Browsing by Author "Lin, Tai-Wei"

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Demonstrating 1 nm-oxide-equivalent-thickness La2O3 and HfO2 multi-layer composite oxides on In0.53Ga0.47As MOS capacitor
(2016-01-08)
Wu, Wen-Hao
;
Lin, Yueh-Chin
;
Hou, Tzu-Ching
;
Lin, Tai-Wei
;
Hsu, Hisang-Hua
The use of a high k composite dielectric composed of La2O3 and HfO2 layers as the gate dielectric for In0.53Ga0.47As MOS application is proposed. Two multi-layer structures of La2O3 (1 nm)/HfO2 (1 nm) and La2O3 (0.5 nm)/HfO2 (0.5 nm) were deposited and annealed at 450 and 500 degrees C for device performance comparison. X-ray photoelectron spectroscopy, TEM and C-V measurements were used for the interface analysis between the oxide and the semiconductor. Finally, a 1 nm equivalent-oxide-thickness dielectric with small hysteresis of 88 mV and D-it of 1.9 x 10(12) cm(-2) eV(-1) was achieved for six layers of an La2O3 (0.5 nm)/HfO2 (0.5 nm) composite oxide structure on an In0.53Ga0.47As MOS capacitor with a post-deposition annealing temperature of 450 degrees C.
Improved linearity and reliability in GaN metal-oxide-semiconductor high-electron-mobility transistors using nanolaminate La2O3/SiO2 gate dielectric
(2016-04)
Hsu, Ching-Hsiang
;
Shih, Wang-Cheng
;
Lin, Yueh-Chin
;
Hsu, Heng-Tung
;
Hsu, Hisang-Hua
Improved device performance to enable high-linearity power applications has been discussed in this study. We have compared the La2O3/SiO2 AlGaN/GaN metal-oxide-semiconductor high-electron-mobility transistors (MOS-HEMTs) with other La2O3-based (La2O3/HfO2, La2O3/CeO2 and single La2O3) MOS-HEMTs. It was found that forming lanthanum silicate films can not only improve the dielectric quality but also can improve the device characteristics. The improved gate insulation, reliability, and linearity of the 8 nm La2O3/SiO2 MOS-HEMT were demonstrated. (C) 2016 The Japan Society of Applied Physics
Improved linearity and reliability in GaN metal-oxide-semiconductor high-electron-mobility transistors using nanolaminate La2O3/SiO2 gate dielectric
(2016-04-01)
Hsu, Ching-Hsiang
;
Shih, Wang-Cheng
;
Lin, Yueh-Chin
;
Hsu, Heng-Tung
;
Hsu, Hisang-Hua
Improved device performance to enable high-linearity power applications has been discussed in this study. We have compared the La2O3/SiO2 AlGaN/GaN metal-oxide-semiconductor high-electron-mobility transistors (MOS-HEMTs) with other La2O3-based (La2O3/HfO2, La2O3/CeO2 and single La2O3) MOS-HEMTs. It was found that forming lanthanum silicate films can not only improve the dielectric quality but also can improve the device characteristics. The improved gate insulation, reliability, and linearity of the 8 nm La2O3/SiO2 MOS-HEMT were demonstrated. (C) 2016 The Japan Society of Applied Physics
Interfacial Charge Carrier Dynamics in Core-Shell Au-CdS Nanocrystals
(2010-07-08)
Yang, Ting-Ting
;
Chen, Wei-Ta
;
Hsu, Yung-Jung
;
Wei, Kung-Hwa
;
Lin, Tai-Yuan
The interfacial charge carrier dynamics for core-shell Au-CdS nanocrystals with various shell thicknesses were investigated and presented. Due to the difference in band structures between Au and CdS, a pronounced photoinduced charge separation took place at the interface of Au and CdS, resulting in the electron-charged Au core and the hole-enriched CdS shell. The electron-charging of Au core in Au-CdS nanocrystals was revealed with the corresponding XPS analysis and photocurrent measurement. Time-resolved PL spectra were measured to quantitatively analyze the electron transfer event between CdS shell and Au core for Au-CdS nanocrystals. An increase in the electron-transfer rate constant was observed for Au-CdS nanocrystals with increasing shell thickness, probably due to the less pronounced electron hole interaction of thicker CdS, which enabled a fuller extent of participation of photoexcited electrons in the charge separation process. On the other hand, the hole-enriched CdS shell of Au-CdS nanocrystals upon light illumination was characterized with a photocatalytic process. The photocatalytic activity of Au-CdS nanocrystals was found to increase with increasing shell thickness, attributable to the greater capability of light absorption achieved by the extensive growth of the CdS shell. The correlation of photocatalytic activity with the shell thickness of Au-CdS nanocrystals corresponded well with that of the electron-transfer rate constant. As compared to the relevant commercial products like N-doped P-25 TiO(2), and CdS powders, the as-synthesized Au-CdS nanocrystals,exhibited superior photocatalytic performance under visible light illumination, demonstrating their potential as an effective visible-light-driven photocatalyst. Furthermore, the result of performance evaluation under natural sunlight shows that the present Au-CdS nanocrystals can be used as highly efficient photocatalysts which may practically harvest energy from sunlight.