Browsing by Author "Lee, Y. J."

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Advanced Metal-Gate/High-kappa CMOS with Small EOT and Better High Field Mobility
(2012)
Chin, Albert
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Chen, W. B.
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Chen, P. C.
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Wu, Y. H.
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Chi, C. C.
Continuously down-scaling the operation voltage, saving energy, and maintaining high performance are the major challenge for CMOS device. Small 0.95 similar to 1.4 nm equivalent-oxide thickness (EOT) and 1.4 similar to 2.5X better mobility than universal SiO2/Si data are achieved in metal-gate/high-kappa/Ge CMOS at 1 MV/cm effective field (E-eff). These excellent performances were achieved by using interface engineering and novel process, to overcome the poor high-kappa/Ge interface reaction, low source-drain dopant activation, and n(+)/p ohmic contact. The all-Ge CMOS with measured higher electron and hole mobility has irreplaceable merits of much simpler process, lower cost, and potentially higher yield than the InGaAs-nMOS/Ge-pMOS platform for IC manufacture.
Al(2)O(3)/Ga(2)O(3)(Gd(2)O(3)) passivation on In(0.20)Ga(0.80)As/GaAs-structural intactness with high-temperature annealing
(2010-04-07)
Lee, Y. J.
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Lee, C. H.
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Tung, L. T.
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Chiang, T. H.
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Lai, T. Y.
Molecular beam epitaxy grown Al(2)O(3)/Ga(2)O(3)(Gd(2)O(3))/In(0.20)Ga(0.80)As/GaAs has been rapidly thermal annealed to 850 degrees C in N(2). The hetero-structure remained intact, with the In(0.20)Ga(0.80)As/GaAs interface being free of misfit dislocation and In(0.20)Ga(0.80)As strained, as observed by high-resolution transmission electron microscopy and high-resolution x-ray diffraction using synchrotron radiation. Excellent capacitance-voltage characteristics as well as low electrical leakages were obtained. These structural and electrical results demonstrate that employing Ga(2)O(3)(Gd(2)O(3)) as a dielectric with an in situ Al(2)O(3) capping layer efficiently protects strained InGaAs layers from relaxing and volatilizing during rapid thermal annealing to 850 degrees C, important for fabricating inversion-channel InGaAs metal-oxide-semiconductor field-effect-transistors, a candidate for beyond the 16 nm node complementary MOS technology.
Al2O3/Ga2O3(Gd2O3) passivation on In0.20Ga0.80As/GaAs-structural intactness with high-temperature annealing
(2010-04-07)
Lee, Y. J.
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Lee, C. H.
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Tung, L. T.
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Chiang, T. H.
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Lai, T. Y.
Molecular beam epitaxy grown Al2O3/Ga2O3(Gd2O3)/In0.20Ga0.80As/GaAs has been rapidly thermal annealed to 850 degrees C in N-2. The hetero-structure remained intact, with the In0.20Ga0.80As/GaAs interface being free of misfit dislocation and In0.20Ga0.80As strained, as observed by high-resolution transmission electron microscopy and high-resolution x-ray diffraction using synchrotron radiation. Excellent capacitance-voltage characteristics as well as low electrical leakages were obtained. These structural and electrical results demonstrate that employing Ga2O3(Gd2O3) as a dielectric with an in situ Al2O3 capping layer efficiently protects strained InGaAs layers from relaxing and volatilizing during rapid thermal annealing to 850 degrees C, important for fabricating inversion-channel InGaAs metal-oxide-semiconductor field-effect-transistors, a candidate for beyond the 16 nm node complementary MOS technology.
Dichromatic InGaN-based white light emitting diodes by using laser lift-off and wafer-bonding schemes
(2007-04-16)
Lee, Y. J.
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Lin, P. C.
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Lu, T. C.
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Kuo, H. C.
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Wang, S. C.
