Browsing by Author "Chang, Po-Chun"

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AlGaN/GaN HEMTs With Damage-Free Neutral Beam Etched Gate Recess for High-Performance Millimeter-Wave Applications
(2016-11)
Lin, Yen-Ku
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Noda, Shuichi
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Lo, Hsiao-Chieh
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Liu, Shih-Chien
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Wu, Chia-Hsun
The electrical performances of gate-recessed AlGaN/GaN high-electron mobility transistors (HEMTs) fabricated using the damage-free neutral beam etching (NBE) method are demonstrated. The NBE method could eliminate the plasma-induced defects generated by irradiating ultraviolet/VUV photons in the conventional inductively coupled plasma reactive ion etching method. The AlGaN/GaN HEMT device fabricated using the new gate recess process exhibited superior electrical performances, including a maximum drain current density (I-DS,I-max) of 1.54 A/mm, low 1/f noise, a current-gain cutoff frequency (f(T)) of 153 GHz, a maximum frequency of oscillation (f(MAX)) of 167 GHz, and a minimum noise figure (NFmin) of 3.28 dB with an associated gain (G(AS)) of 5.06 dB at 54 GHz. Such superior characteristics confirm the inherent advantages of adopting the damage-free NBE process in fabricating GaN devices for millimeter-wave applications.
AlGaN/GaN HEMTs With Damage-Free Neutral Beam Etched Gate Recess for High-Performance Millimeter-Wave Applications (vol 37, pg 1395, 2016)
(2017-01)
Lin, Yen-Ku
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Noda, Shuichi
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Lo, Hsiao-Chieh
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Liu, Shih-Chien
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Wu, Chia-Hsun
AlGaN/GaN HEMTs With Damage-Free Neutral Beam Etched Gate Recess for High-Performance Millimeter-Wave Applications (vol 37, pg 1395, 2016)
(2017-01)
Lin, Yen-Ku
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Noda, Shuichi
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Lo, Hsiao-Chieh
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Liu, Shih-Chien
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Wu, Chia-Hsun
Effects of layer sequence and postdeposition annealing temperature on performance of La2O3 and HfO2 multilayer composite oxides on In0.53Ga0.47As for MOS capacitor application
(2014-03-01)
Wu, Wen-Hao
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Lin, Yueh-Chin
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Chuang, Ting-Wei
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Chen, Yu-Chen
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Hou, Tzu-Ching
In this paper, we report on high-k composite oxides that are formed by depositing multiple layers of HfO2 and La2O3 on In0.53Ga0.47As for MOS device application. Both multilayer HfO2 (0.8 nm)/La2O3 (0.8 nm)/In0.53Ga0.47As and La2O3 (0.8 nm)/HfO2 (0.8 nm)/In0.53Ga0.47As MOS structures were investigated. The effects of oxide thickness and postdeposition annealing (PDA) temperature on the interface properties of the composite oxide MOS capacitors were studied. It was found that a low CET of 1.41 nm at 1 kHz was achieved using three-layer composite oxides. On the other hand, a small frequency dispersion of 2.8% and an excellent D-It of 7.0 Chi 10(11)cm(-2).eV(-1) can be achieved using multiple layers of La2O3 (0.8 nm) and HfO2 (0.8 nm) on the In0.53Ga0.47As MOS capacitor with optimum thermal treatment and layer thickness. (C) 2014 The Japan Society of Applied Physics
Electrical Analysis and PBTI Reliability of In0.53Ga0.47As MOSFETs With AlN Passivation Layer and NH3 Postremote Plasma Treatment
(2016-09)
Chang, Po-Chun
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Luc, Quang-Ho
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Lin, Yueh-Chin
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Liu, Shih-Chien
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Lin, Yen-Ku
We report a notable improvement in performance, electron transport, and reliability of HfO2/In0.53Ga0.47As nMOSFETs using a plasma-enhanced atomic layer deposition AlN interfacial passivation layer (IPL) and NH3 postremote plasma treatment (PRPT). The interface state density Dit decreased by approximately one order of magnitude from 6.1x10(12) to 4x10(11) cm(-2)eV(-1), and the border trap density N-bt also declined ten times from 2.8x10(19) to 2.7x10(18) cm(-3), resulting in the reduction of the accumulation frequency dispersion and eliminate the inversion hump in C-V characteristics, and thus improves the device performances. Furthermore, positive bias temperature instability stress indicates that the sample with the AlN IPL and NH3 PRPT is more reliable than the sample without any IPL and plasma treatment. During PBT stress, a smaller threshold voltage shift and less transconductance degradation were observed for the sample with the AlN IPL and NH3 PRPT. In addition, the maximum overdrive voltage for a ten-year operating lifetime increased from 0.19 to 0.41 V.
