Browsing by Author "Hsieh, Yen-Chang"

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AlGaAs/InGaAs high electron mobility transistor grown on Si substrate with Ge/Ge(x)Si(1-x) metamorphic buffer layers
(2008-09-01)
Chang, Edward Yi
;
Huang, Jui-Chien
;
Lin, Yueh-Chin
;
Hsieh, Yen-Chang
;
Chang, Chia-Yuan
Al(0.12)Ga(0.88)As/In(0.18)Ga(0.82)As high-electron-mobility transistor (HEMT) growth oil a Si substrate using the Ge/Ge(x)Si(1-x) buffer is demonstrated. This is the first demonstration of Al(0.12)Ga(0.88)As/In(0.18)Ga(0.82)As HEMT growth on a Ge/Ge(x)Si(1-x) metamorphic buffer layer. The electron mobility ill tile In(0.18)Ga(0.82)As channel of the HEMT sample was 3.550cm(2)/(Vs). After fabrication. the HEMT device demonstrated a saturation current of 150mA/mm with a transconductance 01 155mS/ inns. The wel behaved characteristics of the HEMT device oil the Si substrate are believed to be due to the very thin buffer layer achieved and the lack of tile antiphase boundary (APB) formation and Ge diffusion into the GaAs layers.
AlGaAs/InGaAs high electron mobility transistor grown on Si substrate with Ge/GexSi1-x metamorphic buffer layers
(2008-09-01)
Chang, Edward Yi
;
Huang, Jui-Chien
;
Lin, Yueh-Chin
;
Hsieh, Yen-Chang
;
Chang, Chia-Yuan
Al0.12Ga0.88As/In0.18Ga0.82As high-electron-mobility transistor (HEMT) growth oil a Si substrate using the Ge/GexSi1-x buffer is demonstrated. This is the first demonstration of Al0.12Ga0.88As/In0.18Ga0.82As HEMT growth on a Ge/GexSi1-x metamorphic buffer layer. The electron mobility ill tile In0.18Ga0.82As channel of the HEMT sample was 3.550cm(2)/(Vs). After fabrication. the HEMT device demonstrated a saturation current of 150mA/mm with a transconductance 01 155mS/ inns. The wel behaved characteristics of the HEMT device oil the Si substrate are believed to be due to the very thin buffer layer achieved and the lack of tile antiphase boundary (APB) formation and Ge diffusion into the GaAs layers.
Copper-airbridged low-noise GaAs PHEMT with Ti/WNx/Ti diffusion barrier for high-frequency applications
(2006-08-01)
Lee, Cheng-Shih
;
Lien, Yi-Chung
;
Chang, Edward Yi
;
Chang, Huang-Choung
;
Chen, Szu-Houng
A GaAs pseudomorphic HEMT (PHEMT) with Cu-metallized interconnects was successfully developed. Sputtered WNx was used as the diffusion barrier and Ti was used as the adhesion layer to improve the adhesion between WNx/Cu interface in the thin-metal structure. After copper metallization, the PHEMTs were passivated with silicon nitride to avoid copper oxidation. The Cu-airbridged PHEMT showed the saturation I-DS was 250 mA/mm and the g(m) was 456 mS/mm. The Ti adhesion layer plays a significant role on the g(m) and V-p uniformity of the Cu-metallized PHEMTs. The GaAs PHEMTs with Ti/WNx/Ti/Cu multilayer have better noise figure and associated gain than those of the devices without the Ti adhesion layer. The fabricated Cu-metallized GaAs PHEMT with Ti/WNx/Ti/Cu multilayer has a noise figure of 0.76 dB and an associated gain of 8.8 dB at 16 GHz. The cutoff frequency (f(T)) is 70 GHz when biased at V-DS = 1.5 V. These results show that the Ti/WNx/Ti multilayer can serve as a good diffusion barrier for Cu metallization process of airbridge interconnects on GaAs low-noise PHEMTs.
High-speed GaAs metal gate semiconductor field effect transistor structure grown on a composite Ge/Ge(x)Si(1-x)/Si substrate
(2007-04-15)
Luo, Guang-Li
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Hsieh, Yen-Chang
;
Chang, Edward Yi
;
Pilkuhn, M. H.
;
Chien, Chao-Hsin
In this study we used a low-pressure metal organic vapor phase epitaxy method to investigate the growth of GaAs metal gate semiconductor field effect transistor (MESFET) structures on a Si substrate. The buffer layer between the Si substrate and the grown GaAs epitaxial layers was a composite Ge/Si(0.05)Ge(0.95)/Si(0.1)Ge(0.9) metamorphic layer. We used transmission electron microscopy to observe the microstructures formed in the grown GaAs/Ge/Si(x)Ge(1-x)/Si material and atomic force microscopy to analyze the surface morphology and the formation of antiphase domains in the GaAs epitaxial layers. The measured Hall electron mobility in the channel layer of a MESFET structure grown on a 6 degrees misoriented Si substrate was 2015 cm(2) V(-1) s(-1) with a carrier concentration of 5.0x10(17) cm(-3). The MESFET device fabricated on this sample exhibited good current-voltage characteristics.
Thermal stability of Ti/Pt/Cu Schottky contact on InAlAs layer
(2006-08-21)
Lien, Yi-Chung
;
Chang, Edward Yi
;
Chen, Szu-Hung
;
Chu, Li-Hsin
;
Chen, Po-Chou
Electrical characteristics and thermal stability of the Ti/Pt/Cu Schottky contact on InAlAs were investigated. The Ti/Pt/Cu Schottky contact had comparable electrical properties compared to the conventional Ti/Pt/Au contact after annealing. As judged from the material analysis, the Ti/Pt/Cu on InAlAs after 350 degrees C annealing showed no diffusion sign into the InAlAs. After 400 degrees C annealing, the interfacial mixing of Cu and the underlying layers occurred and resulted in the formation of Cu4Ti. The results show that Ti/Pt/Cu Schottky contact using platinum as the diffusion barrier is very stable up to 350 degrees C annealing and can be used for InAlAs/InGaAs high-electron mobility transistors and monolithic microwave integrated circuits. (c) 2006 American Institute of Physics.