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PCSEL Performance of Type-I InGaAsSb Double-QWs Laser Structure Prepared by MBE
(2019-01-02)
Cheng, Hui-Wen
;
Lin, Shen-Chieh
;
Li, Zong-Lin
;
Sun, Kien-Wen
;
Lee, Chien-Ping
This paper discusses the issue of controlling the epitaxial growth of mixed group V alloys to form a type-I InGaAsSb/AlGaAsSb double quantum wells (QWs) structure. We also discuss the run-to-run reproducibility of lattice-matched AlGaAsSb alloys and strained In0.35Ga0.65As0.095Sb0.905 in terms of growth parameters (V/III ratio, Sb-2/As-2 ratio). Molecular beam epitaxy (MBE) was used to grow two type-I InGaAsSb double-QWs laser structures differing only in the composition of the bottom cladding layer: Al0.85Ga0.15As0.072Sb0.928 (sample A) and Al0.5Ga0.5As0.043Sb0.957 (sample B). Both samples were respectively used in the fabrication of photonic crystal surface-emitting lasers (PCSELs). Sample A presented surface lasing action from circular as well as triangular photonic crystals. Sample B did not present surface lasing due to the deterioration of the active region during the growth of the upper cladding. Our findings underline the importance of temperature in the epitaxial formation of AlxGa1-xAsySb1-y in terms of lasing performance.
Statistical Simulation of Static Noise Margin Variability in Static Random Access Memory
(2010-11-01)
Li, Yiming
;
Cheng, Hui-Wen
;
Han, Ming-Hung
;
傳播研究所
;
電機工程學系
In this paper, we examine the impact of random-dopant-fluctuation (RDF), process-variation-effect (PVE), and workfunction-fluctuation (WKF), on 16-nm-gate metal-oxide-semiconductor field-effect-transistor (MOSFET) static random access memory (SRAM) cells. For planar MOSFETs with a threshold voltage (V(th)) of 140mV, the nominal static noise margin (SNM) of six-transistor (6T)-SRAM with unitary cell ratio (CR) is only 20mV; and the normalized SNM fluctuations (SNM) induced by RDF, PVE, and WKF are 80%, 31%, and 48%, respectively, which may damage SRAM's operation. Two improvement approaches are further implemented; first, eight-transistor (8T)-SRAM and 6T-SRAM with increased CR are examined. Compared with the conventional 6T-SRAM, under the same Vth, the SNM of 8T-SRAM is enlarged to 233 mV and the corresponding RDF, PVE, and WKF-induced SNM are reduced to 9.5%, 6.4%, and 7%, respectively, at a cost of 30% extra chip area. Without increasing chip area, device with raised Vth, doping profile engineering and using silicon-on-insulator fin-type field-effect transistors (SOI FinFETs) are further advanced. The 6T SOI FinFETs SRAM exhibits the smallest sigma SNM, with merely 5.3%, 1.2%, and 2.3%, resulting from RDF, PVE, and WKF, respectively, where the value of SNM is equal to 125 mV.
Field emission property of carbon nanotube field emitters in triode structure fabricated with anodic aluminum oxide templates
(2008-04-01)
Li, Yiming
;
Cheng, Hui-Wen
;
Lin, Chen-Chun
;
Pan, Fu-Ming
;
材料科學與工程學系
In this work, we study the field emission (FE) properties of carbon nanotubes (CNTs) field emitters in the triode structure fabricated with anodic aluminum oxide (AAO) template. To obtain the self-consistent solution, a set of Maxwell's equations coupling with Lorentz equation are solved simultaneously using finite difference time domain (FDTD) particle-in-cell (PIC) method. The FE current is then computed with the Fowler-Nordheim equation. To validate our simulation model, we firstly calibrate the collected electron current density between the measurement data of fabricated AAO-CNTs and simulation result. We find that the high density of CNTs will result in large screening effect among adjacent emitters and reduce the strength of electric field. Consequently, it significantly affects the collected emission current density. Our prediction shows that more than three-order magnitude difference on the collected emission current density could be observed when the spacing between CNTs is decreased from 0.7 to 0.233 mu m for the explored structure with the diameter of 7 mu m. Effects of random heights and thickness of oxide on the FE property of structure are also discussed.
