Browsing by Author "Cheng, C. H."

Now showing 1 - 20 of 72

A facile method to prepare "green" nano-phosphors with a large Stokes-shift and solid-state enhanced photophysical properties based on surface-modified gold nanoclusters
(2017-12-15)
Cheng, C. H.
;
Huang, H. Y.
;
Talite, M. J.
;
Chou, W. C.
;
Yeh, J. M.
Colloidal nano-materials, such as quantum dots (QDs) have been applied to light-conversion nano phosphors due to their unique tunable emission. However, most of the QDs involve toxic elements and are synthesized in a hazardous solvent. In addition, conventional QD nano-phosphors with a small Stokes shift suffered from reabsorption losses and aggregation-induced quenching in the solid state. Here, we demonstrate a facile, matrix-free method to prepare eco-friendly nano-phosphors with a large Stokes shift based on aqueous thiolate-stabilized gold nanoclusters (GSH-AuNCs) with simple surface modifications. Our method is just to drop GSH-AuNCs solution on the aluminum foil and then surface modified AuNCs (Al-GSH-AuNCs) can be spontaneously precipitated out of the aqueous solution. Compared with pristine GSH-AuNCs in solution, the Al-GSH-AuNCs exhibit enhanced solid-state PL quantum yields, lengthened PL lifetime, and spectral blue shift, which can be attributed to the aggregation induced emission enhancement facilitated by surface modifications. Such surface-treatment induced aggregation of AuNCs can restrict the surface-ligand motion, leading to the enhancement of PL properties in the solid state. In addition, the Al-GSH-AuNCs nano-phosphors with a large Stokes shift can mitigate the aggregation-induced PL quenching and reabsorption losses, which would be potential candidates for "green" nano-phosphors. (C) 2017 Elsevier Inc. All rights reserved.
A Study on Frequency-Dependent Voltage Nonlinearity of SrTiO(3) rf Capacitor
(2010-01-01)
Cheng, C. H.
;
Huang, C. C.
;
Hsu, H. H.
;
Chen, P. C.
;
Chiang, K. C.
In this article, we investigate the frequency-dependent voltage nonlinearity effect of high-kappa Ni/SrTiO(3)/TaN and TaN/SrTiO(3)/TaN radio-frequency (rf) metal-insulator-metal (MIM) capacitors by electrical and thermal stresses. The experimental results demonstrated that the MIM-related capacitance properties, dependence of voltage and frequency, are not only affected by intrinsic dielectric properties but also shared by extrinsic effect, which possibly originated from the oxygen vacancies or electrode polarization. The high work-function Ni electrode can prevent the frequency-dependent voltage coefficient of capacitance characteristics from deterioration under the high temperature or continued voltage-stressing environments. (C) 2010 The Electrochemical Society. [DOI: 10.1149/1.3491490] All rights reserved.
A Study on Frequency-Dependent Voltage Nonlinearity of SrTiO3 rf Capacitor
(2010-01-01)
Cheng, C. H.
;
Huang, C. C.
;
Hsu, H. H.
;
Chen, P. C.
;
Chiang, K. C.
In this article, we investigate the frequency-dependent voltage nonlinearity effect of high-kappa Ni/SrTiO3/TaN and TaN/SrTiO3/TaN radio-frequency (rf) metal-insulator-metal (MIM) capacitors by electrical and thermal stresses. The experimental results demonstrated that the MIM-related capacitance properties, dependence of voltage and frequency, are not only affected by intrinsic dielectric properties but also shared by extrinsic effect, which possibly originated from the oxygen vacancies or electrode polarization. The high work-function Ni electrode can prevent the frequency-dependent voltage coefficient of capacitance characteristics from deterioration under the high temperature or continued voltage-stressing environments. (C) 2010 The Electrochemical Society. [DOI: 10.1149/1.3491490] All rights reserved.
Achieving low sub-0.6-nm EOT in gate-first n-MOSFET with TiLaO/CeO2 gate stack
(2013-04-01)
Cheng, C. H.
