wire, utilizing the electro-hydrothermal method, which deposited to further grow flake-form with pellicle and floccule status via employing certain characterizations. The analysis reveals that ZnO nanoscale flake-form were successfully coated on Ag wire. Besides, the antibacterial testing of sample with ZnO nanoscale flake-form integrated on the polished silver wire may support future detection platforms.
Characterization of spatial manipulation on ZnO nanocomposites consisting of Au nanoparticles, a graphene layer, and ZnO nanorods
(2018-01-01)
Huang, Shen-Che
;
Lu, Chien-Cheng
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Su, Wei-Ming
;
Weng, Chen-Yuan
;
Chen, Yi-Cian
Three types of ZnO-based nanocomposites were fabricated consisting of 80-nm Au nanoparticles (NPs), a graphene layer, and ZnO nanorods (NRs). To investigate interactions between the ZnO NRs and Au nanoparticle, multiple material analysis techniques including field-emission scanning electron microscopy (FESEM), surface contact angle measurements, secondary ion mass spectrometry (SIMS), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopic characterizations were performed. Results indicate that incorporating a graphene layer could block the interaction between the ZnO NRs and the Au NPs. Furthermore, the Raman signal of the Au NPs could be enhanced by inserting a graphene layer on top of the ZnO NRs. Investigation of these graphene-incorporated nanocomposites would be helpful to future studies of the physical properties and Raman analysis of the ZnO-based nanostructure design.
Degradation mechanisms of bias stress on nitride-based near-ultraviolet light-emitting diodes in salt water vapor ambient
(2019-10-15)
Chen, Lih-Ren
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Huang, Shen-Che
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Chiu, Jo-Lun
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Lu, Chien-Cheng
;
Su, Wei-Ming
Degradation mechanisms of nitride-based near-ultraviolet (near-UV) light-emitting diodes (LEDs) were systematically analyzed by applying forward- and reverse-bias stresses to them in a salt water vapor ambient. The surface temperature of the forward-bias stress sample was higher than that of the reverse-bias stress sample. The high temperature of the forward-bias stress sample accelerated the chemical reaction of the device structure with salt water vapors and led to faster degradation. Composition analyses of the sample surface and cross-section were conducted to investigate the failure mechanism. The analyses results indicated that the erosion of the indium-tin-oxide layer enhanced the diffusion of the conducting metal into the LED crystal. The proposed method can effectively characterize the quality of near-UV LEDs in a short duration.
Design of photonic crystal surface emitting lasers with indium-tin-oxide top claddings
(2018-02-05)
Huang, Shen-Che
;
Hong, Kuo-Bin
;
Chiu, Han-Lun
;
Lan, Shao-Wun
;
Chang, Tsu-Chi
Electrically pumped GaAs-based photonic crystal surface emitting lasers were fabricated using a simple fabrication process by directly capping the indium-tin-oxide transparent conducting thin film as the top cladding layer upon a photonic crystal layer. Optimization of the separate-confinement heterostructures of a laser structure is crucial to improving characteristics by providing advantageous optical confinements. The turn-on voltage, series resistance, threshold current, and slope efficiency of the laser with a 100 x 100 mu m(2) photonic crystal area operated at room temperature were 1.3V, 1.5 Omega, 121mA, and 0.2W/A, respectively. Furthermore, we demonstrated a single-lobed lasing wavelength of 928.6 nm at 200mA and a wavelength redshift rate of 0.05 nm/K in temperature-dependent measurements. The device exhibited the maximum output power of approximately 400 mW at an injection current of 2 A; moreover, divergence angles of less than 1 degrees for the unpolarized circular-shaped laser beam were measured at various injection currents. Overall, the low threshold current, excellent beam quality, small divergence, high output power, and high-operating-temperature (up to 343K) of our devices indicate that they can potentially fill the requirements for next-generation light sources and optoelectronic devices. Published by AIP Publishing.
