Jane P. Chang

University of California, Los Angeles, Los Angeles, California, United States

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Publications (88)160.14 Total impact

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    ABSTRACT: Lithium (Li)-ion batteries have drawn much attention for their outstanding performance in portable electronic applications. These batteries have the potentials to function as miniaturized power source for microelectromechanical (MEMS) devices through the fabrication of 3-dimensional configurations. To fabricate a fully functional 3D Li-ion microbattery, however, an ultra-thin and highly conformal electrolyte layer is required to coat the 3D electrodes. The solid oxide Li-ion conductor, lithium aluminosilicate (LixAlySizO, LASO), synthesized by atomic layer deposition (ALD) is a promising electrolyte material for 3D battery applications owing its adequate ionic conductivity as well as improved electrode stability. The self-limiting characteristic of ALD allows for precise control of thickness and composition of complex oxides and results in a highly conformal and pinhole-free coating even on highly complex structures such as high aspect ratio 3D electrodes. The metal precursors, lithium t-butoxide (LTB), trimethylaluminum (TMA), tris(tert-butoxy)silanol (TTBS), and tetraethylorthosilicate (TEOS) were used to form LixAlySizO via ALD. In-situ FTIR was implemented to study the incubation time and growth mechanisms of each constituent oxide on the other to improve the controllability of deposited films. In-situ FTIR studies revealed that the growth mechanism of silicon oxide is strongly affected by the underlying oxide layer, exhibiting different surface reaction mechanisms during the incubation stage. Li-ion conductivities and the activation energy of as-deposited LASO/LAO/LSO films with respect to lithium contents and the film thickness were studied. The LASO ALD coating on 3D carbon array posts were confirmed to be conformal and uniform using transmission electron microscopy (TEM) imaging. A Li-ion half-cell consisting of LASO coated on 3D carbon array electrode has shown promising improvement in efficiency when compared to bare electrode. Lithiation cycling tests of thin LASO/LAO/LSO films were found to be functions of both composition and thickness. The reversibility and kinetics of insertion as well as the effect on the cycling stability from the direct deposition of LASO/LAO/LSO on potential anode materials, SiNWs were also investigated using in-situTEM observations during lithiation.
    14 AIChE Annual Meeting; 11/2014
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    ABSTRACT: Thin films of a solid electrolyte, lithium aluminosilicate, were synthesized by atomic layer deposition (ALD) for potential applications in 3D Li-ion microbatteries. The films were deposited at 290 °C via alternating the ALD growth of the constituents, LiOH, Al2O3 and SiO2. Manipulation of the cation composition and thickness was achieved through well-controlled surface reactions during each precursor pulse cycle. Various compositions were obtained by changing the number of pulse cycles for each precursor, which enabled lithium aluminate (LixAlyO), lithium aluminosilicate (LixAlySizO) and stoichiometric LiAlSiO4 materials to be prepared. The as-deposited ALD films were amorphous and formed conformal coatings over Si nanowires. Films as thin as 6 nm were found to be free of pinholes. Complex impedance measurements confirmed that the films were ionic conductors with the room temperature conductivity in the range of 10−7 to 10−9 S cm−1 and an activation energy between 0.46 and 0.84 eV, depending upon the film composition.
    J. Mater. Chem. A. 06/2014; 2(25).
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    ABSTRACT: The effect of oxygen addition to chlorine plasma during shallow trench isolation etching is quantified in this work. Specifically, the electron density and the electron temperature in an electron cyclotron resonance reactor were characterized by a Langmuir probe and were found to remain relatively constant upon O2 addition. The silicon etching rates were found to increase with the square root of the ion energy, suggesting the etching reaction is limited by the momentum transfer from ions to the surface. A relatively small amount of oxygen addition (<10%) to the chlorine plasma simultaneously changes the reactor wall conditions and surface kinetics, since oxygen becomes actively involved in the surface reactions. The change in the chamber wall conditions and surface kinetics leads to the change in both the amount of etch products and the etched feature profile. The incorporation of oxygen on the surface results in a significant change of the etched surface morphology and its composition. This work suggests a small amount of O2 addition to Cl2 plasmas in shallow trench isolation etching changes the etching behavior primarily through modifying the kinetics on etched surfaces. A multiscale etch model consisting of translating mixed layer and Monte Carlo modules for bulk and feature scale etching, respectively, was successfully applied to this case, demonstrating good agreement with the experimental results.