;
Chou, K. I.
;
Chin, Albert
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
We report a gate-first TiLaO/CeO2 n-MOSFET with an equivalent oxide thickness (EOT) of only 0.56 nm and threshold voltage (V-t) of 0.31 V. This small EOT MOSFET was achieved by employing high-kappa CeO2 interfacial layer with high bond enthalpy (795 kJ/mol) to replace low-kappa SiO2 with close bond enthalpy (800 kJ/mol). The cerium silicate can aggressively scale EOT down to sub-0.6-nm EOT region without increasing gate leakage, which is urgently needed for 16 nm technology node. (C) 2013 Elsevier Ltd. All rights reserved.
An analytical solution for transport of oxygen in cathode gas diffusion layer of PEMFC
(2006-09-29)
Tsai, C. R.
;
Chen, Falin
;
Ruo, A. C.
;
Chang, Min-Hsing
;
Chu, Hsin-Sen
A two-dimensional theoretical model is developed in this study to simulate the transport phenomena of oxygen in cathode gas diffusion layer (GDL) of proton exchange membrane fuel cell (PEMFC). An analytical solution is then obtained accordingly to characterize the effects of GDL on cell performance. It is found that the concentration flux of oxygen across the GDL is primarily dominated by the thickness and porosity of GDL. For a thicker GDL, the diffusion resistance increases and thus lowers the cell performance especially under high current density condition. On the other hand, an increase of porosity will enhance the transport of oxygen and result in significant improvement of cell performance. The influences of system parameters including the temperature, channel height, inlet velocity, and inlet pressure on the diffusion of oxygen in GDL are also examined systematically. Results provide insights into the characteristics of oxygen diffusion in GDL and benefit the optimal design of PEMFC. (c) 2006 Elsevier B.V. All rights reserved.
Bipolar conductivity in amorphous HfO(2)
(2011-08-15)
Islamov, D. R.
;
Gritsenko, V. A.
;
Cheng, C. H.
;
Chin, A.
;
交大名義發表
This study calculates the contribution of electrons and holes to HfO(2) conductivity in Si/HfO(2)/Ni structures using experiments on injection of minority carriers from n- and p-type silicon. Results show that electrons and holes contribute to the conductivity of HfO(2), allowing HfO(2) to exhibit two-band conductivity. (C) 2011 American Institute of Physics. [doi:10.1063/1.3626599]
Bipolar conductivity in amorphous HfO2
(2011-08-15)
Islamov, D. R.
;
Gritsenko, V. A.
;
Cheng, C. H.
;
Chin, A.
;
交大名義發表
This study calculates the contribution of electrons and holes to HfO2 conductivity in Si/HfO2/Ni structures using experiments on injection of minority carriers from n- and p-type silicon. Results show that electrons and holes contribute to the conductivity of HfO2, allowing HfO2 to exhibit two-band conductivity. (C) 2011 American Institute of Physics. [doi:10.1063/1.3626599]
Bipolar conductivity in nanocrystallized TiO2
(1970-01-01)
Islamov, D. R.
;
Gritsenko, V. A.
;
Cheng, C. H.
;
Chin, A.
;
交大名義發表
"This study calculated the contribution of electrons and holes to TiO2 conductivity in Si/TiO2/Ni structures by conducting experiments on the injection of minority carriers from n- and p-type silicon. Results show that electrons and holes contribute to the conductivity of TiO2, enabling two-band conductivity. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4737016]"
Bipolar switching characteristics of low-power Geo resistive memory
(2011-08-01)
Cheng, C. H.
;
Chen, P. C.
;
Liu, S. L.
;
Wu, T. L.
;
Hsu, H. H.
We reported an ultra low-power resistive random access memory (RRAM) combining a low-cost Ni electrode and covalent-bond GeO(x) dielectric. This cost-effective Ni/GeO(x)/TaN RRAM device has very small set power of 2 mu W, ultra-low reset power of 130 pW, greater than 1 order of magnitude resistance window, and stable retention at 85 degrees C. The current flow at low-resistance state is governed by Poole-Frenkel conduction with electrons hopping via defect traps, which is quite different from the filament conduction in metal-oxide RRAM. (C) 2011 Elsevier Ltd. All rights reserved.
