Browsing by Author "Chen, Yu-Chen"

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10% Efficiency Hybrid GaAs/PEDOT:PSS Solar Cells with Monolayer Graphene
(2014-01-01)
Cheng, Kai-Yuan
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Pan, Huai-Te
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Yu, Shu-Cheng
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Weng, Wei-Sheng
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Lai, Yi-Chun
The development of solution-processed hybrid organic-inorganic heterojunction solar cells have provoked increasing research effort due to potential to significantly reduce the fabrication cost of semiconductor solar cells while maintaining the high power conversion efficiency (PCE). With a recent record of GaAs solar cells achieving 28.8% via a wafer lift-off technique, hybrid organic/GaAs solar cells can offer an alternative route to provide more affordable solar power than current semiconductor technologies. In this work, we demonstrate the hybrid devices based on a conductive polymer poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) directly spun-cast on planar gallium arsenide materials. While still lacking for optimized antireflection, the PCE of the best performing device can achieve nearly 10% by introducing the monolayer graphene as transparent electrode. The current progress presents 2-fold enhancement in comparison to a previous record at 5% based on GaAs nanowire templates.
A 135 MHz 542 k Gates High Throughput H.264/AVC Scalable High Profile Decoder
(2012-04-01)
Li, Gwo-Long
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Chen, Yu-Chen
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Liao, Yuan-Hsin
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Hsu, Po-Yuan
;
Wen, Meng-Hsun
To satisfy the requirement of application heterogeneities, the latest H.264/AVC based video coding standard called scalable video coding additional includes temporal, SNR, and spatial scalabilities for frame rate, quality, and frame resolution adaptation. However, these inclusions significantly increase chip design difficulties such as decoding time, memory bandwidth, and area cost. This paper presents an H.264/AVC scalable high profile decoder realization with several optimization techniques to provide high throughput video decoding. For decoding flow, this paper proposes an one-pass macroblock-based quality layer decoding flow for SNR scalability and 71% of external memory bandwidth and 66% of macroblock processing cycles can be saved. For texture padding in interlayer intra prediction, the modified padding flow can save 26% of decoding time. For interlayer predictor design, this paper proposes a centralized concept for accumulation-based calculation of corresponding spatial position, simplified poly-phase interpolator, and efficient motion vector generator to save area cost and decoding time. Furthermore, the residual reconstruction path with the parallelpipeline architecture is also proposed to cope with the additional decoding complexity and thus leads to 54% of gate count savings compared to the traditional serial-pipeline architecture. Finally, the proposed H. 264/AVC scalable high profile decoder design is implemented with 90 nm CMOS technology and it costs 542 k gate count and 39.66 Kbytes on-chip memory while is capable to decode 60 frames/s for CIF+SD480p+HD1080p resolution with three quality layers at 135 MHz operating frequency.
Chirped multilayer quantum-dot mode-locked lasers with dual-wavelength and ground-state lasing emissions
(2019-01-01)
Chen, Yu-Chen
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Hsieh, Pin-Hsien
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Lin, Gray
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電子工程學系及電子研究所
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Department of Electronics Engineering and Institute of Electronics
Monolithic passively mode-locked lasers are investigated based on chirped multi-layer InAs/InGaAs quantum-dot (QD) structure. The forward and backward tracings of light-current characteristics show two kinks and two hysteresis loops. The optical spectra reveal two lasing wavelengths around 1273 and 1230 nm, which are identified as two ground-state emissions of two differently chirped QD layers. The corresponding radio-frequency (RF) spectra of high-speed detector reveal two RF peaks at 16.21 and 16.03 GHz, which are attributed to fundamental mode-locking of two respective wavelengths. The laser pulses are confirmed by optical autocorrelator to exhibit dual-wavelength mode-locking. The pulsed characteristics of two lasing wavelengths are also discussed in terms of operating conditions. (C) 2019 Society of Photo-Optical Instrumentation Engineers (SPIE)
Continuous-Wave Lasing of 1.3-mu m Quantum-Dot Photonic-Crystal Surface-Emitting Lasers
(2018-01-01)
Hsu, Ming-Yang
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Lin, Gray
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Pan, Po-Chou
;
Chen, Yu-Chen
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電子工程學系及電子研究所
Fabrication of electrically injected quantum-dot photonic-crystal (PC) surface-emitting lasers (SELs) is simplified by deposition of indium-tin-oxide over "PC slab-on-substrate" structure. Temperature-insensitive threshold current behavior is exhibited for negatively detuned PCSEL where continuous-wave lasing emission at 1308.4 nm is demonstrated for the first time.
