Browsing by Author "Laih, LH"

Now showing 1 - 20 of 20

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).
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.
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%.
Characteristics of SiC-based thin-film LED fabricated using plasma-enhanced CVD system with stainless steel mesh
(1999-07-22)
Chen, YA
;
Hsu, ML
;
Laih, LH
;
Hong, JW
;
Chang, CY
A conventional plasma-enhanced chemical vapour deposition (PECVD) system with a stainless steel mesh attached to a cathode was used to fabricate an SiC-based thin-mm light-emitting diode (TFLED) at a low temperature (similar to 180 degrees C). The obtained TFLED had a brightness (B) of 1060cd/m(2) at an injection current density (J) of 600mA/cm(2) and a threshold voltage (V-th) of 12.6V, which were much better than those of 330cd/m(2) and 18.5V for an amorphous SiC-based TFLED fabricated by the same PECVD system without a stainless steel mesh.
Double graded-gap hydrogenated amorphous silicon carbide thin-film light-emitting diode with composition-graded N layer and carbon-increasing P layer
(1996-02-01)
Chen, YA
;
Chen, JK
;
Tsay, WC
;
Laih, LH
;
Hong, JW
An hydrogenated amorphous silicon carbide (a-SiC:H) p-i-n thin-film light-emitting diode (TFLED), in which a composition-graded n layer and carbon-increasing p layer respectively replace the constant optical-gap p-a-SiC:H layer and n-a-SiC:H layer employed in the previously reported double graded-gap (DG) TFLED and which contains dopant-graded p-i and i-n junctions, was successfully fabricated tu improve the electroluminescence (EL) of TFLED. This device had a brightness of 400 cd/m(2) at an injection current density of 600 mA/cm(2) and its EL threshold voltage (V-th) was only 9.0 V. The device EL spectrum showed a peak at 586 nm wavelength and emitted yellowish-orange light. The proposed TFLED had good stability of EL intensity and the EL spectrum during normal operation. The optimum conditions of rapid thermal annealing (RTA), which improved the ohmic contact between the amorphous layer and external electrode of the device, were 5 min at 300 degrees C in a 250 Torr H-2 ambient.
Electrical and luminescent characteristics of alpha-SiC:H p-i-n thin-film LED's with graded-gap junctions
(1997-04-01)
Jen, TS
;
Shin, NF
;
Laih, LH
;
Chen, YA
;
Hong, JW
A-SiC:H p-i-n thin-film LED's (TFLED's) containing a single graded-gap p-i-n junction (SG) or double graded-gap p-i-n and i-n junctions (DG) have been postulated and fabricated successfully on indium-tin-oxide (ITO)-coated glass substrates, with a plasma-enhanced chemical vapor deposition (PECVD) system, Some important characteristics and related physics of these two types of TFLED's are presented and discussed, At an injection current density (J) of 600 mA/cm(2), the brightness (B) of the SG and DG TFLED's obtained were 30 and 207 cd/m(2), respectively, This significant improvement of brightness, as compared to those of the previously reported TFLED's with a highest brightness of 20 cd/m(2), could be ascribed to the reduced interface states with the graded-gap junctions, lower contact resistance between ITO and p-layer due to a plasma treatment of ITO prior to p-layer deposition, post metallization annealing of thermally evaporated Al on n-layer, and higher optical gaps (E(opt)'s) of the doped layers employed, The slopes of the nearly linear B-J relationships show the diode factor very close to unity for the fabricated SG and DG TFLED's, This implies that the electroluminescence (EL) mechanism of these TFLED's might be a tail-to-tail-state recombination, In addition, the conduction currents of these TFLED's are almost temperature dependent, and that of the DG TFLED might consist of an ohmic current and a space-charge-limited current (SCLC) within the lower and higher applied-bias regions, respectively.
Fabrication and characteristics of high-speed oxide-confined VCSELs using InGaAsP-InGaP strain-compensated MQWs
(2004-12-01)
Chang, YH
;
Kuo, HC
;
Lai, FI
;
Chang, YA
;
Lu, CY
This paper presents the fabrication and characteristics of high-performance 850-mn InGaAsP-InGaP strain-compensated multiple-quantum-well (MQW) vertical-cavity surface-emitting lasers (VCSELs). The InGaAsP-InGaP MQW's composition was optimized through theoretical calculations, and the growth condition was optimized using photoluminescence. These VCSELs exhibit superior performance with characteristics threshold currents similar to0.4 mA and slope efficiencies similar to0.6 mW/mA. The threshold current change with temperature is less than 0.2 mA, and the slope efficiency drops less than similar to30% when the substrate temperature is raised from room temperature to 85degreesC. A high modulation bandwidth of 14.5 GHz and a modulation current efficiency factor of 11.6 GHz/(mA) (1/2) are demonstrated. The authors have accumulated life test data up to 1000 h at 70degreesC/8 mA.
