Browsing by Author "Lu, Ming-Pei"

Now showing 1 - 7 of 7

Gas Sensing Ability on Polycrystalline-Silicon Nanowire
(2018-01-01)
Lo, Yen-Ren
;
Chen, Huang-Ming Philip
;
Yang, Yuh-Shyong
;
Lu, Ming-Pei
;
生物科技學系
Trace of protic gases can alter the conductivity of the polycrystalline silicon nanowire (poly-Si NW) field effect transistor (FET). The aprotic gases have no effect on the electrical parameters. The proposed mechanism is due to the surface grain boundary of poly-Si NW. The direct evidence is obtained from the comparison between single-and poly-Si NW. The electrical parameters are varied according to the relative humidity levels. Nevertheless, the water molecules can be removed by vacuum indicating that it is physical absorption on the surface. As a result, the poly-Si NW FET has potential to be a reusable device for protic gas sensor. (C) The Author(s) 2018. Published by ECS.
Influences of Contact Metals on the Performances of MoS2 Devices under Strains
(2019-12-19)
Tseng, Sian-Hong
;
Chen, Hung-Yi
;
Hsu, Wei-Ting
;
Wang, Hsiang-Chen
;
Li, Yuan-Yao
The growth of large-area MoS2 films was achieved through atmospheric pressure chemical vapor deposition via vapor management in this study. The thickness of the MoS2 film changed upon varying the amount of vapor deposited on the substrate. Gratifyingly, large-area monolayer MoS2 was obtained under controlled conditions. Studies using transmission electron microscopy and second harmonic generation confirmed that the MoS2 films were composed of grains having sizes ranging from 40 to 70 mu m. Flexible MoS2 device arrays were fabricated on a polyimide substrate; the device arrays displayed high spatial uniformity in their carrier transport properties. The contact metals affected the electrical characteristics of the MoS2 devices under strain; the sensitivity of devices featuring Schottky contacts was higher than that of those with ohmic contacts. Importantly, the device arrays exhibit sensitive and endurance performances under strain cycles of up to 10(5) times. These results suggest a means for the feasible growth of large-area single-layer MoS2 films, as well as the exploitation of flexible MoS2 device arrays in strain and human motion sensor applications.
Intercrossed Sheet-Like Ga-Doped ZnS Nanostructures with Superb Photocatalytic Actvitiy and Photoresponse
(2009-07-23)
Lu, Ming-Yen
;
Lu, Ming-Pei
;
Chung, Yao-An
;
Chen, Ming-Jer
;
Wang, Zhong Lin
Intercrossed ZnS nanostructures doped with Ga (ZnS:Ga nanowalls) have been synthesized in high yield from mixed powders in a vacuum furnace. ZnS:Ga nanowalls were grown vertically on the substrate with the size in the range of several micrometers and the thickness down to similar to 15 nm and have very rough edges. Due to the high surface area and distinctive morphology of ZnS:Ga nanowalls, the photocatalytic activity and the photoresponse show superior properties compared to ZnS:Ga films. The increased conductivity of metal-semiconductor-metal (Ag-ZnS:Ga nanowalls-Ag) Schottky photodetectors under light illumination is attributed to the photogenerated electron-hole pairs, the desorption of oxygen molecules on the ZnS:Ga surface, and the lowering of the Schottky barrier height. The results indicate that ZnS:Ga nanowalls are promising candidate materials for photocatalysts and applicable as photodetectors, optical switches, and sensors in the visible light region.