An InGaN-based dual-wavelength blue/green (470 nm/550 nm) light emitting diode (LED) with three terminal operations has been designed and fabricated by using sapphire laser lift-off and wafer-bonding schemes. The device is equivalent to a parallel connection of blue and green LEDs; thus the effective electrical resistance of the device could be reduced. The luminous efficiency is 40 lm/W at 20 mA, accompanied by a broad electroluminescence emission with a combination of blue and green colors. This monolithically integrated dichromatic lighting structure has great potential in the application of the solid-state lighting. (c) 2007 American Institute of Physics.
Domain Matching Epitaxial Growth of High-Quality ZnO Film Using a Y(2)O(3) Buffer Layer on Si (111)
(2009-01-01)
Liu, W. -R.
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Li, Y. -H.
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Hsieh, W. F.
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Hsu, C. -H.
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Lee, W. C.
High-quality ZnO epitaxial films have been grown by pulsed-laser deposition on Si (111) substrates using a nanothick high-k oxide Y(2)O(3) buffer layer. Determined by X-ray diffraction and transmission electron microscopy, the epitaxial relationship between ZnO and Y(2)O(3) follows (0001)< 2 (1) over bar(1) over bar0 >(ZnO)parallel to(111)< 10 (1) over bar > Y(2)O(3). ZnO lattice aligns with the hexagonal O sublattice in Y(2)O(3) and the interfacial structure can be well described by domain matching epitaxy with 7 or 8 ZnO {11 (2) over bar0} planes matching 6 or 7 {4 (4) over bar0} planes Of Y(2)O(3) and lead to a significant reduction of residual strain. Superior optical properties were obtained even for ZnO films as thin as 0.21 mu m from photoluminescence results.
Domain Matching Epitaxial Growth of High-Quality ZnO Film Using a Y2O3 Buffer Layer on Si (111)
(2009-01-01)
Liu, W. -R.
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Li, Y. -H.
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Hsieh, W. F.
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Hsu, C. -H.
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Lee, W. C.
High-quality ZnO epitaxial films have been grown by pulsed-laser deposition on Si (111) substrates using a nanothick high-k oxide Y2O3 buffer layer. Determined by X-ray diffraction and transmission electron microscopy, the epitaxial relationship between ZnO and Y2O3 follows (0001)< 2 (1) over bar(1) over bar0 >(ZnO)parallel to(111)< 10 (1) over bar > Y2O3. ZnO lattice aligns with the hexagonal O sublattice in Y2O3 and the interfacial structure can be well described by domain matching epitaxy with 7 or 8 ZnO {11 (2) over bar0} planes matching 6 or 7 {4 (4) over bar0} planes Of Y2O3 and lead to a significant reduction of residual strain. Superior optical properties were obtained even for ZnO films as thin as 0.21 mu m from photoluminescence results.
Dynamic NBTI characteristics of PMOSFETs with PE-SiN capping
(2007-06-01)
Lu, C. Y.
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Lin, H. C.
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Lee, Y. J.
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電子工程學系及電子研究所
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Department of Electronics Engineering and Institute of Electronics
Negative-bias-temperature instability (NBTI) characteristics of strained p-channel metal-oxide-semiconductor field-effect transistors (PMOSFETs) under dynamic and AC stressing were investigated in this work. The compressive strain in the channel was deliberately induced by a plasma-enhanced chemical vapor deposition (PECVD) silicon nitride (SiN) capping layer in this study. It was found that the capping would degrade the NBTI characteristics, although the degradation is relieved when the stress frequency increases. The aggravated NBTI behaviors are ascribed to the higher amount of hydrogen incorporation during SiN deposition. (c) 2006 Published by Elsevier Ltd.
Fabrication and characterization of GaN-based LEDs grown on chemical wet-etched patterned sapphire substrates
(2006)
Lee, Y. J.
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Kuo, H. C.
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Lu, T. C.
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Su, B. J.
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Wang, S. C.