    Journal of vacuum science & technology. B, Microelectronics and nanometer structures: processing, measurement, and phenomena: an official journal of the American Vacuum Society 01/2013; 31(4):042201-042201-12. · 1.36 Impact Factor
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    ABSTRACT: The incubation time during atomic layer deposition (ALD) of lead oxide, zirconium oxide, and titanium oxide on each other was quantified in order to precisely control the composition of lead zirconate titanate (PZT). The desired stoichiometry of Pb:Zr:Ti=2:1:1, which yields the desired ferroelectricity, was found to depend strongly on the ALD sequence, the substrate of choice, as well as the postdeposition annealing temperature. With the desired stoichiometry, the ferroelectric and piezoelectric properties of the PZT films were validated by polarization–voltage hysteresis loop and piezoresponse force microscopy, respectively, demonstrating that ALD method is a viable technique for ultra thin ferroelectric films for device applications.
    Journal of Vacuum Science & Technology B Microelectronics and Nanometer Structures 01/2013; 31(1):2207-. · 1.36 Impact Factor
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    ABSTRACT: Lithium (Li)-ion batteries have drawn much attention for their outstanding performance in portable electronics applications with the potentials to function as a power source for further minizaturized devices, including micro-systems through the utilization of 3-dimensional electrodes based on high aspect ratio pillars. To realize this potential, an ultra-thin and highly conformal electrolyte layer is needed to coat the 3D electrode array. The ionic conductor lithium aluminosilicate (LiAlSiO4) synthesized by atomic layer deposition (ALD) is a promising electrolyte material for 3D battery applications not only due to its high ionic conductivity along its c-axis resulting from channels formed by the alternating tetrahedra of aluminum-oxygen (Al-O) and silicon-oxygen (Si-O), but also expected to provide similar improved cell cyclability, as reported in the preliminary studies of ultra-thin metal-oxide ALD coatings on electrodes. The self-limiting characteristic of ALD allows for precise control of thickness and composition of complex oxides and results in a highly conformal and pinhole-free coating suitable in 3D micro-battery applications or electrolyte surface coatings. The metal precursors used in this work are tetraethyl orthosilicate (TEOS), trimethylaluminum (TMA) and lithium t-butoxide (LTB). These precursors, along with water vapor as the oxidant, were used to deposit SiO2, Al2O3 and Li2O, with the deposition rates in the range of 0.8~2Å/cycle, respectively. The deposition rate of stoichiometric LiAlSiO4 was ~20Å/cycle at a temperature of 290°C. The concentration of each metal element in LixAlySizO (LASO) thin films was found to correlate closely to ALD cycles and the associated incubation times. The crystallinity of the films after post-deposition rapid thermal annealing (RTA) was a function of cation atomic percentage. Li-ionic conductivities and the activation energy of as-deposited LASO films with respect to lithium contents as well as their relation to the film thickness were studied. The LASO ALD coating on 3D features, such as NWs and nanopaticles (NPs), were confirmed to be conformal and uniform by transmission electron microscopy (TEM) imaging. The cell performance as well as cyclability enhancement from LixAlySizO was investigated for a silicon-nanowire 3D microbattery, where SiNW was used as an anode, to explore the potentials of a solid-state SiNW battery with a solid-oxide electrolyte.
