Browsing by Author "Lan, Yu-Pin"

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Advantages of Blue LEDs With Graded-Composition AlGaN/GaN Superlattice EBL
(2013-11-01)
Lin, Bing-Cheng
;
Chen, Kuo-Ju
;
Han, Hau-Vei
;
Lan, Yu-Pin
;
Chiu, Ching-Hsueh
InGaN/GaN light-emitting diodes (LEDs) with graded-composition AlGaN/GaN superlattice (SL) electron blocking layer (EBL) were designed and grown by metal-organic chemical vapor deposition. The simulation results demonstrated that the LED with a graded-composition AlGaN/GaN SL EBL have superior hole injection efficiency and lower electron leakage over the LED with a conventional AlGaN EBL or normal AlGaN/GaN SL EBL. Therefore, the efficiency droop can be alleviated to be similar to 20% from maximum at an injection current of 15-120 mA, which is smaller than that for conventional AlGaN EBL (30%). The corresponding experimental results also confirm that the use of a graded-composition AlGaN/GaN SL EBL can markedly enhance the light output power by 60%.
Crossover from polariton lasing to exciton lasing in a strongly coupled ZnO microcavity
(2016-02-03)
Lai, Ying-Yu
;
Chou, Yu-Hsun
;
Lan, Yu-Pin
;
Lu, Tien-Chang
;
Wang, Shing-Chung
Unlike conventional photon lasing, in which the threshold is limited by the population inversion of the electron-hole plasma, the exciton lasing generated by exciton-exciton scattering and the polariton lasing generated by dynamical condensates have received considerable attention in recent years because of the sub-Mott density and low-threshold operation. This paper presents a novel approach to generate both exciton and polariton lasing in a strongly coupled microcavity (MC) and determine the critical driving requirements for simultaneously triggering these two lasing operation in temperature <140 K and large negative polariton-exciton offset (<-133 meV) conditions. In addition, the corresponding lasing behaviors, such as threshold energy, linewidth, phase diagram, and angular dispersion are verified. The results afford a basis from which to understand the complicated lasing mechanisms in strongly coupled MCs and verify a new method with which to trigger dual laser emission based on exciton and polariton.
Effect of InGaN/GaN Multiple Quantum Wells with p-n Quantum Barriers on Efficiency Droop in Blue Light-emitting Diodes
(2013-01-01)
Wang, Sheng-Wen
;
Lin, Da-Wei
;
Lee, Chia-Yu
;
Liu, Che-Yu
;
Lan, Yu-Pin
In this study, the structures of InGaN/GaN multiple quantum wells (MQWs) with p-n quantum barriers in various positions were proposed to investigate the efficiency droop behavior for blue light-emitting diodes (LEDs). The simulated electric field diagrams showed that the quantum well (QW) sandwiched by the p-n quantum barriers had a less electric field than the other QWs due to the original polarization-related electric field was partially balanced off by the built-in electric field of the p-n quantum barriers. In addition, the simulation results demonstrated that by selecting suitable position of p-n quantum barriers, the distribution of carriers could be effectively improved; hence the droop behavior could also be suppressed.
