Browsing by Author "Liu, S. C."

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AlGaInAs quantum-well 1.3-mu m laser by a diode-pumped actively Q-switched Nd : GdVO4 laser - art. no. 68712K
(2008)
Huang, S. C.
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Su, K. W.
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Li, A.
;
Liu, S. C.
;
Chen, Y. F.
We report a high-peak-power AlGaInAs 1.36-mu m vertical-external-cavity surface-emitting laser (VECSEL) optically pumped by a diode-pumped actively Q-switched Nd:GdVO4 1.06-mu m laser under room-temperature operation. The gain medium is an AlGaInAs quantum wells (QWs)/barrier structure grown on a Fe-doped InP substrate by metalorganic chemical-vapor deposition. With an average pump power of 1.9 W, an average output power of 340 mW was obtained at a pulse repetition rate of 40 kHz, corresponding to an optical-to-optical conversion efficiency of 18.76%. With a peak pump power of 7.9 kW, the highest peak output power was 1.3 kW at a pulse repetition rate of 10 kHz.
AlGaInAs quantum-well as a saturable absorber in a diode-pumped passively Q-switched solid-state laser
(2007-06-01)
Huang, S. C.
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Liu, S. C.
;
Li, A.
;
Su, K. W.
;
Chen, Y. F.
We demonstrate what is believed to be the first use of AlGaInAs quantum wells (QWs) as a saturable absorber in the Q switching of a high-power diode-pumped Nd-doped 1.06 mu m laser. The barrier layers are designed to locate the QW groups in the region of the nodes of the lasing standing wave to avoid damage. With an incident pump power of 13.5 W, an average output power of 3.5 W with a Q-switched pulse width of 0.9 ns at a pulse repetition rate of 110 kHz was obtained. (c) 2007 Optical Society of America.
AlGaInAs/InP eye-safe laser pumped by a Q-switched Nd:GdVO(4) laser
(2009-03-01)
Huang, S. C.
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Chang, H. L.
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Su, K. W.
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Li, A.
;
Liu, S. C.
An AlGaInAs quantum-well structure grown on a Fe-doped InP transparent substrate is developed to be a gain medium in a high-peak-power nanosecond laser at 1570 nm. Using an actively Q-witched 1064 nm laser to pump the gain chip, an average output power of 135 mW is generated at a pulse repetition rate of 30 kHz and an average pump power of 1.25 W. At a pulse repetition rate of 20 kHz, the peak output power is up to 290 W at a peak pump power of 2.3 kW.
AlGaInAs/InP eye-safe laser pumped by a Q-switched Nd:GdVO4 laser
(2009-03-01)
Huang, S. C.
;
Chang, H. L.
;
Su, K. W.
;
Li, A.
;
Liu, S. C.
An AlGaInAs quantum-well structure grown on a Fe-doped InP transparent substrate is developed to be a gain medium in a high-peak-power nanosecond laser at 1570 nm. Using an actively Q-witched 1064 nm laser to pump the gain chip, an average output power of 135 mW is generated at a pulse repetition rate of 30 kHz and an average pump power of 1.25 W. At a pulse repetition rate of 20 kHz, the peak output power is up to 290 W at a peak pump power of 2.3 kW.
Enhancement-Mode GaN MIS-HEMTs with HfLaOx Gate Insulator
(2016)
Lin, Y. C.
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Lin, J. C.
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Lin, Y.
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Wu, C. H.
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Huang, Y. X.
GaN MIS-HEMT with Low Dynamic ON-resistance Using SiON Passivation
(2016-01-01)
Liu, S. C.
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Huang, C. K.
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Chang, E. Y.
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材料科學與工程學系
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電子工程學系及電子研究所
An effective SiON passivation with high density of positive fixed charges for GaN MIS-HEMTs is demonstrated. The positive fixed charges at the SiON/AlGaN interface effectively reduce the surface potential and expand the quantum well below the Fermi level, thus improving the device performance. The GaN MIS-HEMT with SiON demonstrated a high maximum drain-source current density (I-DS,I-max) of > 1 A/mm, a breakdown voltage of 750 V at a drain leakage current of 1 mu A/mm, and a well transfer characteristics. The dynamic ON-resistance only increased slightly under a high quiescent bias of 100 V.