    12 AIChE Annual Meeting; 10/2012
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    ABSTRACT: Rare-earth (RE = Eu, Dy, Tb, and Ce) ion doped core and core–shell LaPO4 phosphors were synthesized to elucidate the effect of spatial distribution of dopants on the emission spectra. The core–shell architecture was designed as a single particle that can be excited by a single wavelength and yield a balanced white light appearance with long emission lifetimes. Specifically, a multishell architecture was employed to separate the Eu3+ and Tb3+ within the phosphor to circumvent the energy transfer between them, passivate the surface quenching sites, and control Ce3+ doping to sensitize other RE ions. To assess the effectiveness of these core–shell phosphors, the International Commission on Illumination (CIE) coordinates and luminescence lifetimes are quantified as the figures of merit. The Eu3+:LaPO4|Ce3+,Dy3+:LaPO4|Tb3+:LaPO4 layering resulted in CIE coordinates of (0.34, 0.35) using 365 nm excitation, nearly at center of the white light regime at (0.35, 0.35). Finally, the emission lifetimes were measured to be 0.85, 4.34, and 3.26 ms and resulted in a total increase of 31, 36, and 16% over the RE3+:LaPO4 reference phosphors, where RE = Dy, Tb, and Eu, respectively. The synthesized phosphor material has high-quality white light with improved emission lifetimes, suitable for application in white light LED devices.
    The Journal of Physical Chemistry C. 06/2012; 116(23):12854–12860.
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    ABSTRACT: Rare-earth (RE) (Er3+ and Yb3+, Er3+)-doped yttrium oxide (Y2O3) core–shell particles were synthesized in this work using a two-step process where the cores were formed by molten salt synthesis while the shell was deposited by a sol–gel process. The cores were 100–150 nm, and a shell layer, up to 12 nm thick, was controllable based on the mass ratio between the RECl3 salts and the Er3+:Y2O3 (1 mol %) particles. A passive Y2O3 shell layer, at an optimal thickness around 8 nm, passivated the surface quenching sites and resulted in a 53% increase in photoluminescence lifetimes and visible separation in Stark splitting. Optically active shell layers, such as Yb2O3 and Yb3+:Y2O3, not only passivated the quenching sites but also facilitated energy transfer between the spatially controlled RE ions. Furthermore, the effect of surface passivation on the upconversion luminescence was determined through the purposed dynamic processes to corroborate the effect of the hydroxyl groups on energy dissipation. The addition of a passive shell layer or a sensitizer reduced the upconversion to a two-photon process due to a decreased branching ratio at the 4I11/2 energy level. Yb2O3 is deemed the most effective shell material due to the largest increase photoluminescence intensity at 1535 nm as a function of the pump power and the lifetime of the 4S3/2 radiative transition, important in upconversion luminescence. The increased lifetime and low pump power achieved with Er3+:Y2O3|Yb2O3 core–shell phosphors hold promise in lighting devices for improved overall device efficiency.
    The Journal of Physical Chemistry C. 04/2012; 116(18):10333–10340.
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    ABSTRACT: To predict and optimize luminescence efficiency of rare-earth ion doped (RE) nanophosphors, a relationship between the RE-concentration and the luminescent parameters is often obtained by Judd-Ofelt analysis, where the quality factor (χ = Ω4/Ω6) depends on the Er interactions with other RE elements in the second nearest neighboring shell. In this work, a detailed analysis of the local bonding environment by extended x-ray absorption fine structure (EXAFS) analyses is shown as effective as the Judd-Ofelt analysis to quantify the Er↔RE interaction in the second nearest neighboring shell (ρN = IREr↔RE2/IREr↔RE1). As the physical basis of ρN is consistent to that of χ, the EXAFS analysis becomes a viable alternative to replace Judd-Ofelt analysis to predict the optimum dopant concentration. This approach was corroborated based on analysis of Er3+:Y2O3 and core-shell Er3+:Y2O3|Y2O3 (5 nm shell) nanoparticles (NPs), with Er3+ concentrations up to 20 mol %. The ρN ratio from EXAFS analysis was shown to strongly correlate to the lifetimes extracted from the Judd-Ofelt analysis, both predicting the optimal dopant concentrations to be at 5 mol % and 2 mol % for the Er3+:Y2O3 and core-shell NPs, respectively. This confirms that EXAFS analysis can be used as a more time efficient method to achieve the same outcome typically obtained by Judd-Ofelt analysis, enabling the optimization of the luminescent lifetimes of RE doped nano-phosphors.
