Browsing by Author "Chu, JT"

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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.
Effect of different n-electrode patterns on optical characteristics of large-area p-side down InGaN light-emitting diodes fabricated by laser lift-off
(2005)
Chu, JT
;
Liang, WD
;
Kao, CC
;
Huang, HW
;
Chu, CF
Large-area (1000x1000 gm) p-side down InGaN light-emitting diodes (LEDs) have been fabricated by laser lift-off (LLO) technique. The p-side down LEDs with different geometric patterns of n-electrode were fabricated to investigate electrode pattern-dependent optical characteristics. Current crowding effect was first observed in in the p-side down InGaN LLO-LEDs. The LEDs with well designed n-electrode shows a uniform distribution of light-emitting pattern and higher out put power due to uniform current spreading and minimization of thermal effect. The output power saturation induced by current crowding in the LEDs with simplest geometric n-electrode was demonstrated. In absent of transparent contact layer for current spreading, the n-electrode pattern has remarkable influence on the current distribution and consequently the light output power of the large-area p-side down LEDs.
Effects of different n-electrode patterns on optical characteristics of large-area p-side-down InGaN light-emitting diodes fabricated by laser lift-off
(2005-11-01)
Chu, JT
;
Kao, CC
;
Huang, HW
;
Liang, WD
;
Chu, CF
Large-area p-side-down InGaN light-emitting diodes (LEDs) 1000 x 1000 mu m(2) in size have been fabricated by laser lift-off (LLO). The p-side-down LEDs with different geometric patterns of n-electrodes were fabricated to investigate electrode pattern-dependent optical characteristics. The current crowding effect was observed in the large-area p-side-down InGaN LLO-LEDs. A LED with a well-designed n-electrode pattern shows a uniform distribution of light emission and a higher output power due to uniform current spreading. The output power saturation induced by the current crowding effect was investigated. In the absence of a transparent contact layer for current spreading, the n-electrode pattern has a marked influence on the current distribution and the consequent light output power of the large-area p-side-down LEDs.
Enhanced light output in InGaN/GaN light emitting diodes with excimer laser etching surfaces
(2006-04-01)
Huang, HW
;
Chu, JT
;
Kao, CC
;
Hsueh, TH
;
Lu, TC
The InGaN/GaN light-emitting diode (LED) with a top p-GaN surface nanoroughened using Ni nanomasks and laser etching has been fabricated. The light output power of the InGaN/GaN LED with a nanoroughened top p-GaN surface is 1.55-fold that of a conventional LED. The series resistance of InGaN/GaN LED was reduced by 32% due to the increase in the contact area of the nanoroughened surface.
Enhanced light output of an InGaN/GaN light emitting diode with a nano-roughened p-GaN surface
(2005-09-01)
Huang, HW
;
Chu, JT
;
Kao, CC
;
Hseuh, TH
;
Lu, TC
This investigation describes the development of an InGaN/GaN light emitting diode (LED) with a nano-roughened top p-GaN surface using an Ni nano-mask and laser etching. The light output of the InGaN/GaN LED with a nano-roughened top p-GaN surface is 1.55 times that of a conventional LED, and the wall-plug efficiency is 68% higher at 20 mA. The series resistance of the InGaN/GaN LED was reduced by 32% by the increase in the contact area of the nano-roughened surface.
Fabrication and characteristics of GaN-based microcavity light-emitting diodes with high reflectivity AIN/GaN distributed Bragg reflectors
(2006-04-01)
Peng, YC
;
Kao, CC
;
Huang, HW
;
Chu, JT
;
Lu, TC
In this paper, we report a GaN-based microcavity light-emitting diode (MCLED) which is composed of 25 pairs of high-reflectivity GaN/AlN distributed Bragg reflector (DBR) and 6 pairs of ex-situ deposited SiO2/TiO2 dielectric mirrors. The electroluminescence peak of this structure matched well with the high reflectance area of the top and bottom DBRs, and shows a narrow emission of approximately 6.7 nm. The fabricated device also shows a more excellent performance on the stability of the emission peak wavelength while varying injection current density and operating temperature than a regular LED.
