Browsing by Author "Kuo, HC"

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1.3 mu m quantum dot vertical-cavity surface-emitting laser with external light injection
(2005-10-27)
Peng, PC
;
Chang, YH
;
Kuo, HC
;
Tsai, WK
;
Lin, G
A 1.3 mu m quantum dot vertical-cavity surface-emitting laser (QD VCSEL) with external light injection is presented, having been experimentally demonstrated. The QD VCSEL is fabricated on GaAs substrate. The 3 dB frequency response of the QD VCSEL based on the TO-Can package is enhanced from the free-running 1.75 to 7.44 GHz with the light injection technique.
1.3-mu m InAs-InGaAs quantum-dot vertical-cavity surface-emitting laser with fully doped DBRs grown by MBE
(2006-01-01)
Yu, HC
;
Wang, JS
;
Su, YK
;
Chang, SJ
;
Lai, FI
We report InAs-InGaAs quantum-dot vertical-cavity surface-emitting lasers (VCSELs) grown by molecular beam epitaxy with fully doped n- and p-doped AlGaAs distributed Bragg reflectors and including an AlAs layer to form a current and waveguiding aperture. The metal contacts are deposited on a topmost p(+) (GaAs)-Ga-. contact layer and on the bottom surface of the n(+)-GaAs substrate. This conventional selectively oxidized top-emitting device configuration avoids the added complexity of fabricating intracavity or coplanar ohmic contacts. The VCSELs operate continuous-wave at room temperature with peak output powers of 0.33 mW and differential slope efficiencies up to 0.23 W/A. The peak lasing wavelengths are near 1.275 mu m, with a sidemode suppression ratio of 28 dB.
10 Gb/s single-mode vertical-cavity surface-emitting laser with large aperture and oxygen implantation
(2004-08-01)
Lai, FI
;
Hsueh, TH
;
Chang, YH
;
Kuo, HC
;
Wang, SC
High-speed single transverse mode 850 nm vertical cavity surface emitting lasers (VCSELs) with large emission aperture with a diameter of 8 Am were fabricated. These VCSELs exhibit good performance with threshold currents of 1.5 mA, a single transverse mode emission within the full operational range and a maximum output power of 3.8 mW. The large aperture is advantageous to these VCSELs with a smaller dynamic resistance (60 Omega) than that of conventional single-mode VCSEL. These single-mode VCSELs also demonstrate superior high-speed performance up to 10 Gb s(-1).
10 Gbps InGaAs : Sb-G-aAs-GaAsP quantum well vertical cavity surface emitting lasers with 1.27 mu m emission wavelengths
(2005-04-01)
Chang, YH
;
Kuo, HC
;
Chang, YA
;
Chu, JT
;
Tsai, MY
InGaAs:Sb-GaAs-GaAsP vertical cavity surface emitting lasers (VCSELs) with 1.27 mu m emission wavelength were grown by metal-organic chemical vapor deposition (MOCVD) and exhibited excellent performance and temperature stability. The threshold current changes from 1.8 to 1.1 mA and the slope efficiency falls less than similar to 35% as the temperature is increased from room temperature to 70 degrees C. With a bias current of only 5 mA, the 3 dB modulation frequency response was measured to be 8.36GHz, which is appropriate for 10Gb/s operation. The maximal bandwidth is measured to be 10.7GHz With a modulation current efficiency factor (MCEF) of similar to 5.25 GHz/(mA) 1/2. Bit error rates of less than 10(-12) are demonstrated for 10 Gb/s data transmission from 25 degrees C to 70'C. We also accumulated life test data up to 1000 h at 70 degrees C/10 mA.