Interface traps and random dopants induced characteristic fluctuations in emerging MOSFETs
(2011-07-01)
Li, Yiming
;
Cheng, Hui-Wen
;
Chiu, Yung-Yueh
;
傳播研究所
;
電機工程學系
In this work, we study the effect of interface traps (ITs) and random dopants (RDs) on characteristics of 16-nm MOSFETs. Totally random generated devices with 2D ITs between the interface of silicon and HfO(2) film as well as 3D RDs inside the silicon channel are simulated. Fluctuations of threshold voltage and on/ off state current for devices with different EOT of insulator film are analyzed and discussed. The results of this study indicate ITs and RDs statistically correlate to each other and RDs govern device variability, compared with the influence of ITs. Notably, the position of ITs and RDs induces rather different fluctuation in spite of the same number of ITs and RDs are investigated. (C) 2011 Elsevier B.V. All rights reserved.
Nanosized metal grains induced electrical characteristic fluctuation in 16-nm-gate high-kappa/metal gate bulk FinFET devices
(2011-07-01)
Li, Yiming
;
Cheng, Hui-Wen
;
Yiu, Chun-Yen
;
Su, Hsin-Wen
;
傳播研究所
In this work, the work function fluctuation (WKF) induced variability in 16-nm-gate bulk N-FinFET is for the first time explored by an experimentally calibrated 3D device simulation. Random nanosized grains of TiN gate are statistically positioned in the gate region to examine the associated carriers' transport, concurrently capturing "grain number variation" and "grain position fluctuation." The newly developed localized WKF simulation method enables us to estimate the threshold voltage fluctuation of devices with respect to the aspect ratio (AR = fin height/fin width) which accounts for the random grain's size, number and position effects simultaneously. (C) 2011 Elsevier B.V. All rights reserved.
Numerical simulation of field emission efficiency of anodic aluminum oxide carbon nanotube field emitter in the triode structure
(2008-07-01)
Li, Yiming
;
Cheng, Hui-Wen
;
電信工程研究所
;
Institute of Communications Engineering
In this work, we study the field emission (FE) properties of carbon nanotubes (CNTs) field emitter in the triode structure fabricated with anodic aluminum oxide (AAO) template. To obtain the self-consistent solution, a set of two-dimensional Maxwell's equations coupling with Lorentz equation are solved with a finite difference time domain (FDTD) particle-in-cell (PIC) method. The FE current is then computed with the Fowler-Nordheim equation. Calculated result of the collected current density shows good agreement with the measured data for the fabricated sample. Effect of the height and number of CNTs on the collected electron current density is thus investigated. We find that the explored structure with few number of CNTs exhibit high current density due to insignificant screening effect. The current density is low and approaches to stable current level when the number of CNTs increases. The simulation further predicts that the structure with the height of CNTs = 0.42 mu m has a maximum current density. The FE efficiency (i.e., the collected electron current density/the emission current density) versus the number of CNTs is estimated. The explored AAO-CNTs triode structure maintains high FE efficiency (similar to 95%) with a nonzero gate voltage. (C) 2008 Elsevier B.V. All rights reserved.