Fabrication and performance of blue GaN-based vertical-cavity surface emitting laser employing AlN/GaN and Ta2O5/SiO2 distributed Bragg reflector
(2005-08-22)
Kao, CC
;
Peng, YC
;
Yao, HH
;
Tsai, JY
;
Chang, YH
GaN-based vertical-cavity surface emitting laser with 3 lambda cavity and hybrid mirrors, consisting of the 25 pairs AlN/GaN dielectric Bragg reflector and the 8 pairs Ta2O5/SiO2, was fabricated. The laser action was achieved under the optical pumping at room temperature with a threshold pumping energy density of about 53 mJ/cm(2). The laser emits 448 nm blue wavelength with a linewidth of 0.25 nm and the laser beam has a degree of polarization of about 84%. (c) 2005 American Institute of Physics.
Fabrication of GaN-based nanorod light emitting diodes using self-assemble nickel nano-mask and inductively coupled plasma reactive ion etching
(2004-10-25)
Huang, HW
;
Kao, CC
;
Hsueh, TH
;
Yu, CC
;
Lin, CF
We report a novel method to fabricate GaN-based nanorod light emitting diodes (LEDs) with controllable dimension and density using self-assemble nickel (Ni) and Ni/Si3N4 nano-masks and inductively coupled plasma reactive ion etching (ICP-RIE). Under the fixed Cl-2/Ar flow rate of 50/20 sccm. ICP/Bias power of 400/100 W and chamber pressure of 0.67 Pa, the GaN-based nanorod LEDs were fabricated with density of 2.2 x 10(9) to 3 x 10(10) cm(-2) and dimension of 150-60 nm by self assemble Ni nano-masks with various size. The size of Ni/Si3N4 nano-mask was control by the thickness Ni film ranging 150-50 Angstrom and rapid thermal annealing condition. The technique offers a controllable method of fabrication of GaN-based nanorod LEDs and should be applicable for fabrication of the others III-V nanoscale photonic and electronic devices. (C) 2004 Elsevier B.V. All rights reserved.
Fabrication of large-area GaN-based light-emitting diodes on Cu substrate
(2005-04-01)
Chu, JT
;
Huang, HW
;
Kao, CC
;
Liang, WD
;
Lai, FI
A large-area GaN-based light-emitting diode (LED) 1000 x 1000 mu m(2) in size with a p-side down configuration was fabricated using wafer bonding and laser lift-off (LLO) techniques. The thin GaN LED was transferred onto a copper substrate without p peeling or cracks. The large-area LEDs showed a uniform light-emission pattern over entire defined mesa area without a transparent contact layer on the p-type GaN. The operating current of the large-area LEDs can be driven up to 1000 mA with continuously increasing light output-power. The light output-power is 240 mW with a driving current of 1000 mA. Large-area emission and high current operation make the LLO-LEDs applicable to high-power LED applications.
Fabrication of p-side down GaN vertical ligbt emitting diodes on copper substrates by laser lift-off
(2004)
Chu, JT
;
Kuo, HC
;
Kao, CC
;
Huang, HW
;
Chu, CF
The fabrication process and performance characteristics of the laser lift-off (LLO) GaN light emitting diodes (LEDs) were investigated. The LLO-GaN LEDs with 300 x 300 mum(2) on Cu show a nearly 4-fold increase in the light output power over the regular LLO-LEDs on the sapphire substrate. High operation current for the LLO-LEDs on Cu was also demonstrated. The large area-emission of 1000 x 1000 Pm 2 of p-side down GaN LLO-LEDs on Cu were fabricated. Further improvement of max light output are achieved. The LLO process should be applicable to other GaN-based light emitting devices in particular for those high light output power and high operation current devices. (C) 2004 WILEY-VCH Verlag GmbH & Co, KGaA, Weinheim.