Characteristics of GaN-based light-emitting diodes (LEDs) grown on the chemical wet-etched patterned sapphire substrates (CWE-PSS) with different crystallography-etched facets were investigated. An improvement of 40% on the overall quantum efficiency was achieved by adopting this CWE-PSS scheme. A Monte Carlo ray-tracing method was employed to derive the optimized condition of sapphire etching time, and the calculated result demonstrated the same trend with real device measurement. Adopting the CWE-PSS in LEDs could not only improve the epitaxial quality but also increase the extraction quantum efficiency due to crystallography-etched facets efficiently scattering the guided light to enter the escape cone on the top of device surfaces. Finally, we observed better aging behaviors of CWE-PSS LEDs, which could be due to the reduction of threading dislocations of the epitaxial layers. (c) 2006 The Electrochemical Society.
Freestanding high quality GaN substrate by associated GaN nanorods self-separated hydride vapor-phase epitaxy
(2009-08-03)
Chao, C. L.
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Chiu, C. H.
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Lee, Y. J.
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Kuo, H. C.
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Liu, Po-Chun
This work proposes a method for fabricating 2 in. freestanding GaN substrates of high crystallographic quality and low residual strain. Arrays of GaN nanorods with sidewalls coated with silicon dioxide (SiO(2)) were randomly arranged on the sapphire substrate as a growth template for subsequent hydride vapor-phase epitaxy (HVPE). The passivation of the sidewalls coated with SiO(2) prevents the coalescence of GaN grains in spaces between the rods, causing them to grow preferentially on the top of individual rods. The proposed method significantly improves GaN crystal quality and results in self-separation from the underlying host sapphire substrate due to the relaxation of thermal strains in the HVPE cooling-down process.
Growth and structural characteristics of GaN/AlN/nanothick gamma-Al(2)O(3)/Si (111)
(2008-05-01)
Lee, W. C.
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Lee, Y. J.
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Tung, L. T.
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Wu, S. Y.
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Lee, C. H.
The authors report on the growth of GaN by nitrogen plasma-assisted molecular beam epitaxy (MBE) on a 2 in. Si (111) substrates with a nanothick (similar to 4.8 nm thick) gamma-Al(2)O(3) as a template/buffer. A thin layer of MBE-AlN similar to 40 nm thick was inserted prior to the growth of GaN. High-resolution transmission electron microscopy (HR-TEM) and high-resolution x-ray diffraction studies indicated that both of the nanothick gamma-Al(2)O(3) and AlN are a single crystal. Reflection high-energy electron diffraction, high-resolution x-ray scattering using synchrotron radiation, and cross-sectional HR-TEM measurements indicated an orientation relationship of GaN(0002)parallel to AlN(0002)parallel to gamma-Al(2)O(3)(111)parallel to Si(111) and GaN[10-10]parallel to AlN[10-10]parallel to gamma-Al(2)O(3)[2-1-1]parallel to Si[2-1-1]. A dislocation density of 5x(10(8)-10(9))/cm(2) in the GaN similar to 0.5 mu m thick was determined using cross-sectional TEM images under weak-beam dark-field conditions. (C) 2008 American Vacuum Society.
High Light-Extraction GaN-based Vertical LEDs With Double Diffuse Surfaces
(2007)
Lee, Y. J.
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Kuo, H. C.
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Lu, T. C.
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Wang, S. C.
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光電工程學系
High light-extraction (external quantum efficiency similar to 40%) 465-nm GaN-based vertical light-emitting diodes (LEDs) employing double diffuse surfaces were fabricated. The high scattering efficiency of double diffused surfaces could be responsible for the high light output power. (C)2006 Optical Society of America
High-quality nanothick single-crystal Y(2)O(3) films epitaxially grown on Si (111): Growth and structural characteristics
(2008-05-01)
Lee, Y. J.
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Lee, W. C.
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Nieh, C. W.
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Yang, Z. K.
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Kortan, A. R.