Efficiency and droop improvement in green InGaN/GaN light-emitting diodes on GaN nanorods template with SiO2 nanomasks
(2012-12-03)
Lin, Da-Wei
;
Lee, Chia-Yu
;
Liu, Che-Yu
;
Han, Hau-Vei
;
Lan, Yu-Pin
This study presents the green InGaN/GaN multiple quantum wells light-emitting diodes (LEDs) grown on a GaN nanorods template with SiO2 nanomasks by metal-organic chemical vapor deposition. By nanoscale epitaxial lateral overgrowth, microscale air voids were formed between nanorods and the threading dislocations were efficiently suppressed. The electroluminescence measurement reveals that the LEDs on nanorods template with SiO2 nanomasks suffer less quantum-confined Stark effect and exhibit higher light output power and lower efficiency droop at a high injection current as compared with conventional LEDs. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4768950]
Efficiency and Droop Improvement in InGaN/GaN Light-Emitting Diodes by Selective Carrier Distribution Manipulation
(2012-04-01)
Wang, Chao-Hsun
;
Chang, Shih-Pang
;
Ku, Pu-Hsi
;
Lan, Yu-Pin
;
Lin, Chien-Chung
Efficiency and droop behavior in InGaN/GaN light-emitting diodes (LEDs) are both improved using selectively graded composition multiple quantum barriers (SGQBs). Simulation results show that SGQBs could moderately improve the hole transport in the active region. In the meantime, the spatial distribution overlap between electrons and holes in the active region could also be well considered. Therefore, the radiative recombination of the SGQB LED is more efficient than that of the conventional LED. The overall efficiency and droop behavior are simultaneously improved in the SGQB LED, at both low and high current densities. (C) 2012 The Japan Society of Applied Physics
Efficiency and droop improvement in InGaN/GaN light-emitting diodes by selectively carrier-distribution manipulation
(2012)
Lin, Da-Wei
;
Wang, Chao-Hsun
;
Chang, Shih-Pang
;
Ku, Pu-Hsih
;
Lan, Yu-Pin
Efficiency and droop behavior in InGaN/GaN light-emitting diodes are both improved by selectively-graded-composition multi-quantum barriers (SGQB). Simulation results show that SGQB could moderately improve the hole transport in active region. In the meantime, spatial distribution overlap between electrons and holes in active region could be also well-considered. Therefore, the radiative recombination of SGQB LED is more efficient than that of conventional LED. The overall efficiency and droop behavior are simultaneously improved in SGQB LED, at both low and high current density.
Efficiency improvement of GaN-based ultraviolet light-emitting diodes with reactive plasma deposited AlN nucleation layer on patterned sapphire substrate
(2014-09-16)
Lee, Chia-Yu
;
Tzou, An-Jye
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Lin, Bing-Cheng
;
Lan, Yu-Pin
;
Chiu, Ching-Hsueh
The flip chip ultraviolet light-emitting diodes (FC UV-LEDs) with a wavelength of 365 nm are developed with the ex situ reactive plasma deposited (RPD) AlN nucleation layer on patterned sapphire substrate (PSS) by an atmospheric pressure metal-organic chemical vapor deposition (AP MOCVD). The ex situ RPD AlN nucleation layer can significantly reduce dislocation density and thus improve the crystal quality of the GaN epitaxial layers. Utilizing high-resolution X-ray diffraction, the full width at half maximum of the rocking curve shows that the crystalline quality of the epitaxial layer with the (RPD) AlN nucleation layer is better than that with the low-temperature GaN (LT-GaN) nucleation layer. The threading dislocation density (TDD) is estimated by transmission electron microscopy (TEM), which shows the reduction from 6.8 x 10(7) cm(-2) to 2.6 x 10(7) cm(-2). Furthermore, the light output power (LOP) of the LEDs with the RPD AlN nucleation layer has been improved up to 30 % at a forward current of 350 mA compared to that of the LEDs grown on PSS with conventional LT-GaN nucleation layer.