Design, optimization and fabrication of two-dimension high contrast subwavelength grating (HCG) mirror on Silicon-on-insulator
(2015)
Huang, Shen-Che
;
Huang, Qiangsheng
;
Ma, Keqi
;
Zhang, Jianhao
;
Shi, Yaocheng
The high contrast grating (HCG) mirror has been illustrated and characterized. The investigated parameters including grating periods and filling factors were calculated by finite-difference time-domain method. The two-dimension HCG was fabricated by electron-beam lithography and inductively coupled plasma process. The reflectivity of the fabricated HCG mirror was measured, resulting in around 200 nm bandwidth. The measured result also showed a good agreement with calculated one. This achievement was promising in developing the novel light emitters in the telecommunication region.
Effect of passivation layers on characteristics of AlGaInP ridge waveguide laser diodes
(2014-07-01)
Hung, Chih-Tsang
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Huang, Shen-Che
;
Lu, Tien-Chang
;
光電工程學系
;
Department of Photonics
We investigate the effect of passivation structure on the optical mode distribution and characteristics of the edge emitting ridge waveguide AlGaInP-GaInP visible laser diodes (LDs). For conventional designs of single-layer Si3N4 or SiO2 passivation, the variation of lateral near-field confinement and the horizontal far-field (FF) divergence can be determined via the modification of dielectric layer thickness. Thin passivation layer suffers from high absorption at the metal interface while thick passivation layer suffers from poor heat dissipation in the ridge waveguide and high scattering loss, resulting in high threshold. We propose a novel design of three-pair Al2O3/Ta2O5 multilayer optical thin films as passivation on the ridge waveguide, which can improve the laser characteristics and the heat dissipation. The measured room-temperature threshold current (Ith) and characteristic temperature (T-0) are 44.5 mA and 104.2 K with a divergence angle of 16.4. (C) 2013 Elsevier Ltd. All rights reserved.
Electrically driven GaAs-based photonic crystal lasers with ITO cladding layers
(2018-01-01)
Huang, Shen-Che
;
Hong, Kuo-Bin
;
Chiu, Han-Lun
;
Lan, Shao-Wun
;
Lu, Tien-Chang
Photonic crystal (PhC) laser, with specific merits of low astigmatism, single mode operation and integration into silicon photonic system, has been studied for many years. Compared with the edge emitting lasers (EELs), surface emitting light emitters have many advantages such as small and symmetric divergence angle and platform of array-based capability. The resonance along in-plane direction preserves the high modal gain to overcome optical loss and leads to lasing action. These photonic crystal designs which has superior essential performance to that of next-generation light sources which can propose to tunable lasing multi-wavelengths with polarization control and single-mode high beam-quality. In this report, we demonstrate the fabricated realization of a novel electrically driven high-power PhC laser incorporating indium-tin-oxide (ITO) layer as a newly designed cladding layer, which could improve the laser characteristics and achieve the much lower cost of the integrated optoelectronic application. The series of investigated actual nano fabrication lasing devices with distinct designs were observed to verify the structural parameters including grating periods and area regions by tailoring the photonic crystal structure. Based upon experimental results, lasing characteristics through high current injection at room temperature inclusive of I-V curves, L-I curves, near/far field patterns, and lasing spectra were characterized and discussed. We believe this practical watt-level light output achievement should have an impact on numerous photonic devices of the coherent operations and helpful attribution to the two-dimension integrated platform in the future.
Metallic subwavelength grating on GaN-based edge emitting lasers
(2015)
Huang, Shen-Che
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Hong, Kuo-Bin
;
Li, Heng
;
Lu, Tien-Chang
;
光電工程學系
Metallic subwavelength gratings as limit-element linear array can provide the great improving output performance of optical light emitter. We investigated that the device with metallic subwavelength grating can be used to modulate the beam of edge-emitting laser with a patterned facet. Utilizing GaN-based semiconductor laser as a model system, the defined metallic subwavelength slits and gratings is a type of superior reduction method of beam divergence and coupling into other optical components effectively. We believe this study will be helpful for development of the novel light emitting devices in the blue or UV region.
