Browsing by Author "Chen, Szu-Hung"

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An Investigation of Carbon-Doping-Induced Current Collapse in GaN-on-Si High Electron Mobility Transistors
(2016-06-01)
Tzou, An-Jye
;
Hsieh, Dan-Hua
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Chen, Szu-Hung
;
Liao, Yu-Kuang
;
Li, Zhen-Yu
This paper reports the successful fabrication of a GaN-on-Si high electron mobility transistor (HEMT) with a 1702 V breakdown voltage (BV) and low current collapse. The strain and threading dislocation density were well-controlled by 100 pairs of AlN/GaN superlattice buffer layers. Relative to the carbon-doped GaN spacer layer, we grew the AlGaN back barrier layer at a high temperature, resulting in a low carbon-doping concentration. The high-bandgap AlGaN provided an effective barrier for blocking leakage from the channel to substrate, leading to a BV comparable to the ordinary carbon-doped GaN HEMTs. In addition, the AlGaN back barrier showed a low dispersion of transiently pulsed I-D under substrate bias, implying that the buffer traps were effectively suppressed. Therefore, we obtained a low-dynamic on-resistance with this AlGaN back barrier. These two approaches of high BV with low current collapse improved the device performance, yielding a device that is reliable in power device applications.
Broadband and wide angle antireflection of sub-20 nm GaAs nanograss
(2012-06-01)
Ravipati, Srikanth
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Shieh, Jiann
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Ko, Fu-Hsiang
;
Yu, Chen-Chieh
;
Chen, Hsuen-Li
GaAs nanograss with diameters of less than 20 nm has been fabricated using a simple, one-step, maskless plasma etching-based approach. GaAs nanograss exhibits remarkable broadband antireflection properties, which arise from the graded refractive index between air and the GaAs substrate by the nanograss layer. Moreover, GaAs nanograss shows less sensitivity to transverse electric polarized light and transverse magnetic polarized light over a wide range of incident angles compared to the strong variation in a bare GaAs substrate. These effects show that sub-20 nm GaAs nanograss with lengths of approximately 200 nm has an enhanced absorption of 98-100% when the incident energy is larger than the GaAs bandgap (lambda = 240-873 nm) and an enhanced absorption of 72-98% when the incident energy is less than the bandgap (lambda = 873-2400 nm). Our simple, one-step, and maskless plasma etching method opens a promising approach for the direct implementation of broad omnidirectional antireflective surfaces on solar cells and various optoelectronic devices to improve device performance.
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
;
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-Efficiency AlGaAs/InGaAs/GaAs Pseudomorphic High-Electron-Mobility Transistors Using a Sub-Micron Deep-UV T-Shaped Gate Technology
(2000)
Lai, Yeong-Lin
;
Chang, Edward Yi
;
Lee, Di-Houng
;
Chen, Szu-Hung
;
材料科學與工程學系
A class-B AlGaAs/InGaAs/GaAs pseudomorphic power high-electron-mobility transistor (HEMT) with high power performance has been developed. A simple fabrication method of a sub-micron T-shaped gate using the deep-UV lithography technology with tri-layer photoresists is presented for improvement of efficiency and gain of a pseudomorphic power HEMT. The AlGaAs/InGaAs/GaAs multinary compound material structure of the HEMT was grown by the molecular-beam epitaxy (MBE). The HEMT with a gate width of 3.36 mm and a gate length of 0.5 mu m exhibits a transconductance of 383 mS/mm. The saturation drain-to-source current (IDss) is 265 mA/mm. At an operation frequency of 1.9 GHz, the device demonstrates a power-added efficiency (PAE) of 65% at a drain bias of 1.2 V and a quiescent drain current of 30 mA (3.37% I-DSS). The state-of-the-art power characteristics are, for the first time, achieved by the AlGaAs/InGaAs/GaAs pseudomorphic power HEMT using a sub-micron deep-UV T-shaped gate technology.
High-performance In0.52Al0.48As/In(0.6)Ga(0.)4As power metamorphic HEMT for Ka-band applications
(2006)
Chang, Chia-Yuan
;
Chang, Edward Yi
;
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.