Improved Reliability of GaN HEMTs Using N-2 Plasma Surface Treatment
(2015)
Liu, S. C.
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Dai, G. M.
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Chang, E. Y.
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材料科學與工程學系
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Department of Materials Science and Engineering
In this work, we present a systematic study on AlGaN surface treatment by N-2 plasma treatment prior to SiN deposition to enhance the reliability of the AlGaN/GaN MIS-HEMT. N-2 plasma treatment can effective remove surface impurities and discharge at the GaN surface, thus improving the SiN/GaN interface quality. With this technique, the GaN MIS-HEMT exhibits excellent reliability after high-gate-bias stress, high-drain-bias stress, and continuously long-term switching.
InGaAsP quantum-wells saturable absorber for diode-pumped passively Q-switched 1.3-mu m lasers
(2006-09-01)
Li, A.
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Liu, S. C.
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Su, K. W.
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Liao, Y. L.
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Huang, S. C.
We demonstrate the first use of InGaAsP quantum wells as a saturable absorber in the Q-switching of a diode-pumped Nd-doped 1.3 mu m laser. The barrier layers of the InGaAsP quantum-well device are designed to be a strong absorber for the suppression of the transition channel at 1.06 mu m. With an incident pump power of 1.8 W, an average output power of 160 mW with a Q-switched pulse width of 19 ns at a pulse repetition rate of 38 kHz was obtained.
Low Current Collapse and Low Leakage GaN MIS-HEMT Using AlN/SiN as Gate Dielectric and Passivation Layer
(2014)
Liu, S. C.
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Wong, Y. Y.
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Lin, Y. C.
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Chang, E. Y.
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材料科學與工程學系
An effective passivation and gate insulator with low current collapse and improved dynamic ON-state resistance (R-ON) for GaN MIS-HEMT is demonstrated in this work. The structure of passivation and gate insulator is fabricated by 4-nm SiN as the first passivation layer and 1-nm AlN. The bilayer AlN/SiN structure integrates the advantages of SiN and AlN. SiN passivation has been proved to effectively reduce GaN surface states. AlN has high bandgap of similar to 6.2 eV which can suppress leakage current. Hence, the unfavorable effects such as trapping effect and leakage current which will induce current collapse and are effectively suppressed by using AlN/SiN bilayer thin film. A GaN MIS-HEMT with AlN/SiN passivation and gate dielectric exhibits improved I. V characteristics, low leakage current, low current collapse, and improved dynamic RON at high quiescent drain bias of 100 V.
Low Leakage Current GaN MIS-HEMT with SiNx Gate Insulator using N-2 Plasma Treatment
(2013)
Liu, S. C.
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Wang, H. C.
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Chang, E. Y.
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材料科學與工程學系
;
Department of Materials Science and Engineering
In this work, an effective N-2 plasma treatment for suppressing leakage current in GaN MIS-HEMT has been demonstrated. We observed an important issue of leakage current from the SiNx/GaN interface. To investigate the leakage current mechanisms, we measured the leakage current from all the possible paths in the device structure, such as gate, mesa isolation, and drain leakage. The current-voltage measurement results reveal a severe leakage path at the SiNx/GaN interface after SiNx deposited on the GaN surface without N-2 plasma treatment. By using N-2 plasma treatment, we succeed in suppressing the leakage current and effectively improve breakdown voltage. A significant performance improvement of GaN MIS-HEMT with very low leakage current has been achieved through the N-2 plasma treatment.
Low-temperature study of lasing characteristics for 1.3-mu m AlGaInAs quantum-well laser pumped by an actively Q-switched Nd:YAG laser
(2010)
Su, K. W.
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Chen, Yi-Fan
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Huang, S. C.
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Li, A.
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Liu, S. C.
We report a low-temperature 1.3 mu m AlGaInAs quantum-well laser pumped by a 1.06 mu m active Q-switched laser quenched by a low-temperature vacuum system. An average power of 330mW is achieved at temperature as low as 233K compared to the average power of 50mW obtained at room-temperature without cooling device both at pumping repetition rate of 30 kHz. And the average rate of gain peak shift was found to be 0.47 nm/K between 293-133 K.