Enhanced internal quantum efficiency in graphene/InGaN multiple-quantum-well hybrid structures
(2012-08-06)
Huang, Huei-Min
;
Chang, Chiao-Yun
;
Hsu, Yueh-Shan
;
Lu, Tien-Chang
;
Lan, Yu-Pin
The enhanced internal quantum efficiency of InGaN/GaN multiple-quantum-wells (MQWs) structure is demonstrated by paving the graphene layers on the MQWs surface. Compared to the conventional MQWs, the internal quantum efficiency of the graphene/InGaN MQWs hybrid structure exhibits a remarkable 2-fold increase. The high charge carrier density in graphene layer is accounted for the enhanced internal quantum efficiency. Moreover, the negligible photoluminescence emission peak shift with increasing the excitation power as well as the decrease of radiative recombination lifetime are attributed to the reduced quantum-confined Stark effect, which correlates to the screening of the polarization field in the c-plane nitride-based quantum well structure. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4745211]
Enhanced Light Output Power and Growth Mechanism of GaN-Based Light-Emitting Diodes Grown on Cone-Shaped SiO2 Patterned Template
(2013-04-01)
Lin, Da-Wei
;
Huang, Jhih-Kai
;
Lee, Chia-Yu
;
Chang, Ruey-Wen
;
Lan, Yu-Pin
In this study, we successfully transferred the patterns of a cone-shaped patterned sapphire substrate (CPSS) into SiO2 layer to fabricate a cone-shaped SiO2 patterned template by using nanoimprint lithography (NIL). The GaN-based light-emitting diodes (LEDs) were grown on this template by metal-organic chemical vapor deposition (MOCVD). The transmission electron microscopy (TEM) images suggest that the stacking faults formed near the cone-shaped SiO2 patterns during the epitaxial lateral overgrowth (ELOG) can effectively suppress the threading dislocations, which results in an enhancement of internal quantum efficiency. The Monte Carlo ray-tracing simulation reveals that the light extraction efficiency of the LED grown on cone-shaped SiO2 patterned template can be enhanced as compared with the LED grown on CPSS. As a result, the light output power of the LED grown on cone-shaped SiO2 patterned template outperformed the LED grown on CPSS.
Exciton-polaritons study in ZnO-based hybrid microcavities
(2012)
Lan, Yu-Pin
;
Lai, Ying-Yu
;
Huang, Si-Wei
;
Chen, Jun-Rong
;
Wu, Yung-Chi
The characteristics of exciton-polaritons in ZnO-based microcavities (MCs) are demonstrated with a large vacuum Rabi splitting due to large exciton binding energy and oscillator strength. The lower polariton branches (LPBs) can be clearly observed. For low temperature and large negative detuning conditions, a clear polariton relaxation bottleneck in bulk ZnO-based MCs has been observed in angle-resolved photoluminescence measurements from 100 to 353 K at different cavity-exciton detunings. The bottleneck is strongly suppressed with increasing the temperature and pumping power and reducing detuning. This observed results supposed to be due to more efficient phonon-assisted relaxation and a longer radiative lifetime of the polaritons. In addition, the linewidth broadening, blue-shift of the emission peak, and polarization of polariton lasing from below threshold to up threshold are also discussed.
Fabricating GaN-based LEDs on (-201) beta-Ga2O3 substrate via non-continuous/continuous growth between low-temperature undoped-GaN and high-temperature undoped-GaN in atmospheric pressure metal-organic chemical vapor deposition
(2019-10-01)
Lan, Yu-Pin
;
Chen, Yen-Chun
;
Yeh, Yi-Yun
;
Hung, Shun-Ming
;
光電系統研究所
This study demonstrates two approaches to the growth of GaN-based LEDs on (-2 0 1)-oriented beta-Ga2O3 single crystal substrates using metalorganic CVD under atmospheric pressure. One approach induces non-continuous growth between low-temperature undoped-GaN (u-GaN) and high-temperature u-GaN, whereas the other approach induces continuous growth. We observed the following reduction in the FWHM of X-ray diffraction rocking curves: GaN (0 0 2) on (-2 0 1) beta-Ga2O3 substrate (from 464 to 342 arcsec) and GaN (1 0 2) (from 886 to 493 arcsec). An LED with six pairs of InGaN/GaN multiple quantum wells was successfully fabricated on the (-2 0 1) beta-Ga2O3 single crystal substrate. (C) 2019 The Japan Society of Applied Physics
