Browsing by Author "Chen, Chien-Kang"

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Characteristics of Current-Injected GaN-Based Vertical-Cavity Surface-Emitting Lasers
(2011-11-01)
Lu, Tien-Chang
;
Wu, Tzeng-Tsong
;
Chen, Shih-Wei
;
Tu, Po-Min
;
Li, Zhen-Yu
This paper reviews the fabrication technology and performance characteristics of current-injected GaN-based vertical-cavity surface-emitting lasers (VCSELs) with hybrid distributed Bragg reflectors (DBRs). The GaN-based VCSEL consists of a ten-pair Ta(2)O(5)/SiO(2) top DBR, a 7 lambda-thick optical cavity embedded with 10 InGaN/GaN multiquantum wells, and a 29-pair AlN/GaN bottom DBR. Lasing action is observed under continuous-wave operation at room temperature. The laser characteristics, such as temperature-dependent laser threshold current, emission wavelength, and spontaneous emission coupling factors, have been measured and discussed.
Characteristics of GaN-based Vertical Cavity Surface Emitting Lasers with Hybrid Mirrors
(2011)
Lu, Tien-Chang
;
Cheng, Bo Siao
;
Wu, Tzeng-Tsong
;
Chen, Shih-Wei
;
Chen, Chien-Kang
We demonstrated CW current injection of GaN VCSELs with hybrid mirrors at room temperature. The laser characteristics, such as temperature dependent laser threshold current, spontaneous emission coupling factors, have been measured and discussed. (C)2011 Optical Society of America
Continuous wave operation of current injected GaN vertical cavity surface emitting lasers at room temperature
(2010-08-16)
Lu, Tien-Chang
;
Chen, Shih-Wei
;
Wu, Tzeng-Tsong
;
Tu, Po-Min
;
Chen, Chien-Kang
We report the demonstration of the continuous wave laser action on GaN-based vertical cavity surface emitting lasers at room temperature. The laser structure consists of a ten-pair Ta(2)O(5)/SiO(2) distributed Bragg reflector (DBR), a 7 lambda-thick optical cavity, ten-pairs InGaN/GaN multiquantum wells with an AlGaN electron blocking layer, and a 29-pair AlN/GaN DBR. The laser has a threshold current of about 9.7 mA corresponding to the current density of about 12.4 kA/cm(2) and a turn-on voltage about 4.3 V at 300 K. The lasing wavelength was 412 nm with a linewidth of about 0.5 nm. A spontaneous emission coupling efficiency factor of about 5x10(-3) and the degree of polarization of about 55% were measured, respectively. The laser beam has a narrow divergence angle of about 8 degrees. (C) 2010 American Institute of Physics. [doi:10.1063/1.3483133]
Enhanced Output Power of GaN-Based Resonance Cavity Light-Emitting Diodes With Optimized ITO Design
(2011-12-15)
Wu, Tzeng-Tsong
;
Lin, Chien-Chung
;
Wu, Yun-Lin
;
Chen, Chien-Kang
;
Lu, Tien-Chang
We fabricated and measured GaN-based resonant cavity light-emitting diodes with a 30 nm thick Indium tin oxide (ITO) thin film as a transparent contact layer. Four different ITO structures on p-type GaN samples were deposited by sputter and e-gun, and the corresponding device performance was compared. Each of these four samples has been annealed by its optimal parameters. The ITO thin film deposited by sputter demonstrated better electrical characteristics, surface morphology, specific contact resistance, and the overall device light output compared to those of the e-gun samples. Between the two sputtered ITO types, the hybrid type shows higher roll-over current density of 14 kA/cm(2), and the output power is increased from 15 to 39 mu W. From statistical data of the 2-D light intensity under the same current, we saw the lateral current spreading of the pure crystalline ITO by sputter is worst. The hybrid type, which combines the crystalline and amorphous ITO, has the best overall performance when we consider all the electrical, optical, and metrology measurements. From these results, we believe the 30 nm thick hybrid ITO thin film has the best potential to be applied in light emitting devices such as light-emitting diodes, laser diodes, etc.