Browsing by Author "Wang, Shing-Chung"

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A star-ring-bus architecture for WDM fiber-wireless system
(2006-01-01)
Chiou, Hung-Yu
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Peng, Peng-Chun
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Feng, Kai-Ming
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Peng, Wei-Ren
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Chen, JyeHong
A self-healing star-ring-bus architecture for high-capacity WDM fiber-wireless system is proposed and verified experimentally. This architecture can provide reliable, flexible, and robust characteristics for large radio terminals. (C) 2006 Optical Society of America.
A Study of Mechanical Lift-Off Technology for High-Efficiency Vertical LEDs Using Micro-Porous GaN Template
(2013-01-01)
Lee, Chia-Yu
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Lin, Da-Wei
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Liu, Che-Yu
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Hsu, Shih-Chieh
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Kuo, Hao-Chung
The high efficiency vertical light emitting diodes (V-LEDs) using mechanical lift-off with Micro-Porous GaN template formed by high temperature molten KOH wet etching process were demonstrated. The average threading dislocation density (TDD) of u-GaN after regrowth was estimated by transmission electron microscopy (TEM) reduced from 2x10(9) to 1x10(8) cm(2). The sapphire substrate was easily removed by mechanical lift-off during wafer bonding process. The light output of V-LEDs are greatly enhanced by 100% compared with Conventional-LEDs at an operating current of 20mA due to the high quality thin GaN and excellent heating dissipation.
Abnormal polarization switching phenomenon in a-plane Al(x)Ga(1-x)N
(2011-01-01)
Huang, Huei-Min
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Huang, Hung-Hsun
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Wu, Yuh-Renn
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Lu, Tien-Chang
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Kuo, Hao-Chung
The a-plane Al(x)Ga(1-x)N layers show abnormal optical polarization switching behavior. This phenomenon can be well characterized by the assumption of the lambertian-like radiation pattern and simulated by utilizing the 6 x 6 k . p model. (C) 2010 Optical Society of America
Abnormal polarization switching phenomenon in a-plane AlxGa1-xN
(2011-01-01)
Huang, Huei-Min
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Huang, Hung-Hsun
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Wu, Yuh-Renn
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Lu, Tien-Chang
;
Kuo, Hao-Chung
The a-plane AlxGa1-xN layers show abnormal optical polarization switching behavior. This phenomenon can be well characterized by the assumption of the lambertian-like radiation pattern and simulated by utilizing the 6 x 6 k . p model. (C) 2010 Optical Society of America
AlGaN/GaN multiple quantum wells grown by using atomic layer deposition technique
(2008)
Lo, Ming-Hua
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Li, Zhen-Yu
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Chen, Shih-Wei
;
Hong, Jhih-Cang
;
Lu, Ting-Chang
We report the successful growth of high quality ultraviolet (UV) AlGaN/GaN multiple quantum wells (MQWs) structure using atomic layer deposition (ALD) technique. The AlGaN/GaN MQW sample grown on the sapphire substrate consisted of three GaN QWs and four AlGaN barriers comprised AlN/GaN superlattices (SLs). From atomic force microscope measurement, the root-mean-square value of the surface morphology was only 0.35 nm, and no crack was found on the surface. The dislocation density was estimated to be as low as 2x10(8) cm(-2). X-ray and transmission electron microscope data show the grown MQW has shape interface with good periodicity. The sample has a deep UV photoluminescence emission at 334 nm (3.71 eV) with a very narrow linewidth of 45 meV at 13K. The cathodoluminescence image show fairly uniform luminescence pattern at room temperature. In conclusion, the AlGaN/GaN MQW grown by ALD technique should be useful for providing high crystalline quality AlGaN/GaN-based MQW for fabrication of AlGaN/GaN-based UV light emitting devices such as light emitting diodes and lasers.
