Browsing by Author "Yu, Chun-Lung"

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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.
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.