Browsing by Author "Chu, Li-Hsin"

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Copper-airbridged low-noise GaAs PHEMT with Ti/WNx/Ti diffusion barrier for high-frequency applications
(2006-08-01)
Lee, Cheng-Shih
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Lien, Yi-Chung
;
Chang, Edward Yi
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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.
Double delta-doped enhancement-mode InGaP/AlGaAs/InGaAs pseudomorphic high electron mobility transistor for linearity application
(2006-09-01)
Chu, Li-Hsin
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Hsu, Heng-Tung
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Chang, Edward-Yi
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Lee, Tser-Lung
;
Chen, Sze-Hung
A high linearity and high efficiency enhancement-mode InGaP/AlGaAs/InGaAs pseudomorphic high electron mobility transistor (PHEMT) for single supply operation has been developed. The low voltage operation is achieved by the very low knee voltage of the device and the linearity is improved by the optimizing concentrations of the two 3 delta-doped layers. Biased at drain-to-source voltage V-DS = 2V, the fabricated 0.5 x 200 mu m(2) device exhibited a maximum transconductance of 448 mS/mm. The measured minimum noise figure (NFmin) was 0.86 dB with 12.21 dB associated gain at 10 GHz. The device shows a high output third-order intercept point (OIP3)-P-1dB of 13.2 dB and a high power efficiency of 35% when under wideband code-division multiple-access (W-CDMA) modulation signal.
Fabrication of 0.15-mu m Gamma-shaped gate In0.52Al0.48As/In0.6Ga0.4As metamorphic HEMTs using DUV lithography and tilt dry-etching technique
(2007-02-01)
Lien, Yi-Chung
;
Chen, Szu-Hung
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Chang, Edward Yi
;
Lee, Ching-Ting
;
Chu, Li-Hsin
An In0.52Al0.48As/In0.6Ga0.4As metamorphic high-electron mobility transistor (MHEMT) with 0.15-mu m Gamma-shaped gate using deep ultraviolet lithography and tilt dry-etching technique is demonstrated. The developed submicrometer gate technology is simple and of low cost as compared to the conventional E-beam lithography or other hybrid techniques. The gate length is controllable by adjusting the tilt angle during the dry-et ching process. The fabricated 0.15-mu m In0.52Al0.48As/In0.6Ga0.4As MHEMT using this novel technique shows a saturated drain-source current of 680 mA/mm and a transconductance of 728 mS/mm. The f(T) and f(max) of the MHEMT are 130 and 180 GHz, respectively. The developed technique is a promising low-cost alternative to the conventional submicrometer E-beam gate technology used for the fabrication for GaAs MHEMTs and monolithic microwave integrated circuits.
High-performance In0.52Al0.48As/In(0.6)Ga(0.)4As power metamorphic HEMT for Ka-band applications
(2006)
Chang, Chia-Yuan
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Chang, Edward Yi
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Lien, Yi-Chung
;
Miyamoto, Yasuyuki
;
Chen, Szu-Hung
A 70-nm In0.52Al0.48As/In0.6Ga0.4As power MHEMT with double delta-doping was fabricated and evaluated. The device has a high transconductance of 827 mS/mm. The saturated drain-source current of the device is 890 mA/mm. A current gain cutoff frequency (f(T)) of 200 GHz and a maximum oscillation frequency of 300 GHz were achieved due to the nanometer gate length and the high Indium content in the channel. When measured at 32 GHz, the 4 x 40 mu m device demonstrates a maximum output power of 14.5 dBm with P1dB of 11.1 dBm and the power gain is 9.5 dB. The excellent DC and RF performance of the 70-nm MHEMT shows a great potential for Ka-band power applications.
High-performance In0.52Al0.48As/In0.6Ga0.4As power metamorphic high electron mobility transistor for Ka-band applications
(2007-06-01)
Chang, Chia-Yuan
;
Chang, Edward Yi
;
Lien, Yi-Chung
;
Miyamoto, Yasuyuki
;
Kuo, Chien-I
A 70nm In0.52Al0.48As/In0.6Ga0.4As power metamorphic high electron mobility transistor (MHEMT) with a double delta-doping structure was fabricated and evaluated. The device has a high transconductance of 827mS/mm. The saturated drain-source current of the device is 890mA/mm. A current gain cutoff frequency (f(T)) of 200GHz and a maximum oscillation frequency (f(max)) of 300GHz were achieved owing to the nanometer gate length and high indium content in the channel. When measured at 32 GHz, the 0.07x160 mu m(2) device demonstrates a maximum output power of 14.5dBm (176mW/mm) and a P I dB of 11.1dBm (80mW/mm) with a 9.5dB power gain. The excellent DC and RF performance of the 70mn MHEMT are comparable to those of InP-based HEMTs and show the great potential for Ka-band power applications.
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.