10Gbps operation of a metamorphic InGaP buffered In0.53Ga0.47As p-i-n photodetector grown on GaAs substrate - art. no. 602023
(2005)
Liao, YS
;
Lin, GR
;
Lin, CK
;
Chu, YS
;
Kuo, HC
A novel top-illuminated In0.53Ga0.47As p-i-n photodiodes (MM-PINPD) grown on GaAs substrate by using a linearly graded metamorphic InxGa1-xP (x graded from 0.49 to 1) buffer layer has been demonstrated on the SONET OC-192 receiving performance. With a cost-efficient TO-46 package, the MM-PINPD at data rate of 10 Gbit/s can be obtained at minimum optical power of -19.5 dBm. At wavelength of 1550nm, the dark current, optical responsivities, noise equivalent power, and operational bandwidth of the MM-PIND with aperture diameter of 60 mu m are 13 pA, 0.6 A/W, 3.4 x 10(-15) W/Hz(1/2), and 8 GHz, respectively. All the parameters are comparable to those of similar devices made on InP substrate or other InGaAs products epitaxially grown on an InGaAlAs buffered GaAs substrate. The performances of the MM-PINPD on GaAs are analyzed by impulse injecting of 1.2-ps pulse-train, eye pattern at 10Gbps, and frequency response from VNA.
A conceptual framework of bank credit granting system-computer applications in Taiwan
(1995)
Kuo, HC
;
Wu, SS
;
Tarng, MY
;
交大名義發表
;
管理科學系
A novel method to improve VCSELs oxide-confined aperture uniformity using selective As+-implanted underlying layer
(2006-05-10)
Huang, HW
;
Kao, CC
;
Chang, YA
;
Kuo, HC
;
Laih, LH
We report the utilization of an selective As+-implanted underlying layer and regrowth method to enhance and control the wet thermal oxidation rate for 850 nm oxide-confined VCSEL. The oxidation rate of the As'-implanted device showed a four-fold increase over the non-implanted one at the As' dosage of 1 x 10(16) cm(-1) and the oxidation temperature of 400 degrees C. The 50 side-by-side As'-implanted oxide-confined VCSELs fabricated using the method achieved very uniform performance with a deviation in threshold current Of Delta I-th similar to 0.2 mA and slope-efficiency of Delta S.E. similar to 3%. Finally, we accumulated life test data for oxide-confined VCSELs with As'-implanted underlying layer up to 1000 h at 80 degrees C/15 mA. (c) 2005 Elsevier B.V. All rights reserved.
AlGaInP light-emitting diodes with stripe patterned omni-directional reflector
(2006-02-01)
Lee, YJ
;
Lu, TC
;
Kuo, HC
;
Wang, SC
;
Liou, MJ
An n-side-up AlGaInP-based light-emitting diode (LED) with a stripe-patterned omni-directional reflector (ODR) was fabricated by adopting the adhesive-layer bonding scheme. Comparing to the conventional ODR LED, the stripe-patterned ODR LED significantly enhanced the output power with an only slight higher forward voltage. This improvement was analyzed by the scanning near-field optical microscope (SNOM) and could be attributable to the geometrical shape of stripe patterns that redirects the guided light towards to the escaping cone of the LED surface. The optimized dimension of stripe patterns was also calculated by simply modeling a LED dice with a stripe-patterned ODR structure, according to optical ray-tracing method.
Aluminum incorporation into AlGaN grown by low-pressure metal organic vapor phase epitaxy
(2006-05-15)
Huang, GS
;
Yao, HH
;
Lu, TC
;
Kuo, HC
;
Wang, SC
Aluminum (Al) incorporation in AlxGa1-xN films grown by low-pressure metal organic vapor phase epitaxy using trimethylaluminum (TMAl) and trimethylgallium as group III precursors has been systematically studied. The solid phase Al composition of the AlxGa1-xN films varied nonlinearly with the Al gas phase composition. The incorporation kinetics of AlxGa1-xN alloy has been analyzed by using an adsorption-trapping model. Two parameters were used to characterize the properties of Al incorporation, i.e., the capture radius and the adsorption time of Al atoms. An exponential function of the Al composition of the AlxGa1-xN films versus the TMAl gas flow rate was obtained. It was demonstrated that the adsorption time of the Al atom was larger than the growth time of one atomic layer. The effects of ammonia flow rate, crystal growth rate, and growth temperature on the adsorption parameters were also discussed. (c) 2006 American Institute of Physics.