Dual-wavelength mode-locking of novel chirped multilayer quantum-dot lasers
(2016)
Chiang, Chun-Ping
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Lin, Gray
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Chen, Yu-Chen
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Cheng, Hsu-Chieh
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電子工程學系及電子研究所
Monolithic passively mode-locked lasers are investigated based on chirped multilayer InAs/InGaAs QDs. Three chirped wavelengths, with stacking numbers of 2, 3 and 5 layers, are designed with capped InGaAs thickness of 4, 3 and 1 nm, respectively. The ridge-waveguide devices of 5-mu m width and 3-mm length are fabricated to have absorber-to-gain length ratio of 1:9. A curve tracer is used to analyze the hysteresis on the light-current curve. Two kinks in the L-I curve are observed at threshold current near 50 mA and at higher current of about 150 mA. The lasing wavelength just above threshold is centered at 1268 nm and the RF spectrum of mode-locking is peaked at 13.32 GHz. At well above threshold of 200 mA, another RF peak at 13.21 GHz occurs that corresponds to shorter lasing wavelength around 1233 nm. The two lasing wavelengths are originated from ground-state transitions of two groups of InAs/InGaAs QDs. Simultaneous dual-wavelength mode-locking is therefore achieved at rather low forward current and low reverse bias by incorporating this novel design of QD structure.
Effects of layer sequence and postdeposition annealing temperature on performance of La2O3 and HfO2 multilayer composite oxides on In0.53Ga0.47As for MOS capacitor application
(2014-03-01)
Wu, Wen-Hao
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Lin, Yueh-Chin
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Chuang, Ting-Wei
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Chen, Yu-Chen
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Hou, Tzu-Ching
In this paper, we report on high-k composite oxides that are formed by depositing multiple layers of HfO2 and La2O3 on In0.53Ga0.47As for MOS device application. Both multilayer HfO2 (0.8 nm)/La2O3 (0.8 nm)/In0.53Ga0.47As and La2O3 (0.8 nm)/HfO2 (0.8 nm)/In0.53Ga0.47As MOS structures were investigated. The effects of oxide thickness and postdeposition annealing (PDA) temperature on the interface properties of the composite oxide MOS capacitors were studied. It was found that a low CET of 1.41 nm at 1 kHz was achieved using three-layer composite oxides. On the other hand, a small frequency dispersion of 2.8% and an excellent D-It of 7.0 Chi 10(11)cm(-2).eV(-1) can be achieved using multiple layers of La2O3 (0.8 nm) and HfO2 (0.8 nm) on the In0.53Ga0.47As MOS capacitor with optimum thermal treatment and layer thickness. (C) 2014 The Japan Society of Applied Physics
Efficient Inter-layer Prediction Hardware Design with Extended Spatial Scalability for H.264/AVC Scalable Extension
(2010)
Chen, Yu-Chen
;
Li, Gwo-Long
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Chang, Tian-Sheuan
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電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
To support inter-layer prediction with arbitrary frame resolution ratio between successive spatial layers, the scalable video coding (SVC) adopts the mechanism of extended spatial scalability (ESS) to achieve it but with noticeable hardware implementation complexity due to the numerous multiplication operations. Therefore, this paper proposes a hardware efficient inter-layer prediction architecture design with ESS by means of accumulator approach. In addition, an area efficient inter-layer interpolator architecture and simplified transform block identification scheme are also proposed to further reduce hardware costs. Simulation results demonstrate that our proposed architecture can significantly save gate count when compared to direct implementation approach.