InAlAs/InGaAs metamorphic high electron mobility transistor with Cu/Pt/Ti gate and Cu airbridges
(2007-05-01)
Chang, Chun-Wei
;
Chen, Po-Chou
;
Lee, Huang-Ming
;
Chen, Szu-Hung
;
Sahoo, Kartik Chandra
The use of a Cu/Pt/Ti Schottky contact structure and Cu-based airbridges for high-frequency metamorphic high electron mobility transistor (MHEMT) is successfully developed. The material characteristics of the Cu/Pt/Ti Schottky contact on i-InAlAs were studied. Judging from the results of the X-ray diffraction analysis, Auger electron spectroscopy, and transmission electron microscopy, the Cu/Pt/Ti Schottky contact structure on InAlAs was very stable after annealing at 350 degrees C. However, after 400 degrees C annealing, the reaction of copper with the layers underneath started to occur and formed the Cu4Ti phase. The Cu-metallized MHEMT using the proposed Cu/Pt/Ti T-gate structure and Cu-based airbridges has a saturated drain current of 673 mA/mm and a maximum transconductance of 750 mS/mm. The gate to drain breakdown voltage measured was 14.5 V at a gate reverse current of -1 mA/mm. The device also demonstrated a cutoff frequency F-t of 90 GHz and a maximum frequency of oscillation F-max of 165 GHz. An MHEMT with a Au/Pt/Ti gate was fabricated and compared with an MHEMT fabricated with the proposed Cu/Pt/Ti gate. These two kinds of MHEMTs showed similar F-t and F-max. These results demonstrate that the Cu/Pt/Ti T-gate and Cu-based airbridges can be used for MHEMT fabrication with excellent electrical characteristics.
Method for forming a semiconductor structure having nanometer line-width
(2008-10-16)
Chen, Szu-Hung
;
Lien, Yi-Chung
;
Chang, Edward Yi
A method for forming a semiconductor structure having a deep sub-micron or nano scale line-width is disclosed. Structure consisting of multiple photoresist layers is first formed on the substrate, then patterned using adequate exposure energy and development condition so that the bottom photoresist layer is not developed while the first under-cut resist groove is formed on top of the bottom photoresist layer. Anisotropic etching is then performed at a proper angle to the normal of the substrate surface, and a second resist groove is formed by the anisotropic etching. Finally, the metal evaporation process and the lift-off process are carried out and the Γ-shaped metal gate with nano scale line-width can be formed.
Method for forming gate pattern for electronic device
(2007-03-22)
Chen, Szu-Hung
;
Kuo, Chien-I
;
Chang, Edward Yi
A method for forming a gate pattern for an electronic device, comprising steps of: providing a substrate, whereon a first photo-resist layer is formed; performing a first photo-lithography process so as to form a first pattern with a first width on the substrate; forming a second photo-resist layer, covering the first pattern and the first photo-resist layer on the substrate; and performing a second photo-lithography process, which is shifted from the first photo-lithography process, so as to form a second pattern with a second width on the substrate; wherein the second width is smaller than the first width.
Microstructural Characterization of Multilayer Metal Stack on InGaAs/InP Contact
(2020-08-01)
Hsu, Chih-Lin
;
Wu, Yewchung Sermon
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Chen, Szu-Hung
;
Lin, Kun-Lin
;
材料科學與工程學系
Al/InGaAs, Al/Ti/InGaAs, and Al/Ni/InGaAs contacts were prepared by conducting rapid thermal annealing at different temperatures, and the interfacial reaction was characterized using x-ray diffraction, atomic force microscopy, and transmission electron microscopy. The specific contact resistivity of the metal film contacts onn-InGaAs was determined using a circular transmission line measurement. The Al/Ni/InGaAs, Al/Ti/InGaAs, and Al/InGaAs stack contacts remained stable even after the samples were subjected to annealing at 400 degrees C. When the annealing temperature increased to 600 degrees C, Al began melting and clustering due to the formation of Al(Ga) to form Al/InGaAs. An AlNi phase was formed at the interfaces of an Al/Ni/InGaAs contact when it was annealed above 400 degrees C, thus causing the specific resistance and roughness to increase dramatically. Each element of the Al/Ti/InGaAs contact began diffusing when it was annealed beyond 400 degrees C, and an Al3Ti phase was formed above 500 degrees C. The formation of Al3Ti led to the increase in the specific resistance and roughness. Moreover, the as-deposited Al/Ni/InGaAs, Al/Ti/InGaAs and Al/InGaAs samples had specific resistances of 1.11 x 10(-5) omega cm(2), 5.11 x 10(-5) omega cm(2), and 1.14 x 10(-4) omega cm(2), respectively. These results reveal that to develop the Al/Ti/InGaAs and Al/Ni/InGaAs stacks on InGaAs with a low parasitic resistance, the processing temperature should be lower than 400 degrees C.
