Browsing by Author "Laih, Li-Wen"

Now showing 1 - 5 of 5

Design and fabrication of temperature-insensitive InGaP-InGaAlP resonant-cavity light-emitting diodes
(2006-07-01)
Chang, Yi-An
;
Yu, Chun-Lung
;
Wu, I-Tsung
;
Kuo, Hao-Chung
;
Lu, Tien-Chang
Visible InGaP-InGaAlP resonant-cavity light-emitting diodes with low-temperature sensitivity output characteristics were demonstrated. By means of widening the resonant cavity to a thickness of three wavelength (3 A), the degree of power variation between 25 degrees C and 95 degrees C for the devices biased at 20 mA was apparently reduced from -2.1 dB for the standard structure design (1 - lambda avity) to -0.6 dB. An output power of 2.4 mW was achieved at 70 mA. The external quantum efficiency achieved a maximum of 3% at 13 mA and dropped slowly with increased current for the device. The external quantum efficiency at 20 mA dropped only 14% with elevated temperature from 25 degrees C to 95 degrees C. The current dependent far-field patterns also showed that the emission always took place perfectly in the normal direction, which was suitable for plastic fiber data transmission.
Efficiency Improvement of Single-Junction In(0.5)Ga(0.5)P Solar Cell with Compositional Grading p-Emitter/Window Capping Configuration
(2010-01-01)
Chang, Yi-An
;
Kuo, Hao-Chung
;
Lu, Tien-Chang
;
Lai, Fang-I
;
Kuo, Shou-Yi
In this study a novel p-emitter/window capping configuration design applied to a p(+)-n In(0.5)Ga(0.5)P solar cell is developed. By grading the Ga and Al compositions in the interface between the p-In(0.5)Ga(0.5)P emitter and p-In(0.5)Al(0.5)P window layers, the output characteristics of the p(+)-n In(0.5)Ga(0.5)P solar cell are improved. It is found that the photoluminescence (PL) intensity is increased and the minority carrier lifetime obtained from room-temperature time-resolved (TR) PL measurement can be increased from 5.3 ns of the typical design to 7.0 ns, indicating that the application of compositional grading can improve crystal quality and the interface becomes smoother, thus reducing the nonradiative recombination losses. Both the short-circuit current and open-circuit voltage are increased correspondingly and the conversion efficiency is improved from 14.57% of the typical design to 15.32% of the new p-emitter/window configuration under one-sun air-mass 1.5 global illumination. (C) 2010 The Japan Society of Applied Physics
Efficiency Improvement of Single-Junction In0.5Ga0.5P Solar Cell with Compositional Grading p-Emitter/Window Capping Configuration
(2010-01-01)
Chang, Yi-An
;
Kuo, Hao-Chung
;
Lu, Tien-Chang
;
Lai, Fang-I
;
Kuo, Shou-Yi
In this study a novel p-emitter/window capping configuration design applied to a p(+)-n In0.5Ga0.5P solar cell is developed. By grading the Ga and Al compositions in the interface between the p-In0.5Ga0.5P emitter and p-In0.5Al0.5P window layers, the output characteristics of the p(+)-n In0.5Ga0.5P solar cell are improved. It is found that the photoluminescence (PL) intensity is increased and the minority carrier lifetime obtained from room-temperature time-resolved (TR) PL measurement can be increased from 5.3 ns of the typical design to 7.0 ns, indicating that the application of compositional grading can improve crystal quality and the interface becomes smoother, thus reducing the nonradiative recombination losses. Both the short-circuit current and open-circuit voltage are increased correspondingly and the conversion efficiency is improved from 14.57% of the typical design to 15.32% of the new p-emitter/window configuration under one-sun air-mass 1.5 global illumination. (C) 2010 The Japan Society of Applied Physics
Fabrication and Characterization of Temperature Insensitive 660-nm Resonant-Cavity LEDs
(2008-07-01)
Chen, Jun-Rong
;
Ko, Tsung-Shine
;
Lu, Tien-Chang
;
Chang, Yi-An
;
Kuo, Hao-Chung
InGaP/AIGaInP 660-nm resonant-cavity light-emitting diodes (RCLEDs) with stable temperature characteristics have been achieved by extending the resonant cavity length from one optical wavelength (1 lambda) to three optical wavelengths (3 lambda) and tripling the number of quantum wells. When the operation temperature increases from 25 degrees C to 95 degrees C, the degree of power variation at 20 mA is reduced from -2.1 dB to -0.6 dB for the conventional 1-lambda cavity RCLEDs and 3-lambda cavity RCLEDs, respectively. In order to interpret the temperature-dependent experimental results, advanced device simulation is applied to model the RCLEDs with different cavity designs. According to the numerical simulation results, we deduce that the stable temperature-dependent output performance should originate from the reduction of electron leakage current and thermally enhanced hole transport for the 3-lambda cavity AIGaInP RCLEDs.
The carrier blocking effect on 850 nm InAlGaAs/AlGaAs vertical-cavity surface-emitting lasers
(2006-10-01)
Chang, Yi-An
;
Ko, Tsung-Shine
;
Chen, Jun-Rong
;
Lai, Fang-I
;
Yu, Chun-Lung
In this study, the carrier blocking effect on 850 nm InAlGaAs/AlGaAs vertical-cavity surface-emitting layers (VCSELs) was theoretically and experimentally investigated. By means of inserting a high-bandgap electron blocking layer, which was either 10 nm thick Al0.75Ga0.25As or 13 nm thick Al0.9Ga0.1As, on the p-side of a quantum-well active region, the laser output performance was theoretically found to be improved. VCSELs with and without an electron blocking layer were also experimentally demonstrated. It was found that the threshold current was reduced from 1.47 to 1.33 mA and the slope efficiency was increased from 0.37 to 0.53 mW mA(-1) by inserting a 10 nm thick Al0.75Ga0.25As electron blocking layer. Also, the device became less sensitive to the device temperature, where the amount of increase in the threshold current at an elevated temperature of 95 degrees C was only 0.27 mA and the slope efficiency dropped by only 24.5%. A peak frequency response of nearly 9 GHz at 5 mA, measured from relative intensity noise (RIN), was obtained in these VCSEL devices.