Angular-resolved Lasing Characteristics at Different Band Edges in GaN Photonic Crystal Surface Emitting Lasers
(2010)
Chen, Shih-Wei
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Lu, Tien-Chang
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Hou, Yun-Ju
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Liu, Ting-Chun
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Kuo, Hao-Chung
We successfully demonstrated and analyzed the angular-resolved characteristics of GaN-based photonic-crystal surface emitting lasers at different band edges (Gamma, K, and M), showing specific lasing angles in measured dispersion diagram. (C) 2010 Optical Society of America
Blue GaN-based surface-emitting lasers incorporating a sub-wavelength high contrast grating
(2013-01-01)
Wu, Tzeng-Tsong
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Wu, Shu-Hsien
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Chen, Hao-Wen
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Lu, Tien-Chang
;
Wang, Shing-Chung
Blue GaN-based surface-emitting lasers incorporating a sub-wavelength high contrast grating were reported. The laser characteristics such as threshold energy, degree of polarization and divergence angle were measured to be 0.56 mJ/cm(2), 73% and 12 degrees. (C) 2013 Optical Society of America
Carrier localization degree of In(0.2)Ga(0.8)N/GaN multiple quantum wells grown on vicinal sapphire substrates
(2009-01-01)
Li, Zhen-Yu
;
Lo, Ming-Hua
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Chiu, Ching-Hua
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Lin, Po-Chun
;
Lu, Tien-Chang
In this work, we have grown In(0.2)Ga(0.8)N/GaN multiple quantum well (MQWs) epitaxial structure on vicinal sapphire substrates by low pressure metal-organic chemical vapor deposition and investigated the relationship between carrier localization degree and vicinal angles of sapphire substrates. The optical analysis confirmed that the In(0.2)Ga(0.8)N/GaN MQWs grown on 0.2 degrees-off sapphire substrate exhibited the smallest carrier localization degree and more ordered In(0.2)Ga(0.8)N/GaN MQW structure. In addition, mechanisms for carrier localization in In(0.2)Ga(0.8)N/GaN MQWs grown on vicinal substrate were discussed based on the results obtained from the power and temperature dependent photoluminescence measurements. The Raman spectrum showing the in-plane compressive stress of the GaN epitaxial structures grown on vicinal sapphire substrates revealed the relation between the dislocation density and the carrier localization degree in MQWs. From transmission electron microscopy images, the threading dislocation density (TDD) of In(0.2)Ga(0.8)N/GaN MQWs grown on 0.2 vicinal sapphire substrate at the bottom of n-GaN layer was about 9.4 X 10(8) cm(-2) and reduced to 3.0 X 10(8) cm(-2) at the top of n-GaN layer. We also obtained the TDD of 5.6 X 10(7) cm(-2) in the MQW region and only 1.0 X 10(7) cm(-2) in the p-GaN region. Based on the results mentioned above, 0.2 degrees-off substrate can offer In(0.2)Ga(0.8)N/GaN MQW blue light-emitting diode structures with benefits, such as high crystal quality, low defects, and small carrier localization degree. (C) 2009 American Institute of Physics. (DOI: 10.1063/1.3055264)
Carrier localization degree of In0.2Ga0.8N/GaN multiple quantum wells grown on vicinal sapphire substrates
(2009-01-01)
Li, Zhen-Yu
;
Lo, Ming-Hua
;
Chiu, Ching-Hua
;
Lin, Po-Chun
;
Lu, Tien-Chang
In this work, we have grown In0.2Ga0.8N/GaN multiple quantum well (MQWs) epitaxial structure on vicinal sapphire substrates by low pressure metal-organic chemical vapor deposition and investigated the relationship between carrier localization degree and vicinal angles of sapphire substrates. The optical analysis confirmed that the In0.2Ga0.8N/GaN MQWs grown on 0.2 degrees-off sapphire substrate exhibited the smallest carrier localization degree and more ordered In0.2Ga0.8N/GaN MQW structure. In addition, mechanisms for carrier localization in In0.2Ga0.8N/GaN MQWs grown on vicinal substrate were discussed based on the results obtained from the power and temperature dependent photoluminescence measurements. The Raman spectrum showing the in-plane compressive stress of the GaN epitaxial structures grown on vicinal sapphire substrates revealed the relation between the dislocation density and the carrier localization degree in MQWs. From transmission electron microscopy images, the threading dislocation density (TDD) of In0.2Ga0.8N/GaN MQWs grown on 0.2 vicinal sapphire substrate at the bottom of n-GaN layer was about 9.4 X 10(8) cm(-2) and reduced to 3.0 X 10(8) cm(-2) at the top of n-GaN layer. We also obtained the TDD of 5.6 X 10(7) cm(-2) in the MQW region and only 1.0 X 10(7) cm(-2) in the p-GaN region. Based on the results mentioned above, 0.2 degrees-off substrate can offer In0.2Ga0.8N/GaN MQW blue light-emitting diode structures with benefits, such as high crystal quality, low defects, and small carrier localization degree. (C) 2009 American Institute of Physics. (DOI: 10.1063/1.3055264)
Characteristics of a-Plane Green Light-Emitting Diode Grown on r-Plane Sapphire
(2009-08-15)
Ling, Shih-Chun
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Wang, Te-Chung
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Chen, Jun-Rong
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Liu, Po-Chun
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Ko, Tsung-Shine
In this work, we have successfully grown a-plane green light-emitting diodes (LEDs) on r-plane sapphire and investigated the device characteristics of a-plane green LEDs. The apparent emission polarization anisotropy was observed and the polarization degree was as high as 67.4%. In addition, the electroluminescence (EL) spectra first revealed a wavelength blue-shift with increasing drive current to 20 mA, which could be attributed to the band-filling effect, and then the EL peak become constant. The current-voltage curve showed the forward voltage of a-plane LED grown on r-plane sapphire substrate was 3.43 V and the differential series resistance was measured to be about 24 Omega as 20-mA injected current. Furthermore, the output power was 240 mu W at 100-mA drive current.