High-quality single-crystal nanothick Y(2)O(3) films have been grown epitaxially on Si (111) despite a lattice mismatch of 2.4%. The films were electron beam evaporated from pure compacted powder Y(2)O(3) target in ultrahigh vacuum. Y(2)O(3) 3 nm thick exhibited a bright, sharp, streaky reconstructed (4x4) reflection high energy electron diffraction pattern. Structural studies carried out by x-ray diffraction with synchrotron radiation and high-resolution transmission electron microscopy show that the films have the cubic bixbyite phase with a remarkably uniform thickness and high structural perfection. Two Y(2)O(3) domains of B-type Y(2)O(3) [2 (1) over bar(1) over bar]parallel to Si[11 (2) over bar] and A-type Y(2)O(3) [2 (1) over bar(1) over bar]parallel to Si[2 (1) over bar(1) over bar] coexist in the initial film growth with B type predominating over A type in thicker films as studied using x-ray diffraction. The narrow full width at half maximum of 0.014 degrees in the omega-rocking curve is the characteristic of excellent crystalline films. High-resolution transmission electron microscopy and fast Fourier transform analysis show atomically sharp interface and strain relaxation in thicker films. (C) 2008 American Vacuum Society.
InGaN/GaN nanostripe grown on pattern sapphire by metal organic chemical vapor deposition
(2007-01-01)
Ko, T. S.
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Wang, T. C.
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Gao, R. C.
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Lee, Y. J.
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Lu, T. C.
The authors have used metal organic chemical vapor deposition to grow InGaN/GaN multiple quantum well (MQW) nanostripes on trapezoidally patterned c-plane sapphire substrates. Transmission electron microscopy (TEM) images clearly revealed that the MQWs grew not only on the top faces of the trapezoids but also on both lateral side facets along the [0001] direction defined by the selected area electron diffraction pattern. Meanwhile, dislocations that stretched from the interfaces between the GaN and the substrates did not pass through the MQWs in the TEM observation. Microphotoluminescence measurements verified that the luminescence efficiency from a single nanostripe was enhanced by up to fivefold relative to those of regular thin film MQW structures. Observation of the cathodoluminescence identified the areas of light emission and confirmed that enhanced emission occurred from the nanostripes. (c) 2007 American Institute of Physics.
Investigation of Liquid Crystal Ripple Using Ericksen-Leslie Theory for Displays Subject to Tactile Force
(2013)
Lee, Y. J.
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Liu, T. S.
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Lin, Mao-Hsing
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Huang, Kun-Feng
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機械工程學系
Liquid crystal display panels subjected to tactile force will show ripple propagation on screens. Tactile forces change tilt angles of liquid crystal molecules and alter optical transmission so as to generate ripple on screens. Based on the Ericksen-Leslie theory, this study investigates ripple propagation by dealing with tilt angles of liquid crystal molecules. Tactile force effects are taken into account to derive the molecule equation of motion for liquid crystals. Analytical results show that viscosity, tactile force, the thickness of cell gap, and Leslie viscosity coefficient lead to tilt angle variation. Tilt angle variations of PAA liquid crystal molecules are sensitive to tactile force magnitudes, while those of 5CB and MBBA with larger viscosity are not. Analytical derivation is validated by numerical results.
Nano-roughening n-side surface of AlGaInP-based LEDs for increasing extraction efficiency
(2007-03-25)
Lee, Y. J.
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Lu, T. C.
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Kuo, H. C.
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Wang, S. C.
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Hsu, T. C.
A chemical wet etching technique is presented to form a nano-roughened surface with triangle-like morphology on n-side-up AlGaInP-based LEDs fabricated by adopting adhesive layer bonding scheme. A simple and commonly used H3PO4-based solution was applied for chemical wet etching. The morphology of nano-roughened surfaces is analyzed by the atomic force microscope (AFM) and significantly related to the enhancement factor of the LED output power. The output power shows 80% increase after optimizing the nano-roughened morphology of n-side surface, as compared to the ordinary flat surface LED. (c) 2006 Elsevier B.V. All rights reserved.
Structural Characteristics of Nanometer Thick Gd(2)O(3) Films Grown on GaN (0001)
(2010-12-01)
Chang, W. H.