An optically pumped blue GaN-based vertical-cavity surface emitting laser employing AIN/GaN and Ta2O5/NO2 distributed bragg reflectors
(2005)
Kao, CC
;
Yao, HH
;
Peng, YC
;
Lu, TC
;
Kuo, HC
The laser action of GaN-based VCSEL with 3-lambda cavity and hybrid DBR mirrors, consisting of AlN/GaN and Ta2O5/SiO2 DBR was achieved under the optical pumping at room temperature. The laser emits 448nm blue wavelength with a linewidth of 0.25nm above threshold.
As+-implanted AlGaAs oxide-confined VCSEL with enhanced oxidation rate and high performance uniformity
(2004-06-01)
Laih, LH
;
Kuo, HC
;
Lin, GR
;
Laih, LW
;
Wang, SC
We report the utilization of an As+-implanted Al-GaAs region and regrowth method to enhance and control the wet thermal oxidation rate for 850-nm oxide-confined vertical-cavity surface-emitting laser (VCSEL). The oxidation rate of the As+-implanted device showed a four-fold increase over the nonimplanted one at the As+ dosage of 1 x 10(16) cm(-3) and the oxidation temperature of 400 degreesC. 50 side-by-side As+-implanted oxide-confined VCSELs fabricated using the method achieved very uniform performance with a deviation in threshold current of DeltaI(th) similar to 0.2 mA and slope-efficiency of DeltaS.E. similar to 3%.
Catalyst-free GaN nanorods grown by metalorganic molecular beam epitaxy
(2006-05-01)
Kuo, SY
;
Kei, CC
;
Hsiao, CN
;
Chao, CK
;
Lai, FI
High-density GaN nanorods with outstanding crystal quality were grown on c-sapphire substrates by radio-frequency plasma-assisted metalorganic molecular beam epitaxy under catalyst- and template-free growth condition. Morphological and structural characterization of the GaN nanorods was employed by X-ray diffraction, energy dispersive X-ray spectroscopy, scanning electron microscopy, and high-resolution transmission electron microscopy (HRTEM). These results indicate that the rod number density can reach 1 x 10(10) cm(-2) and the nanorods are well-aligned with preferentially oriented in the c-axis direction. Meanwhile, no metallic (Ga) droplet was observed at the end of the rods, which is the intrinsic feature of vapor-liquid-solid method. Nanorods with no traces of any extended defects, as confirmed by TEM, were obtained as well. In addition, optical investigation was carried out by temperature- and power-dependent micro-photoluminescence (mu-PL). The PL peak energies are red-shifted with increasing excitation power, which is attributed to many-body effects of free carriers under high excitation intensity. The growth mechanism is discussed on the basis of the experimental results. Catalyst-free GaN nanorods presented here might have a high potential for applications in nanoscale photonic devices.
Characteristics of stable emission GaN-based resonant-cavity light-emitting diodes
(2004-01-19)
Lin, CF
;
Yao, HH
;
Lu, JW
;
Hsieh, YL
;
Kuo, HC
The resonant-cavity light-emitting diode (RC-LED) structure was grown by MOCVD. The structure of RC-LED consisted of a 3lambda InGaN/GaN MQW LED cavity between the top TiO2/SiO2 DBR (81.7%, reflectance) and the bottom AlN/GaN DBR (90.4%) stack. A stable 410 nm emission peak and a low thermally induced red-shift effect (0.12 nm/kA/cm(2)) were measured by varying the injection current density. The light output power of the full RC-LED device was three times higher than the RC-LED without top TiO2/SiO2 DBR layers under 600 A/cm(2) inject current density. The narrow line width of 7.4 nm, emission peak localization at 410 nm, and three times higher output power were caused by the resonance effect in this vertical cavity structure. (C) 2003 Published by Elsevier B.V.