Characteristics of an Electrically Pumped GaN-based Microcavity Light Emitter with an AlN Current Blocking Layer
(2012)
Cheng, Bo-Siao
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Wu, Tzeng-Tsong
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Lai, Ying-You
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Wu, Yun-Lin
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Chen, Cheng-Hung
We demonstrate a GaN-based microcavity light emitter (MCLE) with an AlN current blocking layer. An AlN layer is inserted on the InGaN/GaN multiple quantum wells as a current blocking layer and an optical confinement layer. (C)2011 Optical Society of America
Characteristics of Current-Injected GaN-Based Vertical-Cavity Surface-Emitting Lasers
(2011-11-01)
Lu, Tien-Chang
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Wu, Tzeng-Tsong
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Chen, Shih-Wei
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Tu, Po-Min
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Li, Zhen-Yu
This paper reviews the fabrication technology and performance characteristics of current-injected GaN-based vertical-cavity surface-emitting lasers (VCSELs) with hybrid distributed Bragg reflectors (DBRs). The GaN-based VCSEL consists of a ten-pair Ta(2)O(5)/SiO(2) top DBR, a 7 lambda-thick optical cavity embedded with 10 InGaN/GaN multiquantum wells, and a 29-pair AlN/GaN bottom DBR. Lasing action is observed under continuous-wave operation at room temperature. The laser characteristics, such as temperature-dependent laser threshold current, emission wavelength, and spontaneous emission coupling factors, have been measured and discussed.
Characteristics of exciton-polaritons in ZnO-based hybrid microcavities
(2011-02-28)
Chen, Jun-Rong
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Lu, Tien-Chang
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Wu, Yung-Chi
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Lin, Shiang-Chi
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Hsieh, Wen-Feng
Wide bandgap semiconductors are promising materials for the development of polariton-based optoelectronic devices operating at room temperature (RT). We report the characteristics of ZnO-based microcavities (MCs) in the strong coupling regime at RT with a vacuum Rabi splitting of 72 meV. The impact of scattering states of excitons on polariton dispersion is investigated. Only the lower polariton branches (LPBs) can be clearly observed in ZnO MCs since the large vacuum Rabi splitting pushes the upper polariton branches (UPBs) into the scattering absorption states in the ZnO bulk active region. In addition, we systematically investigate the polariton relaxation bottleneck in bulk ZnO-based MCs. Angle-resolved photoluminescence measurements are performed from 100 to 300 K for different cavity-exciton detunings. A clear polariton relaxation bottleneck is observed at low temperature and large negative cavity detuning conditions. The bottleneck is suppressed with increasing temperature and decreasing detuning, due to more efficient phonon-assisted relaxation and a longer radiative lifetime of the polaritons. (C) 2011 Optical Society of America
Characteristics of GaN-based Vertical Cavity Surface Emitting Lasers with Hybrid Mirrors
(2011)
Lu, Tien-Chang
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Cheng, Bo Siao
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Wu, Tzeng-Tsong
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Chen, Shih-Wei
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Chen, Chien-Kang
We demonstrated CW current injection of GaN VCSELs with hybrid mirrors at room temperature. The laser characteristics, such as temperature dependent laser threshold current, spontaneous emission coupling factors, have been measured and discussed. (C)2011 Optical Society of America
Characteristics of ultraviolet nonpolar InGaN/GaN light-emitting diodes using trench epitaxial lateral overgrowth technology
(2007)
Ling, Shih-Chun
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Wang, Te-Chung
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Ko, Tsung-Shine
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Lu, Tien-Chang
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Kuo, Hao-Chung
Ultraviolet nonpolar InGaN/GaN light-emitting diodes were grown on trench epitaxial lateral overgrowth (TELOG) a-plane GaN template by metalorganic chemical vapor deposition. Electroluminescence measurements revealed main peak at 373 nm when injection current was 40 mA. Furthermore, cathodeluminescence observed the low-defect density wings emitted 373 run peak and the TELOG coalescence areas emitted 443 nm due to different incorporation of indium, Meanwhile, polarization measurement shown a degree of ultraviolet peak is 28.7%.