Fabrication and characteristics of a GaN-based microcavity laser with shallow etched mesa
(2014-06-01)
Lai, Ying-Yu
;
Chou, Yu-Hsun
;
Wu, Yu-Sheng
;
Lan, Yu-Pin
;
Lu, Tien-Chang
In this work, we have developed a simple GaN-based microcavity (MC) with an intracavity shallow etched mesa. The textured GaN-based MC incorporated two high-reflectivity dielectric Bragg mirrors and an InGaN/GaN multiple quantum well with a shallow etched mesa as an optical confined structure. Lasing and transverse optical confinement characteristics have been verified by measuring devices with different mesa diameters. A quality factor (Q) of 2600 and a threshold energy of 30 nJ have been observed in a 10-mu m-diameter device. Such a cavity structure could be implanted into electrically pumped GaN vertical-cavity surface-emitting lasers for supporting efficient transverse confinement. (C) 2014 The Japan Society of Applied Physics
Fabrication and characteristics of a GaN-based microcavity laser with shallow etched mesa
(2014-06-01)
Lai, Ying-Yu
;
Chou, Yu-Hsun
;
Wu, Yu-Sheng
;
Lan, Yu-Pin
;
Lu, Tien-Chang
In this work, we have developed a simple GaN-based microcavity (MC) with an intracavity shallow etched mesa. The textured GaN-based MC incorporated two high-reflectivity dielectric Bragg mirrors and an InGaN/GaN multiple quantum well with a shallow etched mesa as an optical confined structure. Lasing and transverse optical confinement characteristics have been verified by measuring devices with different mesa diameters. A quality factor (Q) of 2600 and a threshold energy of 30 nJ have been observed in a 10-mu m-diameter device. Such a cavity structure could be implanted into electrically pumped GaN vertical-cavity surface-emitting lasers for supporting efficient transverse confinement. (C) 2014 The Japan Society of Applied Physics
Ferroelectric Characterization of Hafnium-Oxide-Based Ferroelectric Memories with Remote Nitrogen Plasma Treatments
(2019-01-01)
Lee, You-Ting
;
Chen, Hsuan-Han
;
Tung, Yi-Chun
;
Shih, Bing-Yang
;
Hsiung, Szu-Yen
In this paper, we experimentally demonstrated the advantage of remote nitrogen plasma on improving interface quality of HfO2-based ferroelectric devices. The remote nitrogen plasma not only reduces leakage current of gate stack to appropriately sustain the ferroelectricity during ferroelectric domain switching, but also effectively improve the ferroelectric fatigue to enhance endurance cycling performance.
High Efficiency GaN-based Light Emitting Diodes with Embedded Air Voids/SiO2 Nanomasks
(2012-01-01)
Chiu, Ching-Hsueh
;
Lin, Chien-Chung
;
Han, Hau-Vei
;
Lin, Da-Wei
;
Chen, Yan-Hao
We fabricated high efficiency LEDs with embedded micro-scale air voids and SiO2 nanomask exhibit smaller reverse-bias current and great enhancement of the light output (65% at 20mA) compared with the conventional LEDs.
High efficiency GaN-based light-emitting diodes with embedded air voids/SiO(2) nanomasks
(2012-02-03)
Chiu, Ching-Hsueh
;
Lin, Chien-Chung
;
Han, Hau-Vei
;
Liu, Che-Yu
;
Chen, Yan-Hao
In this paper, the high performance GaN-based light-emitting diodes (LEDs) with embedded microscale air voids and an SiO(2) nanomask by metal-organic chemical vapor deposition (MOCVD) were demonstrated. Microscale air voids and an SiO(2) nanomask were clearly observed at the interface between GaN nanorods (NRs) and the overgrown GaN layer by scanning electron microscopy (SEM). From the reflectance spectra we show strong reflectance differences due to the different refractive index gradient between the GaN grown on the nanotemplate and sapphire. It can increase the light extraction efficiency due to additional light scattering. The transmission electron microscopy (TEM) images show the threading dislocations were suppressed by nanoscale epitaxial lateral overgrowth (NELOG). The LEDs with embedded microscale air voids and an SiO(2) nanomask exhibit smaller reverse-bias current and large enhancement of the light output (65% at 20 mA) compared with conventional LEDs.