InGaN-based light-emitting diode with undercut side wall
(2004)
Kao, CC
;
Chu, JT
;
Huang, HW
;
Peng, YC
;
Yu, CC
InP/InGaAlAs distributed Bragg reflectors grown by low-pressure metal organic chemical vapor deposition
(2003-04-01)
Lu, TC
;
Tsai, JY
;
Chu, JT
;
Chang, YS
;
Wang, SC
Long-wavelength vertical cavity surface emitting lasers (VCSELs) are considered the best candidate for the future low-cost reliable light sources in fiber communications. However, the absence of high refractive index contrast in InP-lattice-matched materials impeded the development of 1.3-1.5 mum VCSELs. Although wafer fusions provided the alternative approaches to integrate the InP-based gain materials with the GaAs/AlAs materials for their inherent high refractive index contrast, the monolithic InP-based lattice-matched distributed Bragg reflectors (DBRs) are still highly attractive and desirable. In this report, we demonstrate InP/InGaAlAs DBRs with. larger refractive index contrast than InP/InGaAsP and InAlAs/InGaAlAs DBRs. The switching between InP and InGaAlAs layers and growth rate control have been done by careful growth interruption technique and accurate in situ optical monitoring in low-pressure metal organic chemical vapor deposition. A 35 pairs 1.55 mum centered InP/InGaAlAs DBRs has the stopband of more than 100 nut and the highest reflectivity of more than 99%. A VCSEL structure incorporating 3 5 pairs InP/InGaAlAs DBR as the bottom mirror combined with a 2lambda thick periodic gain cavity and 10 pairs SiO2/TiO2 top dielectric mirrors was fabricated. The VCSELs lased at 1.56 mum by optical pumping at room temperature with the threshold pumping power of 30 mW. (C) 2002 Elsevier Science B.V. All rights reserved.
Investigation of GaN LED with Be-implanted Mg-doped GaN layer
(2004-10-15)
Huang, HW
;
Kao, CC
;
Chu, JT
;
Kuo, HC
;
Wang, SC
We report the electrical and optical characteristics of GaN light emitting diode (LED) with beryllium (Be) implanted Mg-doped GaN layer. The p-type layer of Be-implanted GaN LED showed a higher hole carrier concentration of 2.3 x 10(18)CM(-3) and low specific contact resistance value of 2.0 x 10(-4) Omegacm(2) than as-grown p-GaN LED samples without Be-implantation. The Be-implanted GaN LEDs with InGaN/GaN MQW show slightly lower light output (about 10%) than the as-grown GaN LEDs, caused by the high RTA temperature annealing process. (C) 2004 Elsevier B.V. All rights reserved.
Large emitting area GaN based light emitting diode fabricated on conducting copper substrates
(2004)
Chu, JT
;
Liang, WD
;
Chu, CF
;
Kuo, HC
;
Wang, SC
Light-output enhancement in a nitride-based light-emitting diode with 22 degrees undercut sidewalls
(2005-01-01)
Kao, CC
;
Kuo, HC
;
Huang, HW
;
Chu, JT
;
Peng, YC
We successfully fabricated nitride-based light-emitting diodes (LEDs) with similar to 22degrees undercut sidewalls. The similar to 22degrees etching undercut sidewalls were achieved by controllable inductively coupled plasma reactive ion etching. With a 20-mA current injection, the output powers of the LED with similar to 22degrees undercut sidewalls and standard LED were 5.1 and 3 mW, respectively-a factor of 1.7 times enhancement. It was found that such undercut sidewalls could enhance the probability of escaping the photons outside from the LED in the near horizontal and in-plane directions. This simple and controllable method is beneficial to fabricate brighter LEDs.