Fabrication of high speed and reliable 850nm oxide-confined VCSELs for 10Gb/s data communication
(2005)
Kuo, HC
;
Chang, YH
;
Chang, YA
;
Tseng, KF
;
Laih, LH
In this paper, we demonstrate high performance 850 nm InGaAsP/InGaP strain-compensated MQWs vertical-cavity surface-emitting lasers (VCSELs). These VCSELs exhibit superior performance with threshold currents of similar to 0.4 mA, and slope efficiencies of similar to 0.6 mW/mA. High modulation bandwidth of 14.5 GHz and modulation current efficiency factor of 11.6 GHz/(mA)(1/2) are demonstrated. We have accumulated life test data up to 1000 hours at 70 degrees C/8mA. In addition, we also report a high speed planarized 850nm oxide-implanted VCSELs process that does not require semiinsulating substrates, polyimide planarization process, or very small pad areas, therefore very promising in mass manufacture.
High speed performance of 850 nm silicon-implanted AlGaAs/GaAs vertical cavity emitting lasers
(2004-03-01)
Kuo, HC
;
Chang, YS
;
Lai, FY
;
Hseuh, TH
;
Chu, LT
In this paper, we report a high speed performance of silicon-implanted vertical surface emitting lasers (VCSELs) with the aperture size 6x6 mum(2). These VCSELs exhibit kink-free current-light output with threshold currents similar to1.14 mA, and the slope efficiencies similar to0.5 W/A. The eye diagram of VCSEL operating at 10 Gb/s with 6 mA bias and 6 dB extinction ratio shows very clean eye. The rise time is 29 ps and fall time is 41 ps with jitter (p-p) = 21 ps. We have accumulated life test data up to 1000 h at 70 degreesC/10 mA. (C) 2003 Elsevier Ltd. All rights reserved.
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 high speed performance for 10-Gb/s 850-nm VCSELs using InGaAsP/InGaP strain-compensated MQWs
(2004)
Chang, YS
;
Kuo, HC
;
Lai, FI
;
Chang, YA
;
Laih, LH
We present in this paper the MOCVD growth and characterization of high performance 850nm InGaAsP/InGaP strain-compensated MQWs vertical-cavity surface-emitting lasers (VCSELs). These VCSELs exhibit superior characteristics, with threshold currents similar to0.4 mA, and slope efficiencies similar to 0.6 mW/mA. The threshold current change is less than 0.2 mA and the slope efficiency drops by less than similar to30% when the substrate temperature is raised from room temperature to 85degreesC. These VCSELs also demonstrate high speed modulation bandwidth up to 12.5Gbit/s from 25degreesC to 85degreesC.
Improvement of kink characteristic of proton implanted VCSEL with ITO overcoating
(2004)
Lai, FI
;
Chang, YH
;
Laih, LH
;
Kuo, HC
;
Wang, SC
Proton implanted VCSEL has been demonstrated with good reliability and decent modulation speed up to 1.25 Gb/s. However, kinks in current vs light output (L-I) has been always an issue in the gain-guided proton implant VCSEL. The kink related jitter and noise performance made it difficult to meet 2.5 Gb/s (OC-48) requirement. The kinks in L-I curve can be attributed to non-uniform carrier distribution induced non-uniform gain distribution within emission area. In this paper, the effects of a Ti/TO transparent over-coating on the proton-implanted AlGaAs/GaAs VCSELs (15um diameter aperture) are investigated. The kinks distribution in L-I characteristics from a 2 inch wafer is greatly improved compared to conventional process. These VCSELs exhibit nearly kink-free L-I output performance with threshold currents similar to3 mA, and the slope efficiencies similar to 0.25 W/A. The near-field emission patterns suggest the Ti/ITO over-coating facilitates the current spreading and uniform carrier distribution of the top VCSEL contact thus enhancing the laser performance. Finally, we performed high speed modulation measurement. The eye diagram of proton-implanted VCSELs with Ti/ITO transparent over-coating operating at 2.125 Gb/s with 10mA bias and 9dB extinction ratio shows very clean eye with jitter less than 35 ps.
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.
Optoelectronic characteristics of a-SiC : H-based pin thin film LEDs having a thin Mo buffer layer in contact with p-type a-Si : H
(1998-07-09)
Chen, YA
;
Wu, YH
;
Tsay, WC
;
Laih, LH
;
Hong, JW
To improve the electroluminescence (EL) properties of the nSiC:H-based pin thin film light-emitting diodes (TFLEDs) with the promotion of hole injection efficiency, a thin Mo metal film was used as a buffer layer to prevent reactions between the ITO (indium-tin-oxide) electrode and the p(+)-a-Si:H layer. With the formation of semi-transparent Mo silicide after annealing, a lower EL threshold voltage and a significantly higher brightness for a finished TFLED were achieved. The brightness of the obtained device was 1300cd/m(2) at an injection current density of 600mA/cm(2), and its EL threshold voltage was 14V.