    Journal of Applied Physics 04/2012; 111(8). · 2.21 Impact Factor
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    ABSTRACT: Di-block copolymer synthesized Co/Al2O3 core-shell nanocrystal (NC) capacitors were fabricated in order to study the temperature-dependent electron transport. The capacitance-voltage memory window is shown to increase proportionally with the substrate temperature, saturating at 3.5 V, at 175 °C. At elevated operating temperatures, the tunneling of electrons increases, resulting in large flatband voltage shift. Furthermore, the electron leakage of the NCs at high temperature is faster than the leakage at room temperature due to thermally assisted tunneling. The activation energy is determined by exponentially fitting the thermally dependent retention performance, which was then used to model the occupied energy levels and further elucidate the electron transport within the NC memory.
    Journal of Applied Physics 03/2012; 111(6). · 2.21 Impact Factor
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    ABSTRACT: Tin (Sn) crystal growth on Sn-based anodes in lithium ion batteries is hazardous for reasons such as possible short-circuit failure by Sn whiskers and Sn-catalyzed electrolyte decomposition, but the growth mechanism of Sn crystals during battery cycling is not clear. Here we report different growth mechanisms of Sn crystal during the lithiation and delithiation processes of SnO(2) nanowires revealed by in situ transmission electron microscopy (TEM). Large spherical Sn nanoparticles with sizes of 20-200nm grew instantaneously upon lithiation of a single-crystalline SnO(2) nanowire at large current density (j>20A/cm(2)), which suppressed formation of the Li(x)Sn alloy but promoted agglomeration of Sn atoms. Control experiments of Joule-heating (j≈2400A/cm(2)) the pristine SnO(2) nanowires resulted in melting of the SnO(2) nanowires but not Sn particle growth, indicating that the abnormal Sn particle growth was induced by both chemical reduction (i.e., breaking the SnO(2) lattice to produce Sn atoms) and agglomeration of the Sn atoms assisted by Joule heating. Intriguingly, Sn crystals grew out of the nanowire surface via a different "squeeze-out" mechanism during delithiation of the lithiated SnO(2) nanowires coated with an ultra-thin solid electrolyte LiAlSiO(x) layer. It is attributed to the negative stress gradient generated by the fast Li extraction in the surface region through the Li(+)-conducting LiAlSiO(x) layer. Our previous studies showed that Sn precipitation does not occur in the carbon-coated SnO(2) nanowires, highlighting the effect of nanoengineering on tailoring the electrochemical reaction kinetics to suppress the hazardous Sn whiskers or nanoparticles formation in a lithium ion battery.
    Micron 02/2012; 43(11):1127-33. · 1.88 Impact Factor
  • Nathan Marchack, Jane P Chang
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    ABSTRACT: The invention of the transistor followed by more than 60 years of aggressive device scaling and process integration has enabled the global information web and subsequently transformed how people communicate and interact. The principles and practices built upon chemical processing of materials on silicon have been widely adapted and applied to other equally important areas, such as microfluidic systems for chemical and biological analysis and microscale energy storage solutions. The challenge of continuing these technological advances hinges on further improving the performance of individual devices and their interconnectivity while making the manufacturing processes economical, which is dictated by the materials' innate functionality and how they are chemically processed. In this review, we highlight challenges in scaling up the silicon wafers and scaling down the individual devices as well as focus on needs and challenges in the synthesis and integration of multifunctional materials.