Characterization of InGaN/GaN multiple quantum well nanorods fabricated by plasma etching with self-assembled nickel metal nanomasks
(2005-04-01)
Hsueh, TH
;
Huang, HW
;
Kao, CC
;
Chang, YH
;
Ou-Yang, MC
High-density (3.0 x 1010 cm (-2)) InGaN/GaN Multiple quantum well (MQW) nanorods were fabricated from an as-grown bulk light-emitting diode structure by inductively coupled plasma dry etching with self-assembled nickel metal nanomasks. The self-assembled nickel metal nanomasks were formed by rapid thermal annealing of a nickel metal film at 850 degrees C for 1 min. The influence of the thicknesses of the Ni metal film on the dimensions and density of the nanorods was also investigated. The structural and optical properties of the InGaN/GaN MQW nanorods were established using field emission scanning electron microscopy, transmission electron microscopy and photoluminescence measurements. The diameters and heights of nanorods were estimated to be 60 to 100nm and more than 0.28 mu m, respectively. The peak emission wavelength of the nanorods showed a blue shift of 5.1 nm from that of the as-grown bulk. An enhancement by a factor of 5 in photoluminescence intensity of the nanorods compared with that of the as-grown bulk was observed. The blue shift is attributed to strain relaxation in the wells after dry etching, the quantum confinement effect, or a combination of the two, which results in the enhancement of emission intensity.
CO2 laser annealing synthesis of silicon nanocrystals buried in Si-rich SiO2
(2005)
Lin, CJ
;
Chueh, YL
;
Chou, LJ
;
Kuo, HC
;
Lin, GR
Localized synthesis of 3-8 nm Si nanocrystals (nc-Si) in PECVD-grown Si-rich SiO2 (SRSO) film is demonstrated using CO2 laser annealing at an intensity below the ablation-threshold (6.0 kW/cm(2)). At an optimized surface temperature of 1285 degrees C, the precipitated nc-Si in CO2-laser-annealed SRSO film results in near-infrared photoluminescence (PL) at 806 ran, whereas the ablation damage induced at higher laser intensities as well as temperatures results in blue PL at 410 nm related to structural defects. The refractive index of the laser-annealed SRSO at 633 nm increases from 1.57 to 2.31 as the laser intensity increases from 1.5 to 6.0 kW/cm(2). Transmission electron microscopy analysis reveals that the average size and volume density of Si nanocrystals embedded in the SRSO film are about 6 nm and 4.5 x 10(16) cm(-3), respectively. The CO2 laser annealing with controlled intensity and spot size can potentially accomplish in-situ, localized annealing of the SRSO film without causing irreversible damage to nearby electronics.
Comparisons of InP/InGaAlAs and InAlAs/InGaAlAs distributed Bragg reflectors grown by metalorganic chemical vapor deposition
(2004-02-25)
Lu, TC
;
Tsai, JY
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Kuo, HC
;
Wang, SC
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光電工程學系
Long wavelength vertical cavity surface emitting lasers (VCSELs) are considered the best candidates for the low cost reliable light emitters in fiber communications. The low refractive index contrast in the conventional InP-based lattice-matched distributed Bragg reflectors (DBRs), InP/InGaAsP, impeded the development of 1.3-1.5 mum VCSELs. However, the monolithic InP-based lattice-matched DBRs are still most attractive and desirable. The InP/InGaAlAs and InAlAs/InGaAlAs DBRs with larger refractive index contrast than the conventional InP/InGaAsP DBRs have been demonstrated recently. In this report, we compare these two material systems in terms of optical and electrical properties of DBRs. We found the InP/InGaAlAs DBRs have better electrical and optical properties, while the InAlAs/InGaAlAs DBRs have much lower growth complexity. (C) 2003 Elsevier B.V. All rights reserved.