Electrical Improvement of MIS Capacitor with HfAlOx Gate Dielectrics Treated by Dual Plasma Treatment
(2012)
Deng, I-Chung
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Chang, Kow-Ming
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Chang, Ting-Chia
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Chang, Po-Chun
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Huang, Bo-Wen
High dielectric constant materials (high-k) such as Hf-based thin films are the promising candidates for 45-nm CMOS technology. It has been described that nitridation processes could improve thermal stability and dielectric constants of Hf-based dielectrics. Furthermore, fluorine incorporation into high-k dielectric was also proposed in order to suppress leakage current and passivate defects. In this study, we examined dual plasma treatment (CF4 pretreatment and N-2 post-treatment) on HfAlOx thin films in order to improve electrical characteristics. Based on our experimental results, HfAlOx Metal-Insulator-Semiconductor (MIS) capacitor properties such as capacitance density, gate leakage current density, and hysteresis could be successfully improved. Compared to untreated samples, capacitance is 42.5% higher and gate leakage is suppressed about three orders when dual plasma treatment is used. According to this study, dual plasma treatment would be an effective technology to improve the electrical characteristic of HfAlOx thin films.
ETAHM: An energy-aware task allocation algorithm for heterogeneous multiprocessor
(2008)
Chang, Po-Chun
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Wu, I-Wei
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Shann, Jyh-Jiun
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Chung, Chung-Ping
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資訊工程學系
In demand of more computing power and less energy use, multiprocessor with power management facility emerges in embedded system design recently. Dynamic Voltage Scaling is such a facility that varies clock speed and supply voltage to save more energy. In this paper, we propose ETAHM to allocate tasks on a target multiprocessor system. In pursuit of global optimal solution, it mixes task scheduling, mapping and DVS utilization in one phase and couples ant colony optimization algorithm. Extensive experiments show ETAHM could save 22.71% more energy than CASPER [1], a state-of-the-art integrated framework that tackles the identical problem with genetic algorithm instead.
HfO2/AIN/ln(0.53)Ga(0.47)As MOS Devices Electrical Properties and Reliability Studies
(2016-01-01)
Yi-Chang, Edward
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Quang-Ho Luc
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Huy-Binh Do
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Chang, Po-Chun
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Lin, Yueh-Chin
In this article, we demonstrate plasma-enhanced atomic layer deposition (PEALD) as an effective passivation technique to establish high interfacial quality of high-kllnGaAs structures. Performing PEALD-AlN as an interfacial passivation layer (IPL), excellent capacitance-voltage (C-V) characteristics have been achieved for the HfO2/n, p-In0.53Ga0.47As MOSCAPs. The effects of AlN-IPL on the effective work function (EWF) of metal and band alignment of the HfO2/AlN/In0.53Ga0.47As structure have also been investigated. In addition, the multilayer TiNi alloys were applied as gate dielectric for a suitable metal EWF with a small work function variation (WFV). A sub-nm equivalent oxide thickness (EOT) HfO2/AlN/In0.53Ga0.47As MOS device with low density of interface states and low leakage current density was obtained utilizing AlN-IPL and post remote-plasma (PRP) gas as pre- and post-gate treatments in an in-situ ALD process. The device performance and reliability of HfO2/AlN/In0.53Ga0.47As nMOSFETs with in-situ PEALD treatments have also been characterized.