Channel Modification Engineering by Plasma Processing in Tin-Oxide Thin Film Transistor: Experimental Results and First-Principles Calculation
(2017-01-01)
Chiu, Y. C.
;
Chen, P. C.
;
Chang, S. L.
;
Zheng, Z. W.
;
Cheng, C. H.
In this paper, we investigated the effects of oxygen plasma treatment on tin oxide (SnOx) thin film transistors (TFTs). By using oxygen plasma treatment on SnOx active channel layer, excess oxygen was incorporated to the channel layer and converted oxygen-deficient SnOx to oxygen-rich SnO2-x, which in turn causes the device operation from p-type to n-type. Tuning the different exposure time of oxygen plasma, the optimal TFT device exhibits n-type properties with an on/off current ratio of 2.6 x 10(4), a very high field-effect mobility of 89 cm(2) V-1 s(-1), and a threshold voltage of -0.95 V. Furthermore, the effects of oxygen plasma treatment on band structure, density of states and electron density difference of the SnOx channel layer were performed by the first-principles calculation using density functional theory. The results show that the oxygen plasma treatment approach has high potential for high-performance TFT applications. (C) 2017 The Electrochemical Society. All rights reserved.
Characteristics of Cerium Oxide for Metal-Insulator-Metal Capacitors
(2010)
Cheng, C. H.
;
Hsu, H. H.
;
Chen, W. B.
;
Chin, Albert
;
Yeh, F. S.
In this article, we describe our successful fabrication of a CeO(2) metal-insulator-metal (MIM) capacitor with a low voltage nonlinearity. A low leakage current of 3.9 X 10(-7) A/cm(2) at -1 V and a small VCC-alpha similar to 421 ppm/V(2) were obtained at a high 10.8 fF/mu m(2) density for a Pt/CeO(2)/TaN MIM capacitor. The small VCC-alpha for a 15 nm thick CeO(2) dielectric (kappa similar to 20) was much better than the reported dielectrics of HfO(2), Tb-HfO(2), and Al(2)O(3)-HfO(2) at a similar kappa-value (15-20). The good analog performance was due to the combined effect of the CeO(2) dielectric and the high work-function metals. (C) 2009 The Electrochemical Society. [DOI: 10.1149/1.3258042] All rights reserved.
Charge transport in amorphous Hf0.5Zr0.5O2
(2015-03-09)
Islamov, D. R.
;
Perevalov, T. V.
;
Gritsenko, V. A.
;
Cheng, C. H.
;
Chin, A.
In this study, we demonstrated experimentally and theoretically that the charge transport mechanism in amorphous Hf0.5Zr0.5O2 is phonon-assisted tunneling between traps like in HfO2 and ZrO2. The thermal trap energy of 1.25 eV and optical trap energy of 2.5 eV in Hf0.5Zr0.5O2 were determined based on comparison of experimental data on transport with different theories of charge transfer in dielectrics. A hypothesis that oxygen vacancies are responsible for the charge transport in Hf0.5Zr0.5O2 was discussed. (C) 2015 AIP Publishing LLC.
Chip-Level Characterization and RTN-Induced Error Mitigation beyond 20nm Floating Gate Flash Memory
(2018-01-01)
Lin, T. W.
;
Ku, S. H.
;
Cheng, C. H.
;
Lee, C. W.
;
Ijen-Huang
Vt instability caused by random telegraph noise (RTN) in floating gate flash memories beyond 20nm is studied comprehensively. Experiments reveal that the RTN would cause Vt distribution with a kinked tail which re-distributes to a "Gaussian-like" shape rapidly and was measured by the self established Budget Product Tester (BPT). A Multi-Times Verify (MTV) algorithm to mitigate the statistical tail, thus enlarging operation window is also exhibited by BPT. In further, a probability model to portray the compact Vt distribution under MTV is proposed. Finally, the impact of MTV on lowering the requirement of Error-correcting code (ECC) bit is also demonstrated.