Non-thermal alloyed ohmic contact process of GaN-based HEMTs by pulsed laser annealing
(2016-05)
Tzou, An-Jye
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Hsieh, Dan-Hua
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Chen, Szu-Hung
;
Li, Zhen-Yu
;
Chang, Chun-Yen
We have demonstrated Si implantation incorporation into GaN HEMTs with a non-alloyed ohmic contact process. We optimized the power density of pulsed laser annealing to activate implanted Si dopants without a thermal metallization process. The experimental results show that the GaN surface will be reformed under the high power density of the illumination conditions. It provides a smooth surface for following contact engineering and leads to comparable contact resistance. The transmission line model (TLM) measurement shows a lower contact resistance to 6.8. x. 10(-7) Omega . cm(2) via non-alloyed contact technology with significantly improved surface morphology of the contact metals. DC measurement of HEMTs shows better current and on-resistance. The on-resistance could be decreased from 2.18 to 1.74 m Omega-cm(2) as we produce a lower contact resistance. Pulsed laser annealing also results in lower gate leakage and smaller dispersion under a pulse I-V measurement, which implies that the density of the surface state is improved.
Record-high 121/62 mu A/mu m on-currents 3D stacked epi-like Si FETs with and without metal back gate
(2013)
Yang, Chih-Chao
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Chen, Szu-Hung
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Shieh, Jia-Min
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Huang, Wen-Hsien
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Hsieh, Tung-Ying
A sequential layered integration technology that can fabricate 3D stackable epi-like Si FETs with and without metal back gate (MBG) under sub-400 degrees C are proposed in this article. With laser crystallized epi-like Si and CMP thinning processes for channel fabrication, 3D stackable ultra thin body (UTB) n/p-MOSFETs with low-subthreshold swings (88 and 121 mV/dec.) and high on-currents (121 and 62 liA/Iim) are demonstrated. With additional metal back gate structure, UTB devices can be desirably operated in a positive or negative threshold voltage range with gamma values of 0.51 (n-MOSFETs) and 0.56 (p-MOSFETs) for favoring its applications in 3D logic circuits. In addition, such thin and high quality channel and metal back gate scheme is not only promising for conventional p-n junction device but also junctionless (JL) scheme, which can simplify the fabrication and achieve further scaling.
Suspended Ge Gate-All-Around Nanowire nFETs with Junction Isolation on Bulk Si
(2016)
Wan, Chia-Chen
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Luo, Guang-Li
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Hsu, Shu-Han
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Hung, Kuo-Dong
;
Chu, Chun-Lin
Replacing Si channel with selective epi-Ge in mainstream bulk FinFETs can be a cost-effective solution for sub-7 nm node, but is facing severe challenges because of poor isolation to Si substrates. We demonstrate a suspended Ge gate-all-around (GAA) nanowire nFET (nNWFET) technology with junction isolation on bulk Si. Because of the low junction leakage provided by an embedded Si junction, improved electrostatics of GAA structure utilizing surrounding high-mobility {111} surfaces, and a dislocation-free channel by selectively removing the defective Ge/Si interface, a high current on/off ratio (I-ON/I-OFF of 5x10(5), which is comparable to the state-of-the-art Ge nFETs on Ge-on-insulator (GeOI), is first demonstrated using a bulk FinFET-compatible process.
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.