High-Performance GaN MOSHEMTs Fabricated With ALD Al2O3 Dielectric and NBE Gate Recess Technology for High Frequency Power Applications
(2017-06-01)
Lin, Yen-Ku
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Noda, Shuichi
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Huang, Chia-Ching
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Lo, Hsiao-Chieh
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Wu, Chia-Hsun
High-performance GaN metal-oxidesemi-conductor high-electron-mobility transistors (MOSHEMTs) using Al2O3 gate dielectric deposited by atomic layer deposition (ALD) and damage-free neutral beam etch (NBE) gate recess process for millimeter-wave power applications are demonstrated. The high-quality ALD Al2O3 reduces the gate leakage current of the device and the NBE method eliminates the plasma-induced defects in the nitride materials. The MOSHEMT device fabricated exhibits a high maximum drain current density (I-DS,I-max ) of 1.65 A/mm and a high peak extrinsic transconductance (g(m.ext) ) of 653 mS/mm. The MOSHEMT device also demonstrates excellent RF performances, including f(T)/f(MAX) = 183/191 GHz, NFmin = 2.56 dB with G(AS) = 5.61 dB at 54 GHz, and an output power density of 2.7 W/mm associated with a power-added efficiency of 20.9% and a linear power gain of 9.4 dB at 38 GHz. To the best of our knowledge, the noise performance at 54 GHz is the best reported so far for the AlGaN/GaN HEMTs.
High-Performance Normally-OFF GaN MIS-HEMTs Using Hybrid Ferroelectric Charge Trap Gate Stack (FEG-HEMT) for Power Device Applications
(2018-07-01)
Wu, Chia-Hsun
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Han, Ping-Cheng
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Liu, Shih-Chien
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Hsieh, Ting-En
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Lumbantoruan, Franky Juanda
A GaN metal-insulator-semiconductor-high electron mobility transistor (HEMT) using hybrid ferroelectric charge trap gate stack (FEG-HEMT) is demonstrated for normally-OFF operation. The ferroelectric (FE) polarization increases the number of trapped charges in the HfON charge trapping layer, leading to high positive threshold voltage (V-th) shift for the normally-OFF device. Besides, under the positive bias temperature instability (PBTI) test, the internal electric field induced by FE polarization causes smoother slope of the conduction band in FE gate stack, resulting in better V-th stability. With the proposed hybrid FE charge trap gate stack, the device exhibits a high V-th of +2.71 V at I-DS = 1 mu A/mm, a high maximum current density of 820 mA/mm and low on-resistance (R-ON) of 11.1 Omega . mm. The FE device also shows good V-th-temperature stability compared to the non-FE device results. Besides, a high current device with 40 A is also fabricated in this letter to demonstrate the feasibility of the proposed FEG-HEMT device for high power device application.
Improvement on Interface Quality and Reliability Properties of HfAlOx MIS Capacitor with Dual Plasma Treatment
(2012)
Chang, Kow-Ming
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Chang, Ting-Chia
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Chang, Po-Chun
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Huang, Bo-Wen
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Wu, Chien-Hung
HfO2 is considered a promising gate dielectric material for sub-45 nm CMOS technology. It has been reported that incorporate Al into HfO2 forming Hf aluminates in order to increase the crystallization temperature. However, the growth of the low-k interfacial layer at high-k/Si interface during high-k dielectric deposition would result in reliability degradation. Recently, incorporating nitrogen into HfAlOx gate dielectrics has beneficial effect on reliability performance. In addition, fluorine incorporation into high-k dielectrics also could have several improvements. In this study, dual plasma (CF4 pre-treatment and N-2 post-treatment) was performed on HfAlOx MIS capacitor in order to improve interface quality and the reliability properties. According to our experimental results, dual plasma treatment could improve interface quality and enhance reliability properties of HfAlOx thin films.