Optoelectronic characteristics of alpha-SiC:H-based P-I-N thin-film light-emitting diodes with low-resistance and high-reflectance N+-alpha-SiCGe:H layer
(1997-09-01)
Chen, YA
;
Chiou, CF
;
Tsay, WC
;
Laih, LH
;
Hong, JW
The graded-gap a-SiC:II-based p-i-n thin-film light-emitting diodes (TFLED's) with an additional low-resistance and high-reflectance n(+)-a-SiCGe:H layer mere proposed and fabricated on indium-tin-oxide (ITO)-coated glass substrate in this paper. For a finished TFLED, a brightness of 720 cd/m(2) could be obtained at an injection current density of 600 mA/cm(2), and its EL (electroluminescence) threshold voltage was lowered to 8.6 V. in addition, the effects of reflectance and resistance of a-SiCGe:H film an the performance of TFLED were discussed, The optimum rapid thermal annealing (RTA) conditions for fabrication of TFLED after metallization were also studied and employed to improve the optoelectronic characteristics of TFLED.
Optoelectronic characteristics of alpha-SiC:H-based P-I-N thin-film light-emitting diodes with low-resistance and high-reflectance N+-alpha-SiCGe:H layer
(1997-09-01)
Chen, YA
;
Chiou, CF
;
Tsay, WC
;
Laih, LH
;
Hong, JW
The graded-gap a-SiC:II-based p-i-n thin-film light-emitting diodes (TFLED's) with an additional low-resistance and high-reflectance n(+)-a-SiCGe:H layer mere proposed and fabricated on indium-tin-oxide (ITO)-coated glass substrate in this paper. For a finished TFLED, a brightness of 720 cd/m(2) could be obtained at an injection current density of 600 mA/cm(2), and its EL (electroluminescence) threshold voltage was lowered to 8.6 V. in addition, the effects of reflectance and resistance of a-SiCGe:H film an the performance of TFLED were discussed, The optimum rapid thermal annealing (RTA) conditions for fabrication of TFLED after metallization were also studied and employed to improve the optoelectronic characteristics of TFLED.
Porous silicon light-emitting diode with tunable color
(1997-05-01)
Chen, YA
;
Chen, BF
;
Tsay, WC
;
Laih, LH
;
Chang, MN
We successfully combined porous silicon and amorphous silicon together to fabricate a light-emitting diode, whose emitting color was tunable with different applied voltage. When the applied voltage increased from 30 to 90 V, the emitting color of the device could change from red to blue. (C) 1997 Elsevier Science Ltd.
Simulation and analysis of 1300-nm In0.4Ga0.6As0.986N0.014/GaAs1-xNx quantum-well lasers with various GaAs1-xNx strain compensated barriers
(2004)
Chang, YA
;
Kuo, HC
;
Chang, YH
;
Wang, SC
;
Laih, LH
In this article, the laser performance of the 1300-nm In0.4Ga0.6As0.986N0.014/GaAs1-xNx quantum well lasers with various GaAs1-xNx strain compensated barriers (x=0%, 0.5%, 1 %, and 2%) have been numerically investigated with a laser technology integrated simulation program. The simulation results suggest that with x=0% and 0.5% can have better optical gain properties and high characteristic temperature coefficient To values of 110 K and 94 K at the temperature range of 300-370 K. As the nitrogen composition in GaAs1-xNx barrier increases more than 1% the laser performance degrades rapidly and the To value decreases to 87 K at temperature range of 300-340 K. This can be attributed to the decrease of conduction band carrier confinement potential between In0.4Ga0.6As0.986N0.014 QW and GaAs1-xNx barrier and the increase of electronic leakage current. Finally, the temperature dependent electronic leakage current in the InGaAsN/GaAs1-xNx quantum-well lasers are also investigated.
Temperature dependent near-field emission profiles of oxide-confined vertical cavity surface emitting lasers
(2003)
Lu, TC
;
Shieu, WJ
;
Chang, YH
;
Laih, LH
;
Wang, SC
The near-field emission profiles of oxide confined GaAs vertical cavity surface emitting lasers (VCSELs) with 20 mum aperture have been investigated at different operating temperature and different driving current. The subthreshold emission profile provided the information of carrier distributions. At 20degreesC, a uniform plateau profile was observed at subthreshold emission, which then transferred to a fundamental mode at just above the threshold current. At higher driving current, the fundamental mode evolved into higher order modes due to the spatial hole burning effect. However, at 90degreesC the subthreshold emission was no longer a uniform plateau profile but showed some locally high gain regions off the aperture center. The subsequent lasing mode profiles showed high order mode in coincidence with these locally high gain regions at 90degreesC. The higher order mode profiles remained nearly unchanged under different temperature conditions when driving at constant current above the threshold. These locally. high gain regions probably caused by the non-uniformity of the open aperture and the current crowding effect. In addition to the spatial hole burning and thermal lensing effect, these locally high gain regions appeared at elevated operation temperature also affected the higher order mode transitions of oxide-confined VCSELs.