Correlation between surface charge accumulation and excitation intensity dependent red-shifted micro-photoluminescence of Si-implanted quartz with embedded Si nanocrystals
(2004)
Lin, CJ
;
Yu, KC
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Kuo, HC
;
Ou-Yang, MJ
;
Lin, GR
The excitation intensity dependency of nanocrystallite Si (nc-Si) related micro-photoluminescence (mu-PL) from the multi-recipe Si-implanted quartz is characterized. The mu-PL at 724 nm contributed by nc-Si with 3-4 nm diameter is maximized after annealing at 1100degreesC for 3 hours. By increasing the excitation intensity from 10 kW/cm(2) to 300 kW/cm(2), the mu-PLs of 1-hr and 3-hr annealed quartz significantly red-shift from 723 nm to 725 nm and from 724 nm to 735 nm, respectively. This can be explained by the anomalous quantum stark effect due to a surface electric field oriented from photo-ionized nc-Si dots to quartz surface. After 1-hr illumination at power of 300 kW/cm(2), the mu-PL peak wavelength of 3-hr annealed sample is further red-shifted by 2.5 nm. By measuring the accumulated surface charges built up during optical excitation process, the correlation between excitation -intensity dependent PL wavelength red-shift and the photo-ionized nc-Si surface electric-field related quantum stark effect is primarily elucidated.
Crack-free GaN/AlN distributed Bragg reflectors incorporated with GaN/AlN superlattices grown by metalorganic chemical vapor deposition
(2006-02-06)
Huang, GS
;
Lu, TC
;
Yao, HH
;
Kuo, HC
;
Wang, SC
A crack-free GaN/AlN distributed Bragg reflector (DBR) incorporated with GaN/AlN superlattice (SL) layers was grown on a c-plane sapphire substrate by metalorganic chemical vapor deposition. Three sets of half-wave layers consisting of 5.5 periods of GaN/AlN SL layers and GaN layer were inserted in every five pairs of the 20 pair GaN/AlN DBR structure to suppress the crack generation. The grown GaN/AlN DBRs with SL insertion layers showed no observable cracks in the structure and achieved high peak reflectivity of 97% at 399 nm with a stop band width of 14 nm. Based on the x-ray analysis, the reduction in the in-plane tensile stress in the DBR structure with insertion of SL layers could be responsible for the suppression of crack formation and achievement of high reflectivity. (c) 2006 American Institute of Physics.
Dynamic characteristics of long-wavelength quantum dot vertical-cavity surface-emitting lasers with light injection
(2006-04-03)
Peng, PC
;
Kuo, HC
;
Tsai, WK
;
Chang, YH
;
Lin, CT
This investigation experimentally demonstrates the dynamic characteristics of quantum dot vertical-cavity surface-emitting lasers (QD VCSEL) without and with light injection. The QD VCSEL is fully doped structure on GaAs substrate and operates in the 1.3 mu m optical communication wavelength. The eye diagram, frequency response, and intermodulation distortion are presented. We also demonstrate that the frequency response enhancement by light injection technique allows us to improve the performance of subcarrier multiplexed system. (c) 2006 Optical Society of America.
Effect of annealing on low-threshold-current large-wavelength InGaAs quantum well vertical-cavity laser
(2006-02-01)
Chen, IL
;
Hsu, WC
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Kuo, HC
;
Sung, CP
;
Chiou, CH
An emission wavelength record emission wavelength of 1245 nm in double InGaAs/GaAs quantum wells without a strain-compensated barrier is obtained by metalorganic chemical vapor deposition (MOCVD). The effect of annealing on highly strained InGaAs quantum wells is analyzed using phtoluminanescence spectra. By comparing devices p-type distributed Bragg reflector (p-DBR) growth temperatures, the preliminary results indicate that a device with a low p-DBR growth temperature of 670 degrees C exhibits a low threshold current and a high light output power. A threshold current of 6.7 mA in an InGaAs vertical-cavity surface emitting laser (VCSEL) in CW operation is realized with an emission spectrum up to 1.26 mu m.