In-x Ga1-x As Materials for Post CMOS Application: Materials and Device Aspects
(2014)
Chang, Edward Yi
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Lin, Yueh-Chin
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Luc, Quang-Ho
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Trinh, Hai-Dang
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Yao, Jing-Neng
High mobility InxGa1-xAs material is one of the most promising candidates as channel material for post CMOS device applications. In this presentation, InxGa1-xAs material based MOS capacitors will be studied for possible applications for future III-V MOSFET, TFET and FINFET devices. To improve the gate leakage of the InxGa1-xAs MOSCAP, the combination of wet chemical treatment and in-situ trimethyl aluminum (TMA) pretreatment was found to be the most effective method for InxGa1-xAs surface cleaning to achieve a fully inverted InxGa1-xAs MOSCAP for post CMOS digital applications. In addition, a high-k composite oxide composed of La2O3 and HfO2 is investigated for InxGa1-xAs metal-oxide-semiconductor (MOS) capacitor application. The composite oxide was formed by depositing five layers of La2O3(0.8 nm)/HfO2(0.8 nm) on InxGa1-xAs with post deposition annealing at 500 degrees C. The MOS capacitors fabricated show good inversion behavior, high capacitance, low leakage current, with excellent interface trap density (D-it) of 7.0 x 10(11) cm(-2)eV(-1), small hysteresis of 200 mV and low capacitance equivalent thickness of 2.2 nm at 1 kHz were also achieved.
InGaAs Junctionless FinFETs With Self-Aligned Ni-InGaAs S/D
(2018-01-01)
Chang, Po-Chun
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Hsiao, Chih-Jen
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Lumbantoruan, Franky Juanda
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Wu, Chia-Hsun
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Lin, Yen-Ku
In this paper, the InGaAs junctionless (JL) FinFET with notable electrical performance is demonstrated. The device with W-fin down to 20 nm, EOT of 2.1 nm, and L-G = 60 nm shows high I-ON = 188 mu A/mu m at V-DD = 0.5 V and I-OFF = 100 nA/mu m, I-ON/I-OFF = 5 x 10(5), DIBL = 106 mV/V and SS = 96 mV/dec. The device also exhibits a decent extrinsic transconductance (G(m)) of 1142 mu S/mu m at V-DS of 0.5 V. This high performance is attributed to the moderate doping concentration to ensure the channel carriers could be effectively depleted and the low R-SD realized by self-aligned Ni-InGaAs alloy S/D. Furthermore, we also examine the temperature dependence of the main electrical parameters of the JL transistor.
InGaAs QW-MOSFET Performance Improvement Using a PEALD-AlN Passivation Layer and an In-Situ NH3 Post Remote-Plasma Treatment
(2017-03-01)
Chang, Po-Chun
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Luc, Quang-Ho
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Lin, Yueh-Chin
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Lin, Yen-Ku
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Wu, Chia-Hsun
In this letter, we report on the impact of a PEALD-AlN interfacial passivation layer (IPL) and an in-situ NH3 post remote-plasma (PRP) treatment onto InGaAs quantum-well MOSFETs with Ti/HfO2/InGaAs gate stack. Transistors with gate lengths down to 80 nm have been fabricated and characterized. Due to the excellent interfacial quality of HfO2/AIN/InGaAs, the subthreshold swing and the peak effective channel mobility have been improved to 93 mV/decade and 4253 cm2/Vs, respectively. The drain current has also shown a 4.6-fold enhancement, to 164mA/mm(I-OFF = 100 nA/mu m DD = 0.5V), compared with the HfO2 control device. The results also show that the HfO2/AIN device exhibits better immunity to short-channel effects (SCEs) than the HfO2 control device. Furthermore, during positive bias temperature instability stress, a smaller V-TH and a lower Gm were observed for the sample with an AIN IPL and NH3 PRP treatment, indicating that it is more reliable than the sample without any IPL or plasma treatment.
