Browsing by Author "Hsueh, TH"

Now showing 1 - 16 of 16

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).
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.
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.
Enhancement in light output of InGaN-based microhole array light-emitting diodes
(2005-06-01)
Hsueh, TH
;
Shen, JK
;
Huang, HW
;
Chu, JY
;
Kao, CC
InGaN-based microhole array light-emitting diodes (LEDs) with hole diameters (d) of 3-15 mu m were fabricated using self-aligned etching. The effects of size on the device characteristics, including current density-voltage and light output-current density, were measured and compared with those of conventional broad-area (BA) LEDs fabricated from the same wafer. The electrical characteristics of the devices are similar to those of conventional BA LEDs. The light output from the microhole array LEDs increases with d up to 7 pm. However, the light output declined as d increased further, perhaps because of the combination of the enhancement in extraction efficiency caused by the large surface areas provided by the sidewalls and the decrease in area of light generation by holes in the microhole array LEDs. The ray tracing method was used with a two-dimensional model in TracePro software. The findings indicate that an optimal design can improve the light output efficiently of the microhole array LEDs.
Fabrication and characterization of In(0.25)Ga(0.75)N/GaN multiple quantum wells embedded in nanorods
(2005-10-01)
Hsueh, TH
;
Sheu, JK
;
Huang, HW
;
Chang, YH
;
Ou-Yang, MC
ln(0.25)Ga(0.75)N/GaN multiple quantum wells embedded in nanorods with diameters of 60-100nm were fabricated by inductively coupled plasma reactive ion etching with Cl(2)/Ar plasma. The strong optical emission of the nanorods, observed by micro-photoluminescence measurement at 80 K, reveals a large blue shift of about 90meV and an increase in photoluminescence intensity density of more than 17-fold, compared with that of the as-grown wafer under the same excitation power density of 80W/cm(2). These nanostructures have a high potential for application in efficient GaN-based vertical cavity emitters.
Fabrication and characterization of In0.25Ga0.75N/GaN multiple quantum wells embedded in nanorods
(2005-10-01)
Hsueh, TH
;
Sheu, JK
;
Huang, HW
;
Chang, YH
;
Ou-Yang, MC
ln(0.25)Ga(0.75)N/GaN multiple quantum wells embedded in nanorods with diameters of 60-100nm were fabricated by inductively coupled plasma reactive ion etching with Cl-2/Ar plasma. The strong optical emission of the nanorods, observed by micro-photoluminescence measurement at 80 K, reveals a large blue shift of about 90meV and an increase in photoluminescence intensity density of more than 17-fold, compared with that of the as-grown wafer under the same excitation power density of 80W/cm(2). These nanostructures have a high potential for application in efficient GaN-based vertical cavity emitters.
Fabrication and micro-photoluminescence investigation of Mg-doped gallium nitride nanorods
(2005-04-01)
Chang, YH
;
Hsueh, TH
;
Lai, FI
;
Chang, CW
;
Yu, CC
High-density magnesium (Mg)-doped gallium nitride (GaN) nanorods were fabricated by inductively coupled plasma reactive ion etching from a GaN film and had a mean length of approximately 50nm. A large blue-shift was observed in the photoluminescence (PL) peak energy of Mg-doped GaN nanorods under HeCd laser (325 nm) excitation. The PL spectra of the nanorods show a typical donor-acceptor-pair (DAP) emission at approximately 3.0 eV with a large blue-shift compared to that of the Mg-doped GaN film. The blue-shift energy increases from 8 meV to 67 meV as the excitation intensity varies from 12 kW/cm(2) to 56 kW/cm(2). Possible reasons for the power dependence of the spectral shift in the PL emission energy are discussed.
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 InGaN multi-quantum-well nanorod by Ni nano-mask
(2004)
Huang, HW
;
Hsueh, TH
;
Kao, CC
;
Chang, YH
;
Ou-Yang, M
Gallium nitride nanorods fabricated by inductively coupled plasma reactive ion etching
(2002-08-15)
Yu, CC
;
Chu, CF
;
Tsai, JY
;
Huang, HW
;
Hsueh, TH
We report a novel method of fabricating gallium nitride (GaN) nanotods of controllable dimension and density from GaN epitaxial film using inductively coupled plasma reactive ion etching (ICP-RIE). The GaN epitaxial film was grown on a sapphire substrate by metal-organic chemical vapor deposition. Under the fixed Cl-2/Ar flow rate of 10/25 sccm and ICP/bias power of 200/200 W. the GaN nanorods and array were fabricated with a density of 10(8)-10(10) cm(-2) and dimension of 20-100 nm by varying the chamber pressure from 10 to 30 mTorr. The technique offers one-step, controllable method for the fabrication of GaN nanostructures and should be applicable for the fabrication of GaN-based nano-optoelectronic devices.