High efficiency GaN-based light-emitting diodes with embedded air voids/SiO2 nanomasks
(2012-02-03)
Chiu, Ching-Hsueh
;
Lin, Chien-Chung
;
Han, Hau-Vei
;
Liu, Che-Yu
;
Chen, Yan-Hao
In this paper, the high performance GaN-based light-emitting diodes (LEDs) with embedded microscale air voids and an SiO2 nanomask by metal-organic chemical vapor deposition (MOCVD) were demonstrated. Microscale air voids and an SiO2 nanomask were clearly observed at the interface between GaN nanorods (NRs) and the overgrown GaN layer by scanning electron microscopy (SEM). From the reflectance spectra we show strong reflectance differences due to the different refractive index gradient between the GaN grown on the nanotemplate and sapphire. It can increase the light extraction efficiency due to additional light scattering. The transmission electron microscopy (TEM) images show the threading dislocations were suppressed by nanoscale epitaxial lateral overgrowth (NELOG). The LEDs with embedded microscale air voids and an SiO2 nanomask exhibit smaller reverse-bias current and large enhancement of the light output (65% at 20 mA) compared with conventional LEDs.
High holding voltage segmentation stacking silicon-controlled-rectifier structure with field implant as body ties blocking layer
(2016-04)
Yen, Shiang-Shiou
;
Cheng, Chun-Hu
;
Lan, Yu-Pin
;
Chiu, Yu-Chien
;
Fan, Chia-Chi
High electrostatic discharge (ESD) protection robustness and good transient-induced latchup immunity are two important issues for high voltage integrate circuit application. In this study, we report a high-voltage-n-type-field (HVNF) implantation to act as the body ties blocking layer in segmented topology silicon-controlled-rectifier (SCR) structure in 0.11 mu m 32 V high voltage process. This body ties blocking layer eliminate the elevated triggered voltage in segmented technique. Using a large resistance as shunt resistor in resistor assisted triggered SCRs stacking structure, the double snapback phenomenon is eliminate. The series SCR could be decoupled a sufficient voltage drop to turned-on when a very low current flow through the shunt resistor. The holding voltage and the failure current of 22 V and 3.4 A are achieved in the best condition of segmented topology SCR stacking structure, respectively. It improves the latchup immunity at high voltage ICs application. On the other hand, the triggered voltage almost keep the same value which is identical to SCR single cell without using segmented topology. (C) 2016 The Japan Society of Applied Physics
High holding voltage segmentation stacking silicon-controlled-rectifier structure with field implant as body ties blocking layer
(2016-04-01)
Yen, Shiang-Shiou
;
Cheng, Chun-Hu
;
Lan, Yu-Pin
;
Chiu, Yu-Chien
;
Fan, Chia-Chi
High electrostatic discharge (ESD) protection robustness and good transient-induced latchup immunity are two important issues for high voltage integrate circuit application. In this study, we report a high-voltage-n-type-field (HVNF) implantation to act as the body ties blocking layer in segmented topology silicon-controlled-rectifier (SCR) structure in 0.11 mu m 32 V high voltage process. This body ties blocking layer eliminate the elevated triggered voltage in segmented technique. Using a large resistance as shunt resistor in resistor assisted triggered SCRs stacking structure, the double snapback phenomenon is eliminate. The series SCR could be decoupled a sufficient voltage drop to turned-on when a very low current flow through the shunt resistor. The holding voltage and the failure current of 22 V and 3.4 A are achieved in the best condition of segmented topology SCR stacking structure, respectively. It improves the latchup immunity at high voltage ICs application. On the other hand, the triggered voltage almost keep the same value which is identical to SCR single cell without using segmented topology. (C) 2016 The Japan Society of Applied Physics
High Reflectance Patterned Substrate Designed for Optical Devices
(2015)
Lan, Yu-Pin
;
Wu, Yung-Chi
;
Lin, Da-Wei
;
Hong, Kuo-Bin
;
Lee, Chia-Yu
This article proposed an approach by using patterned sapphire substrate to act as a 2-dimensional distributed Bragg reflector (DBR) mirror to increase the output power of LEDs.