Inhibition of Periodontitis Induction Using a Stimuli-Responsive Hydrogel Carrying Naringin
(2017-02-01)
Chang, Po-Chun
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Chao, Yi-Chi
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Hsiao, Meng-Hsuan
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Chou, Hao-Syun
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Jheng, Yi-Han
Background: Developing a drug carrier with favorable handling characteristics that can respond to environmental changes after inflammation, such as pH changes, may be beneficial for treating periodontitis. This study aims to investigate the preclinical feasibility of using naringin, a naturally derived polymethoxylated flavonoid compound with anti-inflammatory properties, to inhibit periodontitis induction via a thermogelling and pH-responsive injectable hydrogel. Methods: The hydrogel was made of amphipathic carboxy-methyl-hexanoyl chitosan (CHC), beta-glycerol phosphate (beta-GP), and glycerol. Thermogelling and pH-responsive characteristics of the hydrogel, as well as cell viability after treatment with the hydrogel containing naringin, were evaluated in vitro. Hydrogel was subgingivally delivered when experimental periodontitis was induced in vivo, and therapeutic effect was evaluated with microcomputed tomography imaging, histology, and expression of inflammation-associated genes, including toll-like receptor (TLR) 2, the receptor for advanced glycation end products (RAGE), myeloid differentiation primary response gene-88, and tumor necrosis factor (TNF)-alpha. Results: The hydrogel was consistently fluidic at 4 degrees C but rapidly gelled at 37 degrees C. Release of naringin was faster at pH 5.5 to 6.5, and viability was significantly promoted by treatment with 0.85% naringin. Naringin-carrying CHC-beta-GP-glycerol hydrogel sites showed significantly reduced periodontal bone loss (P < 0.05) and inflammatory infiltration (P < 0.01) as well as significantly downregulated TLR2 (P < 0.05), RAGE (P < 0.01), and TNF-alpha (P < 0.05) relative to the sites with experimental periodontitis alone. Conclusion: Naringin-carrying CHC-beta-GP-glycerol colloidal hydrogel can be used to inhibit induction of experimental periodontitis with favorable handling and inflammation-responsive characteristics.
Normally-OFF GaN MIS-HEMT With F- Doped Gate Insulator Using Standard Ion Implantation
(2018-01-01)
Wu, Chia-Hsun
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Han, Ping-Cheng
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Quang Ho Luc
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Hsu, Ching-Yi
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Hsieh, Ting-En
A normally-OFF GaN metal-insulator-gate high electron mobility transistors with fluorine doped gate insulator has been fabricated using standard ion implantation technique. Fluorine ions with negative charges were doped lightly into both the gate insulator and the partially recessed barrier layer, resulting in high positive threshold voltage (V-th) for the device, meanwhile preserving low ON-resistance. Compared to the fluorine-free and recess-free device, only about 16% increase of ON-resistance was observed for the F- doped devices. The fabricated F- doped device exhibits a threshold voltage of +0.68 V at I-Ds = 5 mu A/mm, a current density of 620 mA/mm, an OFF-state breakdown voltage of 800 V, and high ON/OFF current ratio of 10(10). For thermal stability consideration of fluorine dopant, the V-th-thermal stability test and positive bias temperature instability test were also discussed.
Normally-Off Tri-Gate GaN MIS-HEMTs with 0.76 m Omega center dot cm(2) Specific On-Resistance for Power Device Applications
(2019-08-01)
Wu, Chia-Hsun
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Chen, Jian-You
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Han, Ping-Cheng
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Lee, Ming-Wen
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Yang, Kun-Sheng
A GaN metal-insulator-semiconductor high electronmobility transistor (MIS-HEMT) using tri-gate architecture and hybrid ferroelectric charge trap gate stack is demonstrated for normally-off operation. Compared with the conventional planar device, the tri-gate device has the 2-D electron gas (2-DEG) channel exposed on the nanowire sidewalls, so that the trapped charges in the HfON charge-trapping layer can easily deplete the channel from the sidewalls, leading to a high positive threshold voltage (V-th) to realize the normally-off operation. Moreover, through this electrostatic control on the sidewall, a high density of negative charge caused by hybrid ferroelectric charge trap gate stack with the optimized tri-gate structure, the tri-gate device can achieve normally-off GaN device with both low on-resistance (R-ON) and high positive V-th. The designed tri-gate device exhibits a high V-th of +2.61 V at current density (I-DS) = 1 mu A/mm, a high maximum current density (I-DS, MAX) of 896 mA/mm, a low R-ON of 5.0 Omega center dot mm and a high breakdown voltage (BV) of 788 V. To the best of our knowledge, the proposed tri-gate device shows the lowest specific on-resistance (R-ON,R- SP) among reported normallyoff GaN device results with BV > 650 V.