MOCVD growth of highly strained 1.3 mu m InGaAs : Sb/GaAs vertical cavity surface emitting laser
(2006-01-25)
Chang, YA
;
Chu, JT
;
Ko, CT
;
Kuo, HC
;
Lin, CF
In0.45Ga0.55As:Sb/GaAs (1.3 mu m) vertical cavity surface emitting lasers (VCSELs) were grown by metalorganic chemical vapor deposition (MOCVD). A In0.45Ga0.55As:Sb/GaAs quantum well (QW) exhibited an emission wavelength of 1.26 mu m with narrow fullwidth at half-maximum (FWHM) of 35.9meV. For the fabricated VCSEL with 5 mu m diameter oxide-confined aperture, a room-temperature (RT).threshold current of 2.1 mA and an output power of 0.9 mW with 1.3 mu m emission were obtained. The 3 dB modulation frequency was measured to be 7.6 GHz. (c) 2005 Elsevier B.V. All rights reserved.
Nitride-based LEDs with nano-scale textured sidewalls using natural lithography
(2006-06-28)
Huang, HW
;
Kuo, HC
;
Chu, JT
;
Lai, CF
;
Kao, CC
This investigation describes the development of a InGaN/GaN light-emitting diode (LED) with textured sidewalls using natural lithography with polystyrene spheres (PSs) as the etching mask and dry etching the epitaxial layers of LEDs to achieve nano-scale textured sidewalls. The LED with textured sidewalls increased the output power of the InGaN - GaN multiple quantum well (MQW) LEDs by a factor of 1.3, indicating that the LED with nano-scale textured sidewalls had larger light extraction efficiency. The wall-plug efficiency of nitride-based LEDs was increased by 30% using textured sidewalls.
Optically pumped GaN-based vertical cavity surface emitting laser at room temperature
(2005)
Chu, JT
;
Liang, WD
;
Kao, CC
;
Huang, HW
;
Lu, TC
The optically pumped lasing action at 414 nm was obtained from a GaN-based VCSEL with an InGaN multiple quantum wells and two dielectric DBRs fabricated by laser lift-off. The threshold pumping energy is 270 nJ at room temperature conditions.
Room-temperature operation of optically pumped blue-violet GaN-based vertical-cavity surface-emitting lasers fabricated by laser lift-off
(2006-04-01)
Chu, JT
;
Lu, TC
;
Yao, HH
;
Kao, CC
;
Liang, WD
Room-temperature optically pumped GaN-based vertical-cavity surface- emitting lasers (VCSELs) were demonstrated by laser lift-off. A VCSEL was fabricated by combining a GaN-based cavity with two dielectric distributed Bragg reflectors: SiO2/TiO2 and SiO2/Ta2O5. The Q factor of the VCSEL is 518 indicating a good interfacial layer quality of the structure. The laser emits blue-violet wavelength light at 414 nm under optical pumping at room temperature with a threshold pumping energy of 270 nJ. The laser emission has a narrow linewidth of 0.25 nm and a degree of polarization of 70%. The laser emission patterns clearly indicate a vertical lasing action of the VCSEL.
Single mode 1.27-mu m InGaAS : Sb-GaAs-GaAsP quantum well vertical cavity surface emitting lasers
(2005-01-01)
Kuo, HC
;
Chang, YA
;
Chang, YH
;
Chu, JT
;
Tsai, MY
1.27 mu m InGaAs:Sb-GaAs-GaAsP vertical cavity surface emitting lasers (VCSELs) were grown by metalorganic 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 raised from room temperature to 70 degrees C. With a bias current of only 5mA, the 3dB modulation frequency response was measured to be 8.36 GHz, which is appropriate for 10 Gb/s operation. The maximal bandwidth is measured to be 10.7 GHz with modulation current efficiency factor (MCEF) of similar to 5.25 GHz/(mA)(1/2). These VCSELs also demonstrate high-speed modulation up to 10 Gb/s from 25 degrees C to 70 degrees C.