    Annual Review of Chemical and Biomolecular Engineering 01/2012; 3:235-62. · 7.51 Impact Factor
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    ABSTRACT: The development of rare-earth (RE) doped phosphors allows for the conversion of photons to energies that are more usable for the desired application. Additionally, these RE phosphors have long lifetimes, on the order of ms, which offer potential in many energy conversion and energy transfer devices. Currently, RE phosphors are used in fiber optics amplifiers, modulated hybrid laser, optical interconnects and switches, optical displays, broad absorption solar cells and various other lighting applications. Energy transfer mechanisms of the excited RE states, such as defect quenching and sensitizer/emitter interactions, must be understood in order to achieve high efficiency energy conversion and propagation for future applications. In order to synthesize high efficiency phosphors, trivalent RE ions are being doped into a core-shell metal oxide host lattice. The role of the core-shell structure reduces the effect of the surface quenching sites by increasing the distance between active ions and the surface hydroxyl groups. Secondly, the luminescent fingerprint can be further controlled with proper doping of the shell structure by either increasing the absorption spectrum or adding additional emission peaks. Primarily, this work focuses on the emission of visible photons through upconversion in Y2O3:Er3+, Yb3+ nanophosphors, making them ideal components in broad absorption solar cells. By spatially controlling the position and concentration of the RE ions within the nanostructure, increased luminescence is observed due to energy transfer between the dopant ions within a critical interatomic distance. Passitvation of surface sites with increasing shell thickness was shown to increase luminescent lifetimes up to 53%, with a critical shell thickness of 8 nm, while lowering the theoretical lifetimes extracted from Judd-Ofelt parameters. The effect of the spatially controlled Yb ions was probed through the extraction of the upconversion photon requirement, showing a statistical decrease in photons from 2.16 to 1.43, or ~30 %. Finally, the effective energy transfer distance and energy transfer coefficients were studied by selectively exciting the Yb 4F5/2-4F7/2 transition with a 904 nm laser diode while probing the Er3+ emission at 1540 nm as a Y2O3 spacer layer is added to the system. Measured results show the occurrence of energy transfer between the ions with a ~3 nm spacer layer, confirming the prediction of the Föester-Dexter theory. Additionally, these results are applied to a RE doped LaPO4 system, producing white light from a single, high efficiency core-shell phosphor.
    2011 AIChE Annual Meeting; 10/2011
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    ABSTRACT: Atomic layer deposited (ALD) Pb(Zr,Ti)Ox (PZT) ultra-thin films were synthesized on an ALD Al2O3 insulation layer on 4H-SiC substrate for metal-ferroelectric-insulator-semiconductor (MFIS) device applications. The as-deposited PZT was amorphous but crystallized into a perovskite polycrystalline structure with a preferred [002] orientation upon rapid thermal annealing (RTA) at 950 °C. The capacitance-voltage and current-voltage characteristics of the MFIS devices indicate carrier injection to the film induced by polarization and Fowler-Nordheim (FN) tunneling when electric field was high. The polarization-voltage measurements exhibited reasonable remanent and saturation polarization and a coercive electrical field comparable to that reported for bulk PZT. The piezoresponse force microscope measurements confirmed the polarization, coercive, and retention properties of ultra-thin ALD PZT films.
    Journal of Applied Physics 06/2011; 109(12):124109-124109-4. · 2.21 Impact Factor
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    ABSTRACT: An ordered Co/Al2O3 core-shell nanocrystal (NC) nonvolatile memory device was fabricated. Self-assembled diblock copolymer process aligned the NCs with uniform size. Co/Al2O3 core-shell NCs were formed using atomic layer deposition of Al2O3 before and after the ordered Co NC formation. Compared to Co NC memory, Co/Al2O3 core-shell NC memory shows improved retention performance without sacrificing writing and erasing speeds.
    Applied Physics Letters 05/2011; 98(19):192107-192107-3. · 3.52 Impact Factor
  • Nathan Marchack, Jane P Chang
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    ABSTRACT: Plasmas have been widely utilized to pattern various materials, from metals to semiconductors and oxides to polymers, for a vast array of applications. The interplay between physical, chemical and material properties that comprises the backbone of plasma etching is discussed in this perspective paper, with a focus on the needed tools and approaches to address the challenges facing plasma etching and to realize the desired pattern transfer fidelity at the nanoscale.