pH-Responsive Hydrogel With an Anti-Glycation Agent for Modulating Experimental Periodontitis
(2016-06)
Yu, Min-Chen
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Chang, Chih-Yeun
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Chao, Yi-Chi
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Jheng, Yi-Han
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Yang, Connie
Background: Stimulus-responsive devices have emerged as a novel approach for local drug delivery. This study investigates the feasibility of a novel chitosan-based, pH-responsive hydrogel loaded with N-phenacylthiazolium bromide (PTB), which cleaves the crosslinks of advanced glycation end products on the extracellular matrix. Methods: A chitosan-based hydrogel loaded with PTB was fabricated, and the in vitro release profile was evaluated within pH 5.5 to 7.4. BALB/cJ mice and Sprague-Dawley rats were used to evaluate the effects during the induction and recovery phases of periodontitis, respectively, and animals in each phase were divided into four groups: 1) no periodontitis induction; 2) ligature-induced experimental periodontitis (group PR); 3) experimental periodontitis plus hydrogel without PTB (group PH); and 4) experimental periodontitis plus hydrogel with PTB (group PP). The therapeutic effects were evaluated by micro-computed tomographic imaging of periodontal bone level (PBL) loss and histomorphometry for inflammatory cell infiltration and collagen density. Results: PTB was released faster at pH 5.5 to 6.5 and consistently slower at pH 7.4. In the induction phase, PBL and inflammatory cell infiltration were significantly reduced in group PP relative to group PR, and the loss of collagen matrix was significantly reduced relative to that observed in group PH. In the recovery phase, PBL and inflammatory cell infiltration were significantly reduced, and significantly greater collagen deposition was noted in group PP relative to groups PR and PH at 4 and 14 days after silk removal. Conclusion: Chitosan-based, pH-responsive hydrogels loaded with PTB can retard the initiation of and facilitate the recovery from experimental periodontitis.
Reconfigurable Vertical Profiling Framework for the Android Runtime System
(2014-01-01)
Su, Tzu-Hsiang
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Tsai, Hsiang-Jen
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Yang, Keng-Hao
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Chang, Po-Chun
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Chen, Tien-Fu
Dalvik virtual machine in the Android system creates a profiling barrier between VM-space applications and Linux user-space libraries. It is difficult for existing profiling tools on the Android system to definitively identify whether a bottleneck occurred in the application level, the Linux user-space level, or the Linux kernel level. Information barriers exist between VM-space applications and Linux native analysis tools due to runtime virtual machines' dynamic memory allocation mechanism. Furthermore, traditional vertical profiling tools targeted for Java virtual machines cannot be simply applied on the Dalvik virtual machine due to its unique design. The proposed the Reconfigurable Vertical Profiling Framework bridges the information gap and streamlines the hardware-software co-design process for the Android runtime system.
STUDY ON THE ELECTRICAL CHARACTERISTICS OF IN SITU PEALD-PASSIVATED HFO2/IN(0.53)GA(0.47)AS MOSCAP AND MOSFET STRUCTURES
(2016)
Luc, Quang-Ho
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Chang, Po-Chun
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Do, Huy-Binh
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Lin, Yueh-Chin
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Chang, Edward Yi
In situ PEALD processes, including PEALD-A1N pre-gate and post-gate plasma gas treatments, have been studied as a promising passivation method to realize the high interfacial quality of high-k/III-V structures. The formation of excellent dielectric gate stack has been obtained on the HfO2/n, p-In0.53Ga0.47As MOSCAPs by inserting an A1N interfacial layer. The improvements on the electrical properties of HfO2/In0.53Ga0.47As nMOSFET such as maximum drain current, subthreshold swing, off leakage current, and effective electron mobility have been achieved. Utilizing low frequency noise, charge pumping, and bias temperature instability stress technologies, the reliability of the in situ PEALD-passivated HfO2/In0.53Ga0.47As nMOSFET is evaluated.