Discrete-Dopant-Fluctuated Transient Behavior and Variability Suppression in 16-nm-Gate Complementary Metal-Oxide-Semiconductor Field-Effect Transistors
(2009-04-01)
Li, Yiming
;
Hwang, Chih-Hong
;
Cheng, Hui-Wen
;
電信工程研究所
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Institute of Communications Engineering
Variability in the characteristics of nanoscale complementary metal-oxide-semiconductor (CMOS) field-effect transistors is a major challenge to scaling and integration. However, little attention has been focused on the existence of transient behavior fluctuations of devices owing to random dopant placement. In this study, we explore the discrete-dopant-induced transient behavior fluctuations of 16-nm-gate CMOS circuits through a three-dimensional large-scale statistically sound "atomistic" device-circuit-coupled simulation approach, concurrently capturing "dopant concentration variation" and "dopant position fluctuation". For a 16-nm-gate CMOS inverter, a 3.5% variation of the rise time, a 2.4% variation of the fall time, an 18.3% variation of the high-to-low delay time, and a 13.2% variation of the low-to-high delay time are estimated and discussed. Fluctuation suppression techniques proposed from the device and the circuit viewpoints are implemented to examine the associated intrinsic fluctuations. (C) 2009 The Japan Society of Applied Physics
Quantum hydrodynamic simulation of discrete-dopant fluctuated physical quantities in nanoscale FinFET
(2011-01-01)
Li, Yiming
;
Cheng, Hui-Wen
;
Han, Ming-Hung
;
傳播研究所
;
電機工程學系
Impact of the discrete dopants on device performance is crucial in determining the behavior of nanoscale semiconductor devices Atomistic quantum mechanical device simulation for studying the effect of discrete dopants on device s physical quantities is urgent This work explores the physics of discrete-dopant-induced characteristic fluctuations in 16-nm fin-typed field effect transistor (FinFET) devices Discrete dopants are statistically positioned in the three-dimensional channel region to examine associated carrier's characteristic concurrently capturing "dopant concentration variation" and "dopant position fluctuation" An experimentally validated quantum hydrodynamic device simulation was conducted to investigate the potential profile and threshold voltage fluctuations of the 16-nm FinFET Results of this study provide further insight into the problem of fluctuation and the mechanism of immunity against fluctuation in 16-nm devices (C) 2010 Elsevier BV All rights reserved
Investigation of Raman enhancement in hydrothermally roughened SERS-active substrates
(2011-01-01)
Cheng, Hui-Wen
;
Li, Yiming
;
Yang, Jung-Yen
;
電機工程學系
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Department of Electrical and Computer Engineering
In this work we study surface enhanced Raman spectroscopy (SERS) active substrates for the detection of Rhodamine 6G To examine the electromagnetic enhancement we apply the finite-difference time-domain (FDTD) algorithm to analyze the structures by solving a set of coupled Maxwell's equations (Ampere s Law and Faraday s Law) in differential form The field enhancements are thus investigated in the visible regime with the wavelength of 633 nm In our experimental measurement the surface enhanced Raman scattering signals from the surface of substrates with 12-hour treatment and without treatment are performed and compared Through the three-dimensional (3D) FDTD calculation we find that the hydrothermally 12-hour treated samples possess significantly vertical variations of surface and thus have relatively larger field enhancement than those without treated Consequently it implies a strong positive effect on the surface enhancement which is consistent with the measured intensity (C) 2010 Elsevier B V All rights reserved
Design of Miniaturized Antenna and Power Harvester Circuit on the Enucleated Porcine Eyes
(2014-01-01)
Cheng, Hui-Wen
;
Yu, Tsung-Chi
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Huang, Hong-Yi
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Ting, Ssu-Han
;
Huang, Tzuen-Hsi
This letter describes a prototype of a miniaturized rectifying antenna (rectenna) design for the wireless powering of an ocular device. In contrast to the conventional on-lens loop antenna, this letter presents a loop antenna with stepped structures for optimal impedance to the rectifier. The return loss of the antenna less than -15 dB at 3 GHz is accomplished in a contact lens with a diameter ranging from 10 to 15 mm. Additionally, the radio frequency (RF) rectifier and voltage-boosting network (VBN) are optimized to enhance the power conversion efficiency (PCE) by using the voltage boosting technique. Experimental results indicate that the optimal rectifier, which is fabricated with the TSMC 0.18-mu m process, produces a dc output voltage of 2.94 V and a conversion efficiency of 31% across a resistive 3.5 k Omega load with an input power of +9 dBm. Moreover, the rectenna under the experiment with an enucleated porcine eye can be powered wirelessly with a transmitting device at a distance of 4 cm. The output power is 2.01 mW with a transmitting power of +32 dBm for the wireless ocular physiological monitoring (WOPM) system. Importantly, this letter demonstrates the feasibility of an optimal miniaturized on-lens rectenna design, capable of overcoming the RF power attenuation on the ocular tissue to increase the delivering distance and reduce the transmitting power.

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