    Journal of Physics D Applied Physics 04/2011; 44(17):174011. · 2.53 Impact Factor
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    ABSTRACT: As the downscaling of integrated circuit devices continues, the effect of variations in feature profile evolution from processing techniques such as plasma etching becomes greatly magnified. In order to accurately simulate such processes, modeling across a variety of length and time scales is required, from the bulk discharge in the reactor to the material surface layers. The complexity of this task is compounded by the fact that etching and deposition reactions often take place concurrently, which must be taken into account even if the net effect of the process is known. We adapt a previously developed phenomenological model1 for use in conjunction with reactor scale and Monte Carlo based simulation tools, with the ultimate goal of predicting feature profile evolution. Experimental measurements or reactor-scale simulations are used to obtain species fluxes,2 and agreement with reported results in literature are examined. The aforementioned surface site-based phenomenological model has demonstrated predictive capabilities for both etching and deposition processes, but can not be readily integrated with the cell based Monte Carlo method. Therefore, a translated mixed layer kinetics (TML) model3 is utilized to model the detailed surface reactions such as ion impingement, neutral adsorption, physical sputtering and chemically enhanced ion etching. Reaction parameters that cannot be measured directly can be extracted or fitted by comparing the model to etch yield data. The results are then compared to the phenomenological model as a test of accuracy. The surface composition taken via x-ray photoelectron spectroscopy is also used as verification before incorporating the results from this model into a feature scale 3D Monte Carlo simulator. Ion incident angle dependence and an elliptical energy deposition model were used to capture the effects of surface morphology on the profile evolution under the bombardment of energetic and directional ions. Obtained profiles are then compared to cross-sectional SEM images of the material systems and display reasonable agreement. This approach thus spans the three major regimes and we applied it to successfully to systems dominated by etching (shallow trench isolation of Si in Cl2/O2 plasmas), deposition (Cu IPVD), and simultaneous etching and deposition (high-k films (HfO2, Al2O3, HfAlO) in Cl2/BCl3 plasmas). 1Martin et al. Journal of Vacuum Science and Technology A 27(2) 2009 2Hsu et al. Journal of Vacuum Science and Technology B. 26 (6) 2008 3Kwon et al. Journal of Vacuum Science and Technology A. 24(5) 2006
    2010 AIChE Annual Meeting; 11/2010
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    ABSTRACT: Multiferroic materials have attracted much attention due to their interesting multifunctional properties and potential applications in future generations of memory devices. Pb(Zr,Ti)O3/CoFe2O4 (PZT/CFO) double-layer thin films were proved to have good magnetoelectric (ME) effect, thus motivating the investigation of three-dimensional and nano-scaled PZT/CFO architecture to increase memory density and optimize multiferroic properties. In this work, mesoporous CFO thin film were formed by evaporation-induced self-assembly with pores of 14 nm in diameter and exhibited ferromagnetism with saturation magnetization of 9x10-4 emu and coercivity of 1200 Oe at room temperature. Ultra-thin PZT films were synthesized by atomic layer deposition at a deposition rate of 0.7 nm/cycle and a 14-nm thick film presented remanent and saturation polarization of 4.3 and 7.9 C/cm2, and a coercive electrical field (Ec) of 1.26 MV/cm. Combining the porous CFO with a uniform and conformal coating of 5-7 nm PZT films, a nano-structured PZT-CFO hybrid material was formed and confirmed by scanning electron microscope (SEM), transmission electron microscope (TEM) and ultraviolet photoelectron spectroscopy (UPS) measurements. To assess multiferroic properties of the PZT/CFO composite, superconducting quantum interference device (SQUID) magnetometry was used. When the samples were measured in-plane, the saturation magnetization was relatively constant at 7.8x10-4 emu after electrical poling at 1kV/cm. While the samples were measured out-of-plane, the saturation magnetization decreased from 9.0x10-4 to 8.5x10-4 emu after electrical poling at 1kV/cm. Polarization voltage (P-V) measurement is underway and so far the promising results indicate ALD enables the synthesis of a PZT-CFO composite with magnetoelectric coupling effect and potential in memory applications.