Electrical instability of InGaZnO thin-film transistors with and without titanium sub-oxide layer under light illumination
(2017-03-01)
Chiu, Y. C.
;
Zheng, Z. W.
;
Cheng, C. H.
;
Chen, P. C.
;
Yen, S. S.
The electrical instability behaviors of amorphous indium-gallium-zinc oxide thin-film transistors with and without titanium sub-oxide passivation layer were investigated under light illumination in this study. For the unpassivated IGZO TFT device, in contrast with the dark case, a noticeable increase of the sub-threshold swing was observed when under the illumination environment, which can be attributed to the generation of ionized oxygen vacancies within the alpha-IGZO active layer by high energy photons. For the passivated TFT device, the much smaller SS of similar to 70 mV/dec and high device mobility of >100 cm(2)/Vs at a drive voltage of 3 V with negligible degradation under light illumination are achieved due to the passivation effect of n-type titanium sub-oxide semiconductor, which may create potential application for high-performance display.
Error Characterization and ECC Usage Relaxation beyond 20nm Floating Gate NAND Flash Memory
(2018-01-01)
Ku, S. H.
;
Lin, T. W.
;
Cheng, C. H.
;
Lee, C. W.
;
Chen, Ti-Wen
Endurance of floating gate flash memories at 19nm node and beyond is studied comprehensively. Experiments reveal that the random telegraph noise (RTN) would degrade the read margin with a tail, which quickly reshapes into a symmetric Gaussian form in a lightly-stressed state. After heavy stress, the lower part of tail would spread further while the upper part keeps roughly overlapped with that during fresh. This unique behavior, which was firstly measured by the self-established Budget Product Tester (BPT), can be explained by stress-induced hole trap creation. To investigate the impact of RTN on operation window, a novel algorithm of Multi-Times-Verify accompanied with the optimal Read-Retry (MTVR2) is proposed and validated by BPT. The advantage of MTVR2 to reduce the requirement of Error-Correcting Code (ECC) bit is demonstrated. Finally, the improvement of bit error rate (BER) in TLC operation with MTVR(2 )is also evaluated.
Evolution of the conductivity type in germania by varying the stoichiometry
(2013-12-02)
Islamov, D. R.
;
Gritsenko, V. A.
;
Cheng, C. H.
;
Chin, A.
;
交大名義發表
Information regarding the conductivity type of Si/GeOx/Ni structures with various stoichiometry has been obtained using experiments on injection of minority carriers from n- and p-type silicon. Results show that non-stoichiometric GeOx films exhibit bipolar conductivity, that is, holes as well as electrons contribute to the charge transport. Stoichiometric GeO2 films exhibit unipolar electron conductivity. (C) 2013 AIP Publishing LLC.
Flow Rate's Influence on Low Temperature Silicon Oxide Deposited by Atmospheric Pressure Plasma Jet for Organic Thin Film Transistor Application
(2010)
Chang, K. M.
;
Huang, S. S.
;
Cheng, C. H.
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
Low temperature processes and high quality gate insulator are very important for organic thin film transistors (OTFTs). We utilized atmospheric pressure plasma jet (APPJ) to deposit silicon oxide as gate insulator of OTFTs at low temperature. We found carrier gas's flow rate would influence the deposition mechanism which lead to influence surface roughness and film quality. Leakage current density of our proposed silicon oxide was about 2.53E-8 A/cm(2) at 0.5 MV/cm. Our proposed OTFTs shows a low subthreshold swing of only 700 mV/dec., a low threshold voltage of -0.8 V, a low operation voltage of -2 V. The low-voltage OTFTs would reduce the power consummation of flexible display.
Gate-first n-MOSFET with a sub-0.6-nm EOT gate stack
(2013-09-01)
Cheng, C. H.
;
Chou, K. I.
;
Chin, A.