Numerical analysis on current and optical confinement of III-nitride vertical-cavity surface-emitting lasers
(2014-04-21)
Lai, Ying-Yu
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Huang, Shen-Che
;
Ho, Tsung-Lin
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Lu, Tien-Chang
;
Wang, Shing-Chung
We report on the numerical analysis of the electrical and optical properties of current-injected III-nitride based vertical-cavity surface-emitting lasers (VCSELs) with three types of current confinement schemes: the conventional planar-indium tin oxide (ITO) type, the AlN-buried type without ITO, and the hybrid type. The proposed hybrid structure, which combines an ITO layer and an intracavity AlN aperture, exhibits not only uniform current distribution but also enhanced lateral optical confinement. Thus, the hybrid type design shows remarkably better performance including lower threshold current and series resistance compared with the planar-ITO type and the AlN-buried type. Furthermore, the multi-transverse mode lasing behavior induced by strong index guiding of the AlN aperture is suppressed to single transverse mode operation by reducing the aperture size. Such design provides a powerful solution for the high performance III-N based VCSELs and is also viable by using current state of the art processing techniques. (C) 2014 Optical Society of America
Numerical Analysis on Current and Optical Confinement of III-Nitride Vertical-Cavity Surface-Emitting Lasers
(2014)
Lai, Ying-Yu
;
Lu, Tien-Chang
;
Ho, Tsung-Lin
;
Huang, Shen-Che
;
Wang, Shing-Chung
We report on the numerical analysis of the electrical and optical properties of current-injected III-N based vertical-cavity surface-emitting lasers (VCSELs) with three types of current confinement schemes: the conventional planar-Indium Tin Oxide (ITO) type, the AlN-buried type without ITO, and the hybrid type. The proposed hybrid structure, which combines an ITO layer and an intracavity AlN aperture, exhibits not only a uniform current distribution but also an enhanced lateral optical confinement. Thus, the hybrid type design shows a remarkably better performance including lower threshold current and series resistance compared with the planar-ITO type and the AlN-buried type. Furthermore, the multi-transverse mode lasing behavior induced by strong index guiding of the AlN aperture is suppressed to single transverse mode operation by reducing the aperture size. Such design provides a powerful solution for the high performance III-N based VCSELs and is also viable by using current state of the art processing techniques.
Optical Mode Modulation of AlGaInP Multi Quantum Well Laser Diodes
(2013)
Hung, Chih-Tsang
;
Huang, Shen-Che
;
Lu, Tien-Chang
;
光電工程學系
;
Department of Photonics
We investigate the influence of passivation structure on the optical mode distribution and LI characteristics for the edge emitting AlGaInP-GaInP visible laser diode (LD). For traditional single-layer Si3N4 or SiO2 passivation designs, the modification of dielectric layer thickness can determinate the lateral near-field confinement and change the horizontal far-field (FF) divergence. By increasing the film thickness, the non-radiation absorption come from Au-Ti can be improved and it leads to a narrow FF divergence beam. As continue to increasing the thickness, thicker passivation provides a better confinement factor and then the far-field pattern turn to be wider. For LI characteristics, it is necessary to deposit a thick enough passivation to reduce metal absorption. However, it cause much thermal energy accumulated in the ridge waveguide and deteriorate the quantum efficiency as adopting a too thick dielectric layer. Finally, we demonstrate a high power AlGaInP-GaInP multi quantum wells (MQWs) LD adopted a high-reflectivity passivation to enhance the LI characteristics and keep a suitable far-field divergence angle simultaneously. Under the design of three-pair optical thin films, it cannot only avoid the metal absorption but also enhance emitting efficiency and heat dissipation by using a high reflective and good thermal conductive three-pair optical thin films, it cannot only avoid the metal absorption but also enhance emitting efficiency and heat dissipation by using a high reflective and good thermal conductive Al2O3/Ta2O5 multilayer. The measured room-temperature threshold current (I-th) and characteristic temperature (T-0) can be arrived 44.5mA and 104.2K at 16.4 degrees far-fielddivergence.