    2010 AIChE Annual Meeting; 11/2010
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    ABSTRACT: Lithium-ion batteries have drawn much attention for their outstanding performance in portable electronics applications. They also have the potential to function as a power source for micro-systems through engineering of electrodes into 3D architectures based on high aspect ratio pillars. However, to realize this potential, an ultra-thin and highly conformal electrolyte layer is needed to coat the 3D electrode array. The solid electrolyte lithium aluminosilicate (LiAlSiO4), is a promising candidate for this application due to high ionic conductivity along its c-axis resulting from channels formed by the alternating tetrahedra of aluminum-oxygen (Al-O) and silicon-oxygen (Si-O). Atomic layer deposition (ALD) was employed in this work to synthesize thin film lithium aluminosilicate as an electrolyte. The self-limiting characteristic of ALD allows for precise control of thickness and composition of complex oxides and results in a highly conformal and pinhole-free coating suitable in 3D micro-battery applications. The metal precursors used in this work are tetraethyl orthosilicate (TEOS), trimethylaluminum (TMA) and lithium t-butoxide (LTB). These precursors, along with water vapor as the oxidant, were used to deposit SiO2, Al2O3 and Li2O, with the deposition rates in the range of 0.8~2/cycle. The deposition rate of stoichiometric LiAlSiO4 was ~5/cycle. The concentration of each metal element in LixAlySizO thin films is found to correlate closely to ALD cycles and the associated incubation times. The crystalline structures as well as the local environment of the Li-conducting channels are also affected by the ALD cycles and sequences, as indicated by ultraviolet photoelectron spectroscopy (UPS), transmission electron microscopy (TEM) imaging and nuclear magnetic resonance (NMR) analyses. The Li-ion conductivities of ALD LixAlySizO thin films were determined by impedance measurements using a four-point probe setup with contacts made to the film surface. The films have high ion conductivity and low electronic conductivity, the values of which are strongly inf luenced by the lithium content and distribution in the synthesized thin films.
    2010 AIChE Annual Meeting; 11/2010
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    ABSTRACT: The hydrothermal growth of yttrium hydroxide [Y(OH)3] nanotubes (NTs) and the subsequent transformation into yttrium oxide (Y2O3) NTs by thermal annealing were probed by in situ characterization techniques, mainly with synchrotron radiation, to elucidate its reaction mechanism. Upon heating the precursors to 120 °C, the formation of Y(OH)3 NTs was immediately observed, as evident by the diffraction peaks related to the hexagonal phase of Y(OH)3. However, on the basis of X-ray absorption spectroscopic data, the local bonding and ordering began to resemble those of a stable Y(OH)3 crystal after a reaction time of 7 h. Upon annealing of the as-prepared Y(OH)3 NTs, a stable reaction intermediate, YO(OH), with a monoclinic crystal structure is formed at 250 °C. Hence, the dehydration process follows a two-step reaction: Y(OH)3 → YO(OH) → Y2O3; i.e. the elimination of the hydroxyl groups takes two sequential steps, which leads to the formation of Y2O3 NTs.
    The Journal of Physical Chemistry C. 09/2010; 114(41).
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    ABSTRACT: The semiconductor industry will soon be launching 32 nm complementary metal oxide semiconductor (CMOS) technology node using 193 nm lithography patterning technology to fabricate microprocessors with more than 2 billion transistors. To ensure the survival of Moore's law, alternative patterning techniques that offer advantages beyond conventional top-down patterning are aggressively being explored. It is evident that most alternative patterning techniques may not offer compelling advantages to succeed conventional top-down lithography for silicon integrated circuits, but alternative approaches may well indeed offer functional advantages in realising next-generation information processing nanoarchitectures such as those based on cellular, bioinsipired, magnetic dot logic, and crossbar schemes. This paper highlights and evaluates some patterning methods from the Center on Functional Engineered Nano Architectonics in Los Angeles and discusses key benchmarking criteria with respect to CMOS scaling.
    Advanced Materials 02/2010; 22(6):769-78. · 14.83 Impact Factor

Publication Stats

772 Citations
160.14 Total Impact Points

Institutions

  • 2000–2014
    • University of California, Los Angeles
      • Department of Chemical and Biomolecular Engineering
      Los Angeles, California, United States
  • 2005–2008
    • CSU Mentor
      Long Beach, California, United States
  • 1997–1998
    • Massachusetts Institute of Technology
      Cambridge, Massachusetts, United States