Browsing by Author "Chen, Chu-Feng"

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ANNEALING TEMPERATURE EFFECT ON THE SENSITIVITY OF SIGE NANOWIRE FOR BIO-SENSOR
(2011)
Chang, Kow-Ming
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Chen, Chu-Feng
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Wang, Yu-Bin
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Liu, Chung-Hsien
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Kuo, Jiun-Ming
Nanowire is widely used in biological sensor because it has the high surface-to-volume ratio. Germanium (Ge) would be beneficial to enhance the sensitivity of silicon nanowire for bio-sensor. In this study, we have successfully fabricated the SiGe on Insulator (SGOI) nanowires with different annealing temperature by side-wall spacer technique, respectively. The 3-amino-propyltrime-thoxy-silane (APTS) is used to modify the surface, which can connect the bio-linker. Nanowire is considered as a resistance, and the change of conductance (Delta G) and sensitivity (S) of different samples corresponding to APTS treatment were investigated. As annealing temperature was elevated from 800 to 950 degrees C, the SiGe nanowire exhibited increasing sensitivity in the chemical detection. However, it was noted that degradation of sensitivity was observed as the annealing temperature increases up to 1000 degrees C. This behavior may be associated with the reduction of the Ge concentration at the surface of SiGe nanowire due to high-temperature diffusion of Ge in Si. So, temperature is a key parameter in the annealing process producing two effects: repairs of defects and Ge diffusion. There would be an optimal annealing temperature between 900 and 1000 degrees C.
EFFECT OF THE MIXED N-2/O-2 OXIDATION PROCESS ON IMPROVEMENT OF THE SENSITIVITY OF THE SIGE NANO-WIRE
(2011-01-01)
Chang, Kow-Ming
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Chen, Chu-Feng
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Lai, Chiung-Hui
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Wang, Yu-Bin
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Liu, Chung-Hsien
Ge condensation has been reported to improve the hole mobility of the SiGe-on-insulator (SGOI). Our previous studies have shown that the higher Ge fraction of Si1-xGex nano-wire exhibits higher sensitivity. In this work, we investigated the effect of different oxidation recipe to provide information on the sensitivity of SiGe nano-wire. The 3-amino-propyltrime-thoxy-silane (APTMS) is used to modify the nano-wire's surface potential. Induced sensitivity characteristics of the samples were preformed to estimate the improvement effect. The mixed N-2/O-2 oxidation process with optimization ratio can be an effective technology to improve the sensitivity of SGOI nano-wires.
Effects of low-temperature Si buffer thickness and SiGe oxidation on sensitivity of Si1-xGex nanowire
(2015-06-01)
Lai, Yi-Lung
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Chang, Tai-Yuan
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Chang, Kow-Ming
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Chen, Chu-Feng
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Lai, Chiung-Hui
Si1-xGex nanowire biosensors are attractive for their high sensitivity due to the large surface-to-volume ratio, high carrier mobility, and silicon compatibility. In this work, we study the effect of the thickness of the low-temperature Si (LT-Si) buffer layer on an insulator on the sensitivity of oxidized Si1-xGex nanowire samples with different Ge contents by increasing the Si buffer thickness from 20 to 60 nm. 3-Aminopropyltrimethoxy-silane (APTMS) was used as a biochemical reagent. It was demonstrated that, with the proper Ge content and LT-Si buffer thickness, the sensitivity of the Si1-xGex nanowire is high and it can be further improved by Si1-xGex oxidation. This can be attributed to the reduction of the diameter to the nanometer order, which gives rise to an increased surface-to-volume ratio and further enhances the sensitivity of the biosensor. (C) 2015 The Japan Society of Applied Physics
Electrical properties of SiGe nanowire following fluorine/nitrogen plasma treatment
(2014-01-15)
Chang, Kow-Ming
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Chen, Chu-Feng
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Lai, Chiung-Hui
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Kuo, Po-Shen
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Chen, Yi-Ming
The improvements to electrical properties of SiGe nanowires by surface plasma treatment were investigated. Various durations of pre-oxidation with fluorine; ambients for post-nitridation plasma treatment, and annealing temperature after plasma treatment, 800-950 degrees C, were applied. Pre-oxidation treatment using fluorine plasma; improved the conductance of SiGe nanowires because the Si-F binding energy created a more stable interface state than bare nanowire on the surface of SiGe. N-2 plasma incorporated more N than does in NH3 plasma, and NH3 has the drawback of introducing electron traps, causing Si-H bonds to break in the subsequent annealing process. Since the reparation of surface defects by plasma treatment is valid, the high post-annealing temperature to reduce defect by re-crystallizing can be reduced. Hence, Ge diffusion at low post-annealing temperature did not reduce the high concentration of Ge at the SiGe nanowire surfaces. (C) 2013 Elsevier B.V. All rights reserved.