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Chang, P.
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Lai, T. Y.
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Lee, Y. J.
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Kwo, J.
High-quality Gd(2)O(3) epi-films 5-20 nm thick have been grown on GaN (0001) using molecular beam epitaxy A detailed structural investigation was carried out by in situ reflection high energy electron diffraction cross sectional transmission electron microscopy, and X-ray scattering using a synchrotron radiation source The films consist of the high temperature monoclinic (m) phase with six rotational domains which can be easily mistaken for being the hexagonal phase All the domains follow the m-Gd(2)O(3) ((2) over bar 01)< 020 > parallel to GaN (0001) < 11<(2)over bar>0 > orientational relationship
Structural Characteristics of Nanometer Thick Gd2O3 Films Grown on GaN (0001)
(2010-12-01)
Chang, W. H.
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Chang, P.
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Lai, T. Y.
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Lee, Y. J.
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Kwo, J.
High-quality Gd2O3 epi-films 5-20 nm thick have been grown on GaN (0001) using molecular beam epitaxy A detailed structural investigation was carried out by in situ reflection high energy electron diffraction cross sectional transmission electron microscopy, and X-ray scattering using a synchrotron radiation source The films consist of the high temperature monoclinic (m) phase with six rotational domains which can be easily mistaken for being the hexagonal phase All the domains follow the m-Gd2O3 ((2) over bar 01)< 020 > parallel to GaN (0001) < 11<(2)over bar>0 > orientational relationship
Structure of HfO2 films epitaxially grown on GaAs(001)
(2006-09-18)
Hsu, C. -H.
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Chang, P.
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Lee, W. C.
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Yang, Z. K.
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Lee, Y. J.
High-quality HfO2 films of technologically important thickness ranging from 1.8 to 17 nm have been grown epitaxially on GaAs (001) by molecular beam epitaxy. Thorough structural and morphological investigations were carried out by x-ray scattering and high-resolution transmission electron microscopy. The films exhibit an atomically sharp interface with the substrate and are of a monoclinic phase with predominant (001)-plane epitaxy between the HfO2 films and GaAs, in spite of a large lattice mismatch of > 8.5%.
Study of LC Ripple Caused by Tactile Force Acting on Display
(2012-01-01)
Lee, Y. J.
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Liu, T. S.
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Lin, Mao-Hsing
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Huang, Kun-Feng
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機械工程學系
Liquid crystal display (LCD) panels subjected to tactile force will show ripple propagation on screens. The Ericksen-Leslie theory is used to investigate ripple propagation that results from liquid crystal molecule tilt. Tactile-force effects are taken into account to derive the molecule equation of motion for liquid crystals.
The Growth of an Epitaxial ZnO Film on Si(111) with a Gd(2)O(3)(Ga(2)O(3)) Buffer Layer
(2011-07-01)
Lin, B. H.
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Liu, W. R.
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Yang, S.
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Kuo, C. C.
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Hsu, C. -H.
High-quality (0001)-oriented ZnO epitaxial films have been grown by pulsed laser deposition on Si(111) buffered with a nanometer-thick Gd(2)O(3)(Ga(2)O(3)), GGO, layer. The structural characteristics of the ZnO epi-layers were studied by X-ray diffraction and transmission electron microscopy (TEM). The in-plane epitaxial relationship between the wurtzite ZnO, cubic GGO, and cubic Si follows {10 (1) over bar0}(ZNO)parallel to{4 (22) over bar}(Gd2O3)parallel to{(4) over bar 22}(Si) and the ZnO/GGO interface can be described by the domain matching epitaxy. TEM contrast analysis reveals that the major defect structures in the ZnO films are edge-type threading dislocations and intrinsic basal plane stacking faults. All the ZnO epi-films studied are under a tensile biaxial strain, but no cracks were found. Temperature-dependent photoluminescence results show the excellent optical properties of the obtained ZnO layers, and the origins of the spectral features are discussed.