High-speed characteristics of large-area single-transverse-mode vertical-cavity surface-emitting lasers
(2003-10-16)
Hsueh, TH
;
Kuo, HC
;
Lai, FI
;
Laih, LH
;
Wang, SC
The single transverse mode operation of VCSELs with low threshold current (I-th) of 1.5 mA, slope efficiencies about 0.35 W/A, high optical output power of 3.8 mW and speed performance of 10 Gbit/s is reported. The laser has continuous-wave operation and employs oxygen implantation, MOCVD regrowth and selective oxidation on semi-insulating GaAs substrate.
High-speed modulation of 850 nm InGaAsP/InGaP strain-compensated VCSELs
(2003-07-10)
Kuo, HC
;
Chang, YS
;
Lai, FY
;
Hsueh, TH
;
Laih, LH
High performance 850 um InGaAsP/InGaP strain-compensated vertical cavity surface emitting lasers (VCSELs) are demonstrated with superior output characteristics and modulation bandwidths up to 12.5 Gbit/s from 25 to 85degreesC.
Improvement of kink characteristics performance of GaAsVCSEL with a indium-tin-oxide top transparent overcoating
(2004-11-15)
Lai, F
;
Chang, YH
;
Hsueh, TH
;
Huang, HW
;
Laih, LH
We demonstrated the enhancement in the performance of proton-implanted GaAs VCSEL by incorporation of a new p-contact scheme using a Ti and ITO transparent overcoating on the regular p-contact. The kink characteristics in light output power versus current (L-I) curve of the VCSEL with the Ti/ITO overcoating were improved with a reduction in the derivative kink factor of as large as 70%. The high-speed response of the overcoated device also shows a more open clear eye and lower jitter of 35 ps operating at 2.125 Gb/s under 10 mA bias and 9 dB extinction ratio compared to the no overcoated device. Better current spreading and uniformity induced by the overcoating could be responsible for these performance improvements. (C) 2004 Elsevier B.V. All rights reserved.
Performance of 850 nm AlGaAs/GaAs implanted VCSELs utilizing silicon implantation induced disordering
(2003-10-01)
Lai, FI
;
Hsueh, TH
;
Chang, YH
;
Shu, WC
;
Lai, LH
In this paper, we report a novel implanted vertical surface emitting lasers (VCSELs) utilizing silicon implantation induced disordering. The VCSELs exhibit kink-free current-light Output performance with threshold currents similar to2.4 mA, and the slope efficiencies similar to0.45 W/A. The threshold current change with temperature is minimal and the slope efficiency drops less than similar to30% when the substrate temperature is raised to 90 degreesC. The eye diagram of VCSEL operating at 2.125 Gb/s with 7 mA bias and 10 dB extinction ratio shows very clean eye with jitter less than 30 ps. We have accumulated life test data up to 5000 It at 100 degreesC/20 mA with exceptional reliability and the WHTOL (high temperature and high humidity 85 degreesC/85 operating lifetime) biased at 8 mA has passed over 2000 h. (C) 2003 Elsevier Ltd. All rights reserved.
Photoluminescence from In0.3Ga0.7N/GaN multiple-quantum-well nanorods
(2005-04-01)
Hsueh, TH
;
Huang, HW
;
Lai, FI
;
Sheu, JK
;
Chang, YH
The fabrication of ln(0.3)Ga(0.7)N/GaN multiple-quantum-well nanorods with diameters of 60-100 nm and their optical characteristics performed by micro-photoluminescence measurements are presented. The nanorods were fabricated by inductively coupled plasma dry etching from a light-emitting diode wafer. The structure and surface properties of fabricated nanorods were verified by the field emission scanning electron microscopy and the transmission electron microscopy. The photoluminescence (PL) spectra with sharp linewidths of typically 1.5 nm were observed at 4 K. The excitation-power-dependent spectra show that no energy shift was observed for these sharp peaks. Moreover, increasing the excitation power instead leads to an occurrence of new, sharp PL peaks at the higher energy tail of the PL spectra, which suggest that excitons are strongly confined in quantum-dot-like regions or localization centres.
Thermal annealing effects on the optical gain of InGaN/GaN quantum well structures
(2003-03-01)
Chen, CC
;
Hsueh, TH
;
Ting, YS
;
Chi, GC
;
Chang, CA
In this work, the variation of the optical gain in the InGaN/GaN quantum well after thermal annealing is simulated. The potential profile change of the quantum well resulting from the interdiffusion of Ga and In atoms across the interface of the well and the barrier during the thermal treatments is assumed to follow Fick's law. The results show that the thermal annealing can induce an increase of the optical gain in the InGaN/GaN quantum well. The maximum optical gain can be obtained at a diffusion length of 0.4 nm of In and Ga atoms. However, an excessive annealing may result in decreasing the optical gain. There is a good agreement between the experimental data in literature and the optimized diffusion length studied in this work. (C) 2002 Elsevier Science Ltd. All rights reserved.