Photonic crystal surface emitting lasers with novel transparent cladding layers
(2018-01-01)
Huang, Shen-Che
;
Hong, Kuo-Bin
;
Chiu, Han-Lun
;
Lu, Tien-Chang
;
光電工程學系
We reported on novel structures of GaAs-based two-dimensional photonic crystal lasers by capping the ITO transparent conducting thin film as a p-type cladding layer, and measure how greatly serving as excellent performances on high-quality operation at room temperatures.
Reliability Analysis of GaN-based UVLEDs under forward bias operations in salty vapor environment
(2017-01-01)
Huang, Shen-Che
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Li, Heng
;
Lee, Yu-Shan
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Hung, Chen-Hao
;
Wang, Shing-Chung
We illustrated the reliability of longer wavelength ultraviolet light-emitting diodes (UVLEDs) in salty vapour environment under manipulation of forward-bias stress via consistent electrical and material characterizations. By manipulating the unprecedented operation in salty vapour ambient, we investigated a series of remarkable findings related to origin of failure behaviours.
Superior characteristics of microscale light emitting diodes through tightly lateral oxide-confined scheme
(2017-01-09)
Huang, Shen-Che
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Li, Heng
;
Zhang, Zhe-Han
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Chen, Hsiang
;
Wang, Shing-Chung
We report on the design of the geometry and chip size-controlled structures of microscale light-emitting diodes (micro-LEDs) with a shallow-etched oxide-refilled current aperture and their performance. The proposed structure, which combines an indium-tin-oxide layer and an oxide-confined aperture, exhibited not only uniform current distribution but also remarkably tight current confinement. An extremely high injection level of more than 90 kA/cm(2) was achieved in the micro-LED with a 5-mu m aperture. Current spreading and the droop mechanism in the investigated devices were characterized through electroluminescence measurements, optical microscopy, and beam-view imaging. Furthermore, we utilized the beta-model and S-model to elucidate current crowding and the efficiency droop phenomenon in the investigated micro-LEDs. The luminescence results evidenced the highly favorable performance of the fabricated micro-LEDs, which is a result of their more uniform current spreading and lower junction temperature relative to conventional LEDs. Moreover, the maximum endured current density could be further increased by reducing the aperture size of the micro-LEDs. The proposed design, which is expected to be beneficial for the development of high-performance array-based micro-LEDs, is practicable through current state-of-the-art processing techniques. Published by AIP Publishing.
Two-dimensional designed fabrication of subwavelength grating HCG mirror on Silicon-on-insulator
(2016-01-01)
Huang, Shen-Che
;
Hong, Kuo-Bin
;
Lu, Tien-Chang
;
He, Sailing
;
光電工程學系
We designed and fabricated a two dimensional high contrast subwavelength grating (HCG) mirrors. The computer-aided software was employed to verify the structural parameters including grating periods and filling factors. From the optimized simulation results, the designed HCG structure has a wide reflection stopband (reflectivity (R) >90%) of over 200 nm, which centered at telecommunication wavelength. The optimized HCG mirrors were fabricated by electron-beam lithography and inductively coupled plasma process technique. The experimental result was almost consistent with calculated data. This achievement should have an impact on numerous photonic devices helpful attribution to the integrated HCG VCSELs in the future.
ZnO nanoflakes on silver wires with antibacterial effects
(2016-05-01)
Huang, Shen-Che
;
Hsieh, Kun Min
;
Chang, Ting Wei
;
Chen, Yi Cian
;
Yu, Chang-Tze Ricky
ZnO structures were electro-hydrothermally grown on copper and silver wires. To characterize the structures, multiple analyses including field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction and photoluminescence measurements were performed on the ZnO structures on the wires. Results indicate that ZnO nanoflakes were densely deposited on the silver wire but poor ZnO structures were grown on the copper wire. Furthermore, OD 600 antibacterial tests revealed that ZnO flakes on the silver wire exhibited better antibacterial capability than the silver wire without ZnO nanoflakes. Because of possible integration with silver-related materials and flexibility of wire structures, ZnO nanoflake-coated silver wires have potentials for future antiseptic and biomedical applications. (C) 2016 Elsevier Ltd and Techna Group S.r.l. All rights reserved.