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
We report a self-aligned and gate-first TiLaO/La2O3 n-MOSFET with an equivalent oxide thickness (EOT) of 0.57 nm and low threshold voltage (V-t) of 0.3 V. The small EOT MOSFET can be reached using La-based interfacial layer with strong bond enthalpy (La-O, 799 kJ/mol) to suppress the formation of defect-rich low- interfacial layer and simultaneously block titanium atom inter-diffusion to avoid additional EOT increase. This gate-first low-EOT MOSFET exhibits the potential to integrate with current CMOS process. (C) 2013 Elsevier B.V. All rights reserved.
High Capacitance Density and Thermal Leakage Improvement by Using High-kappa Al(2)O(3)-Doped SrTiO(3) MIM Capacitors
(2010-01-01)
Huang, C. C.
;
Cheng, C. H.
;
Lin, C. W.
;
Chang, L. M.
;
電子工程學系及電子研究所
In this paper, the impact of Al(2)O(3) incorporation on the electrical characteristics of the SrTiO(3) (STO) metal-insulator-insulator (MIM) capacitor was studied. The Al(2)O(3)-doped STO (STO: Al(2)O(3) = 3:1) MIM provides a high capacitance density (14.6 fF/mu m(2)) and a very low leakage current density (9.2 x 10(-9) A/cm(2) at -1 V) at the same time. The significant enhancement of the conduction band offset and bandgap due to Al(2)O(3) incorporation reduces leakage current largely while maintaining the favorable properties of STO, such as a large high-kappa value, a small temperature coefficient of capacitance, and paraelectricity (no fatigue or aging problem) in the operating temperature range of devices. Meanwhile, we also made a comparison among pure STO, Al(2)O(3)-doped STO, and HfO(2)-doped STO MIM capacitors. Results revealed that STO MIM and HfO(2)-doped STO MIM capacitors both show higher capacitance densities, while the leakage current of the Al(2)O(3)-doped STO MIM is much lower than those of both the STO MIM and HfO(2)-doped STO MIM capacitors, which meets the strict requirement of the International Technology Roadmap for Semiconductors 2018. Therefore, the excellent result suggests that the Al(2)O(3)-doped STO film is a potential candidate material for dynamic random access memory and radio-frequency applications. (C) 2010 The Electrochemical Society. [DOI: 10.1149/1.3368671] All rights reserved.
High Capacitance Density and Thermal Leakage Improvement by Using High-kappa Al2O3-Doped SrTiO3 MIM Capacitors
(2010-01-01)
Huang, C. C.
;
Cheng, C. H.
;
Lin, C. W.
;
Chang, L. M.
;
電子工程學系及電子研究所
In this paper, the impact of Al2O3 incorporation on the electrical characteristics of the SrTiO3 (STO) metal-insulator-insulator (MIM) capacitor was studied. The Al2O3-doped STO (STO: Al2O3 = 3:1) MIM provides a high capacitance density (14.6 fF/mu m(2)) and a very low leakage current density (9.2 x 10(-9) A/cm(2) at -1 V) at the same time. The significant enhancement of the conduction band offset and bandgap due to Al2O3 incorporation reduces leakage current largely while maintaining the favorable properties of STO, such as a large high-kappa value, a small temperature coefficient of capacitance, and paraelectricity (no fatigue or aging problem) in the operating temperature range of devices. Meanwhile, we also made a comparison among pure STO, Al2O3-doped STO, and HfO2-doped STO MIM capacitors. Results revealed that STO MIM and HfO2-doped STO MIM capacitors both show higher capacitance densities, while the leakage current of the Al2O3-doped STO MIM is much lower than those of both the STO MIM and HfO2-doped STO MIM capacitors, which meets the strict requirement of the International Technology Roadmap for Semiconductors 2018. Therefore, the excellent result suggests that the Al2O3-doped STO film is a potential candidate material for dynamic random access memory and radio-frequency applications. (C) 2010 The Electrochemical Society. [DOI: 10.1149/1.3368671] All rights reserved.