Large Photoresponsivity in the Amorphous-TiO2/SrRuO(3)Heterostructure
(1970-01-01)
Liu, Heng-Jui
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Huang, Chin-Han
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Chen, Cheng-Ying
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Hsiao, Sheng-Wei
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Chen, You-Sheng
Thin-film heterostructures are effective in enhancing the performance or triggering novel physical phenomena of optoelectronic applications. For example, the epitaxial heterostructures of ultraviolet-light-sensitive TiO(2)with metallic SrRuO(3)can acquire visible-light functionalities using the hot carrier injection mechanism. Therefore, the TiO2/SrRuO(3)heterostructure system has recently attracted increasing interest. Herein, the amorphous-TiO2/SrRuO(3)heterostructure is fabricated and compared to the epitaxial TiO2/SrRuO3. As opposed to the occurrence of the visible-light photovoltaic effect in the epitaxial TiO2/SrRuO3, the amorphous-TiO2/SrRuO(3)heterostructure herein exhibits different optoelectronic functionality, specifically the photoresistor behavior. The amorphous-TiO2/SrRuO(3)heterostructure achieves a photoresponsivity of 6.56 A W(-1)at 1 V. Such a performance is hardly obtained in typical oxide-based photoresistors. The analyses of the crystalline and electronic structures show that it is due to the defect-induced high electron doping in the amorphous TiO(2)with hot carrier injection mechanism. This study discusses the correlation between the hot carrier injection and band diagram, which provides more degrees of freedom in designing potential optoelectronic devices.
Magnetic and Metal Binding Structural Analysis of Mn,Zn-Metallothionein-Green Fluorescence Fusion Protein
(2012-01-31)
Chen, Ting-Kai
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Lin, Yin-Chih
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Chen, Yu-Chen
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Chen, Yen-Lin
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Tseng, Wei-Lun
Relationship between Threshold Gain and Bragg Detuning in Photonic-Crystal Surface-Emitting Lasers
(2019-01-01)
Li, Zong-Lin
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Lin, Shen-Chieh
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Chen, Yu-Chen
;
Lin, Gray
;
電子工程學系及電子研究所
The device characteristics of GaSb-based mid-infrared (MIR) photonic-crystal (PC) surface-emitting lasers (SELs) were investigated with respect to depths of etched PC holes. Measurement of below-threshold emission spectra identifies the bandgap as well as band-edge modes. The bandgap separation, which is a function of feedback coupling, increases with increasing depth. From within, the Bragg frequencies and their detuning from lasing frequencies can be determined. Moreover, with increasing depth, the threshold pumping density decreases exponentially to a saturation level, which is assigned to minimum device modal gain of certain value. The relative threshold gain is then plotted as a function of normalized frequency detuning. The gain-detuning relationship of PCSELs is similar to that of one-dimensional (1D) distributed feedback (DFB) lasers.
Reliability of High Power Semiconductor Lasers on Bonding and Mounting Design
(2015)
Chen, Yu-Chen
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Lin, Gray
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電子工程學系及電子研究所
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Department of Electronics Engineering and Institute of Electronics
Reliability of high-power semiconductor lasers can be underestimated because of imperfect bonding and improper mounting. The C-mount package of Cu material is replaced with CuW material and high power laser chips are bonded above without AlN submount. For the burn-in test, liquid-metal alloy is applied between C-mount and heatsink to improve thermal contact. The estimated lifetime of 4 W, 808 nm lasers is therefore greatly increased to over 3600 hours.
Temperature Dependence of Electrically Injected Quantum-Dot Photonic-Crystal Surface-Emitting Lasers
(2018-01-01)
Hsu, Ming-Yang
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Lin, Gray
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Chen, Yu-Chen
;
Pan, Chien-Hung
;
電子工程學系及電子研究所
We have simplified fabrication of electrically injected quantum-dot photonic-crystal surface-emitting lasers and demonstrated lasing emissions at 1313 nm. Excellent threshold temperature characteristics was exhibited in range of 20 similar to 45 degrees C with characteristics temperature of almost infinity.