Probing a nonuniform two-dimensional electron gas with random telegraph signals
(2008-02-01)
Chen, Ming-Jer
;
Lee, Chien-Chih
;
Lu, Ming-Pei
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
We observe a sequence of two-level random telegraph signals (RTSs) in the drain/source current of a 1.7 nm gate oxide silicon metal-oxide-semiconductor field-effect transistor. The RTS magnitude is transformed into the apparent Debye length around a negatively charged oxide trap. We achieve excellent reproduction of the Debye data (40 down to 5 nm). This leads to the quantified area spanned by the dominant conductive percolation paths in the underlying two-dimensional electron gas (2DEG). We find that most of the 2DEG in inversion is recovered in a largest threshold voltage sample (similar to 0.35 V), while for the lowest threshold (similar to 0.15 V), a certain conductive filament is likely to occur. The gate direct tunneling current further corroborates the percolation picture. (c) 2008 American Institute of Physics.
Probing the sensitivity of nanowire-based biosensors using liquid-gating
(2010-10-22)
Lu, Ming-Pei
;
Hsiao, Cheng-Yun
;
Lai, Wen-Tsan
;
Yang, Yuh-Shyong
;
生物科技學系
We have used liquid-gating to investigate the sensitivity of nanowire (NW)-based biosensors for application in the field of ultrasensitive biodetection. We developed an equivalent capacitance model of the biosensor system to explore the dependence of the sensitivity on the liquid-gate voltage (V(lg)), which was influenced by capacitive competition between the NW capacitance and the thin oxide capacitance. NW biosensors with highest sensitivity were obtained when we operated the device in the subthreshold regime while applying an appropriate value of Vlg; the influence of leakage paths through the ionic solutions led, however, to significant sensitivity degradation and narrowed the operating window in the subthreshold regime.
Surface composition and interactions of mobile charges with immobilized molecules on polycrystalline silicon nanowires
(2015-05-01)
Lin, Chih-Heng
;
Feng, Mei-Huei
;
Hwang, Chi-Hung
;
Wu, Jennifer Yun-Shin
;
Su, Ping-Chia
The polycrystalline silicon nanowire field-effect transistor (poly-SiNW FET) is one of the most sensitive sensors used in real-time and label-free biosensing applications. Its low power requirement, mass production potential, and integrability with electronic components make it a highly attractive device in the rapidly growing diagnostic research field. From the viewpoint of device physics, the charges in the vicinity of a nanowire (NW) surface modulate the electrical characteristics of the NW device. The charges can originate from surface molecules or an ionic solution, and their role in NW biosensing systems remains to be clarified. Determining their role is crucial for understanding the physical interactions of charges in a biosensing event and for the realization of NW-based biosensors. Therefore, using poly-SiNW FET, we investigated the interactions of the immobilized molecules on the NW surface with the mobile charges in solutions. We also investigated the interactions between the mobile charged polymers and the immobilized molecules on the NW surface, and we observed the effect of charge neutrality, originating from Coulomb charge-charge interactions, on the NW conductance. Finally, the isoelectric points between native and sulfated PSGL-1 peptides on the NW surface were identified. This study provides a physical understanding of the charge-charge interaction of mobile charges with immobilized charged molecules on a nanoscale surface and presents new opportunities for using charge-based detection in biological and chemical sensing applications. (C) 2015 Elsevier B.V. All rights reserved.
Vertically well-aligned epitaxial Ni(31)Si(12) nanowire arrays with excellent field emission properties
(2008-09-15)
Lee, Chung-Yang
;
Lu, Ming-Pei
;
Liao, Kao-Feng
;
Wu, Wen-Wei
;
Chen, Lih-Juann
Vertically well-aligned single crystal Ni(31)Si(12) nanowire (NW) arrays were epitaxially grown on Ni(31)Si(12) films preferentially formed on Ni foil substrates with a simple vapor phase deposition method in one step. The Ni(31)Si(12) NWs are several micrometers in length and 50-80 nm in diameter. The resistivities of the Ni(31)Si(12) NWs were measured to be 51 mu Omega cm by four-terminal electrical measurement. The NWs can carry very high currents and possess excellent field emission properties. The growth of vertically well-aligned Ni(31)Si(12) NW arrays shall lead to significant advantages in the fabrication of vertical Si nanodevices. (C) 2008 American Institute of Physics.