Influence of Surface State on Biochemical Sensing Using SiGe Nanowire
(2015-06-01)
Lai, Chiung-Hui
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Chang, Kow-Ming
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Chen, Yi-Ming
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Chen, Chu-Feng
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Kuo, Po-Shen
Nanowires are extensively used to fabricate highly sensitive electrical sensors for detection of biological and chemical species. The hole mobility can be promoted by the increasing Ge fraction in SiGe, achieved by the oxidation-induced Ge condensation. However, oxidation increases the number of surface states, which brings the nonnegligible contribution in mobility degradation. In this work, 3-aminopropyltrimethoxysilane (APTMS) was used as a biochemical reagent to modify the surface of SiGe nanowires, then bonding to bio-linker, bis (3-sulfo-N-hydroxysuccinimide ester) sodium salt (BS3). Various methods have been proposed for increasing sensitivity of boron-doped SiGe nanowires, such as capping layer, surface treatment, and annealing temperature.
Investigation of Defect Free SiGe Nanowire Biosensor Modified by Dual Plasma Technology
(2016-02)
Chen, Yi-Ming
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Chang, Tai-Yuan
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Lai, Chiung-Hui
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Chang, Kow-Ming
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Chen, Chu-Feng
Semiconductor nanowires (NWs) have been extensively investigated and discussed in various fields due to their unique physical properties. In this paper, we successfully produce SiGe NWs biosensor by VLSI technology. We propose the dual plasma technology with CF4 plasma pre-treatment and N-2 plasma post-treatment for repairs of defects as well as optimization of SiGe NWs biosensor. The results indicate that sensitivity (S) of the biosensor with dual plasma technology has significantly improved at least 32.8%, suitable for producing industrial SiGe NWs biosensor in the future.
OXIDATION STUDY OF GE CONDENSATION ON SGOI NANOWIRE BIOSENSOR FABRICATION
(2013-01-01)
Chang, Kow-Ming
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Chen, Chu-Feng
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Lai, Chiung-Hui
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Wu, Chin-Ning
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Hsieh, Cheng-Ting
The Ge condensation method is effective in increasing the Ge fraction of Ge in SGOI. Previous studies by the authors confirmed a correlation between the Ge fraction and the sensitivity of the SiGe nano-wire sensor. To understand how Ge condensation on an SGOI nano-wire sensor helps to optimize oxidation conditions and sensitivity, the effect of oxidizing gas and the SiGe/alpha-Si stacked structure on the movement of Ge is investigated. The analytical results reveal that the sensitivity of SiGe nano-wires can be optimized by stacking an Si1-xGex layer that contains 14% Ge on a 200 angstrom-thick alpha-Si layer and treating the stack with O-2 gas diluted by 13% N-2 for 3 min.
Sensitivity enhancement in SiGe-on-insulator nanowire biosensor fabricated by top surface passivation
(2012-08-01)
Lai, Chiung-Hui
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Chang, Kow-Ming
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Chen, Chu-Feng
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Hsieh, Cheng-Ting
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Wu, Chin-Ning
The oxidation caused by Ge condensation increases the Ge fraction in a SiGe-on-insulator (SGOI) and significantly increases the hole mobility. This effect can be exploited to improve the sensitivity of SGOI nanowires. However, previous studies have found that the sensitivity of SGOI nanowires degrades when the Ge fraction exceeds 20%, because a high Ge fraction destabilises the surface state of SiGe. In this work, a top surface passivation plasma-enhanced chemical vapour deposition SiO2 layer deposited on a Si0.8Ge0.2 nanowire improved its sensitivity by similar to 1.3 times that of the nanowire sample without a top passivation layer.
SURFACE PASSIVATION EFFECT IN SGOI NANOWIRE BIOSENSOR WITH HIGH GE FRACTION
(2012-01-01)
Chang, Kow-Ming
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Chen, Chu-Feng
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Lai, Chiung-Hui
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Hsieh, Cheng-Ting
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Wu, Chin-Ning
The increase of surface to volume ratio results in the enhancement of the sensitivity of the nanowires. Our previous studies have shown that the higher Ge fraction of Si1-xGex nano-wire improves the sensitivity of the nanowire biosensor as a result of carrier mobility enhancement in strain-Si. Increasing the fraction of Ge in SiGe-on-Insulator (SGOI) using Ge condensation by oxidation has obtained a significant enhancement in hole mobility, further improving the sensitivity of SGOI nanowire. However, the sensitivity of SGOI nanowire was degraded for exceeding a Ge fraction of 20% (i.e., high Ge fraction), resulting from the unstable surface state. In this work, a top surface passivation SiO2 layer was deposited on Si0.8Ge0.2 nanowire and the sensitivity was about 1.3 times greater than nanowire sample without the top passivation layer.
The alpha-Si/SiGe core/shell nano-wire as highly sensitive bio-sensor
(2011-01-01)
Chang, Kow-Ming
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Chen, Chu-Feng
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Lai, Chiung-Hui
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Liu, Chung-Hsien
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Wang, Yu-Bin
Reducing the width of a nano-wire increases its surface to volume ratio, increasing the sensitivity of its conductivity to charges on its surface. Our previous studies have shown that increasing the Ge fraction in Si1-xGex nano-wires improves their sensitivity as bio-sensing. In this work, an alpha-Si/SiGe core/shell nano-wire is successfully fabricated using side-wall spacer method. The maximum sensitivity of a nano-wire bio-sensor with an optimized alpha-Si/SiGe thickness ratio is investigated.