Characteristics of ultraviolet nonpolar InGaN/GaN light-emitting diodes using trench epitaxial lateral overgrowth technology
(2008-04-01)
Ling, Shih-Chun
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Wang, Te-Chung
;
Ko, Tsung-Shine
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Lu, Tien-Chang
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Kuo, Hao-Chung
Ultraviolet nonpolar InGaN/GaN light-emitting diodes grown on trench epitaxial lateral overgrowth (TELOG) a-plane GaN template by metalorganic chemical vapor deposition were fabricated. Two emission peaks at 373 and 443 nm are observed from each fabricated device. The double emission peaks feature is identified by cathodoluminescence images, which show that the ultraviolet peak is emitted from the low-defect density wings on the TELOG and the blue peak is emitted from the TELOG-coalesced seed areas due to different incorporation of indium. The L-I-V diagram revealed that there are leakage current pathways due to the many threading dislocations in seed regions, and that the output power reached 0.2 mW at 140 mA. Two electroluminescence (EL) peaks are observed simultaneously when the driving current is below 50 mA. However, the EL peak at 373 nm dominates when current is above 50 mA. In addition, the degree of polarization of the ultraviolet peak was measured and found to be 28.7%. (C) 2008 Elsevier B.V. All rights reserved.
Characterization of a-plane green light-emitting diodes using nanorod lateral overgrowth
(2010)
Ling, Shih-Chun
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Chang, Shih-Pang
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Lu, Tien-Chang
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Kuo, Hao-Chung
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Wang, Shing-Chung
We have demonstrated nanorod lateral overgrowth to reduce dislocation density in a-plane GaN. Subsequently, we grow green a-plane light-emitting diodes using nanorod lateral overgrowth. Output power of 0.5 mW was measured at 20 mA. (C)2010 Optical Society of America
Characterization of spatial manipulation on ZnO nanocomposites consisting of Au nanoparticles, a graphene layer, and ZnO nanorods
(2018-01-01)
Huang, Shen-Che
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Lu, Chien-Cheng
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Su, Wei-Ming
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Weng, Chen-Yuan
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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.
Composition Dependence of Infrared Optical Phonon Modes in AlGaN Epilayers Grown on Sapphire Substrates
(2008)
Chen, Jun-Rong
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Lu, Tien-Chang
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Kuo, Hao-Chung
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Wang, Shing-Chung
;
光電工程學系
We reported the systematical study of optical anisotropy of Al(x)Ga(1-x)N epitaxial films grown on sapphire using FTIR measurements. The experimental data can be theoretically fitted by employing a four-phase layered model. Several specific absorption dips were observed when the aluminum composition is larger than 24%. The dip intensity increases with the aluminum compositions. According to the reciprocal space map measurements, these dips may be induced due to the effects of strain relaxation in AlGaN epitaxial layers.
Continuous wave operation of current injected GaN vertical cavity surface emitting lasers at room temperature
(2010-08-16)
Lu, Tien-Chang
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Chen, Shih-Wei
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Wu, Tzeng-Tsong
;
Tu, Po-Min
;
Chen, Chien-Kang
We report the demonstration of the continuous wave laser action on GaN-based vertical cavity surface emitting lasers at room temperature. The laser structure consists of a ten-pair Ta(2)O(5)/SiO(2) distributed Bragg reflector (DBR), a 7 lambda-thick optical cavity, ten-pairs InGaN/GaN multiquantum wells with an AlGaN electron blocking layer, and a 29-pair AlN/GaN DBR. The laser has a threshold current of about 9.7 mA corresponding to the current density of about 12.4 kA/cm(2) and a turn-on voltage about 4.3 V at 300 K. The lasing wavelength was 412 nm with a linewidth of about 0.5 nm. A spontaneous emission coupling efficiency factor of about 5x10(-3) and the degree of polarization of about 55% were measured, respectively. The laser beam has a narrow divergence angle of about 8 degrees. (C) 2010 American Institute of Physics. [doi:10.1063/1.3483133]