Browsing by Author "Kuo, Chien-Cheng"

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Development of GaN-Based Vertical-Cavity Surface-Emitting Lasers
(2009-05-01)
Lu, Tien-Chang
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Chen, Jun-Rong
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Chen, Shih-Wei
;
Kuo, Hao-Chung
;
Kuo, Chien-Cheng
This paper reviews the fabrication technology and performance characteristics of optically pumped and electrically pumped GaN-based vertical-cavity surface-emitting lasers (VCSELs). The lasing action of optically pumped hybrid GaN-based VCSELs has been observed at room temperature due to the employment of high-quality and high-reflectivity AlN/GaN-based distributed Bragg reflectors in the VCSEL structure. Based on the device structure of the optically pumped hybrid GaN-based VCSELs, we further achieved the lasing action of electrically pumped GaN-based VCSELs under continuous-wave operation at 77 K. The laser has a threshold injection current of 1.4 mA and emits a blue wavelength at 462 nm together with a narrow linewidth of about 0.15 nm. The laser beam has a divergence angle of about 11.7 degrees with a polarization ratio of 80%. A very strong spontaneous coupling efficiency of 7.5 x 10(-2) was measured.
Large vacuum Rabi splitting in ZnO-based hybrid microcavities observed at room temperature
(2009-02-09)
Chen, Jun-Rong
;
Lu, Tien-Chang
;
Wu, Yung-Chi
;
Lin, Shiang-Chi
;
Liu, Wei-Rein
Wide-band gap ZnO semiconductors are attractive materials for the investigation of microcavity exciton polaritons due to the large exciton binding energy and oscillator strength. We report the growth and characterization of bulk ZnO-based hybrid microcavity. The phenomenon of strong exciton-photon coupling at room temperature has been observed in the ZnO-based hybrid microcavity structure, which consists of 30 pair epitaxially grown AlN/AlGaN distributed Bragg reflector (DBR) on the bottom side of the 3/2 lambda thick ZnO cavity and 9 pair SiO(2)/HfO(2) DBR as the top mirror. The cavity quality factor is about 221. The experimental results show good agreement with theoretically calculated exciton-polariton dispersion curves based on transfer matrix method. From the theoretical and experimental exciton-polariton dispersion curves with two different cavity-exciton detuning values, the large vacuum Rabi splitting is estimated to be about 58 meV in the ZnO-based hybrid microcavity.
Large Vacuum Rabi Splitting in ZnO-Based Microcavities
(2009)
Chen, Jun-Rong
;
Lu, Tien-Chang
;
Wu, Yung-Chi
;
Lin, Shiang-Chi
;
Liu, Wei-Rein
We report the growth and characterization of bulk ZnO-based hybrid microcavity (MC). The phenomenon of strong exciton-photon coupling at room temperature has been observed in the ZnO-based MC. The cavity quality factor is 221. The experimental results show good agreement with calculated exciton-polariton dispersion curves based on transfer matrix method. From the theoretical and experimental exciton-polariton dispersion curves with two different cavity-exciton detuning values, the large vacuum Rabi splitting is estimated to be 58 meV in the ZnO-based MC.
Microscopic evidence for the dissociation of water molecules on cleaved GaN(1(1)over bar00)
(2018-01-14)
Wu, Shih-Yu
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Lang, Liang-Wei
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Cai, Pei-Yang
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Chen, Yun-Wen
;
Lai, Yu-Ling
The dissociation of water molecules absorbed on a cleaved non-polar GaN(1(1)over bar00) surface was studied primarily with synchrotron-based photoemission spectra and density-functional-theory calculations. The adsorbed water molecules are spontaneously dissociated into hydrogen atoms and hydroxyl groups at either 300 or 130 K, which implies a negligible activation energy (<11 meV) for the dissociation. The produced H and OH were bound to the surface nitrogen and gallium on GaN(1(1)over bar00) respectively. These results highlight the promising applications of the non-polar GaN(1(1)over bar00) surface in water dissociation and hydrogen generation.
Observation of Polariton Dispersions for ZnO Microcavities in Strong Couple Regime
(2010)
Chen, Jun-Rong
;
Lu, Tien-Chang
;
Wu, Yung-Chi
;
Lin, Shiang-Chi
;
Liu, Wei-Rein
Characteristics of ZnO-based MCs with vacuum Rabi splitting of 72 meV are demonstrated. It is found that only the LPBs can be observed in ZnO MCs since the Rabi splitting pushes UPBs into scattering absorption.