Bulletin of the American Physical Society
APS March Meeting 2020
Volume 65, Number 1
Monday–Friday, March 2–6, 2020; Denver, Colorado
Session D27: Electronic Thin Film Devices and Nanotechnology |
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Sponsoring Units: FIAP DCMP Chair: Tzu-Ming Lu, Sandia National Laboratories Room: 404 |
Monday, March 2, 2020 2:30PM - 2:42PM |
D27.00001: Development of a high-k gate stack for atomic-precision advanced manufacturing Tzu-Ming Lu, Evan Anderson, DeAnna Campbell, Michael Marshall, Ping Lu, Scott W Schmucker, Lisa A Tracy, Mitchell Robison, Reza Arghavani, Leon N Maurer, Andrew Baczewski, Daniel R Ward, Shashank Misra Atomic-precision advanced manufacturing (APAM) is a process in which a scanning tunneling microscope is used to create atomically precise conducting channels in Si. Gating of APAM devices is typically achieved by patterning electrical gates in the same plane as the channel. Higher transconductance could be achieved by adopting a vertical metal-oxide-semiconductor gate stack. Here we report on the development of such a gate stack incorporating high-k dielectrics. The process flow is designed to be APAM compatible with an ultra-low thermal budget. We evaluate the quality of the gate stack using capacitance-voltage measurements. This work was supported by the Laboratory Directed Research and Development Program at Sandia National Laboratories and was performed, in part, at the Center for Integrated Nanotechnologies, a U.S. DOE, Office of Basic Energy Sciences user facility. Sandia National Laboratories is a multimission laboratory managed and operated by National Technology & Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525. The views expressed in the article do not necessarily represent the views of the DOE or the U.S. Government. |
Monday, March 2, 2020 2:42PM - 2:54PM |
D27.00002: Phase Controlling in HfO2 Bulk Single Crystal Xianghan Xu, Fei-Ting Huang, Sang-Wook Cheong Contingent upon the miniaturization of semiconductor circuits, high-dielectric hafnium oxide (HfO2) serves an alternative to silicon oxide. Surprisingly, the continued scaling comes with unexpected ferroelectricity at nanoscale HfO2 in both pure and doped forms. These unusual findings are attributed to polymorphic nature including monoclinic, tetragonal, and orthorhombic phases and phase transitions in thin films, which is a big challenge in bulk crystal growth. Here, we show that utilizing the state-of-the-art laser floating zone technique allows the stabilization of the metastable phases at room temperature and pressure. We investigate the evolution of structural phases with various thermal treatments and doping. A comprehensive study on the structural transition pathway using in-situ transmission electron microscope (TEM) will be discussed. Our results provide insights for an alternative route for phase controlling of HfO2 and the comparisons with thin films. |
Monday, March 2, 2020 2:54PM - 3:06PM |
D27.00003: The effect of air-anneal on two-level tunneling systems of ion-beam sputtered amorphous SiO2 Xiao Liu, Matthew Abernathy, Thomas Metcalf, Massimo Granata, Lorenzo Mereni, Alex Amato, Christophe Michel, Gianpietro Cagnoli Reducing mechanical loss, or internal friction, in amorphous dielectric coating materials is practically important in many present-day applications, such as mirror coatings of gravitational-wave detectors or dielectric insulating layer in superconducting quantum bits. It is known that mechanical loss is dominated by atomic tunneling through potential barriers of double-well potentials below ~10 K and by thermal activation over the same potential barrier landscape. It has been found that extended air anneal reduces near-room temperature mechanical loss of ion-beam sputtered amorphous SiO2. We measured elastic properties of ion-beam sputtered amorphous SiO2 from 0.3 K to room temperature that includes internal friction, shear modulus and the relative change of speed of sound, and found that internal friction increases slightly accompanied by a large drop of thermal activation peak at higher temperatures. We discuss possible mechanisms for our observations. |
Monday, March 2, 2020 3:06PM - 3:18PM |
D27.00004: Demonstration of two-dimensional hole gases (2DHG) in strained GeSn quantum wells Chia-Tse Tai, Cheng-Yu Lin, Chia-You Liu, Tz-Ming Wang, Charles Harris, Tzu-Ming Lu, Jiun-Yun Li In this work, capacitively induced two-dimensional hole gases in undoped Ge/GeSn heterostructures were demonstrated. Ge/GeSn heterostructures with Sn fractions of 6%, 9% and 11% were grown by chemical vapor deposition with surface roughness below 3 nm. Hall bar devices were fabricated and characterized at 4 K. Density saturation was observed and the highest mobility was 1.9x104 cm2/Vs. The dominant scattering mechanism is likely background impurity scattering. Shubnikov-de Haas oscillations and the quantum Hall effect were observed at B > 1 T, indicating high-quality material growth of Ge/GeSn heterostructures. Effective masses were extracted by the temperature-dependent SdH oscillations. |
Monday, March 2, 2020 3:18PM - 3:30PM |
D27.00005: High sensitivity neutron detectors based on hexagonal boron nitride epilayers Avisek Maity, Samuel Grenadier, Jing Li, Jingyu Lin, Hongxing Jiang Hexagonal boron nitride (h-BN) has emerged as a promising material for realizing high efficiency solid-state thermal neutron detectors. Here, we report the epitaxial growth of thick h-10BN (10B enriched) epilayers and demonstration of thermal neutron detectors with a record high detection efficiency. To increase the overall detection sensitivity, we have explored strategies in material growth and device processing to reduce the detector’s dark current, capacitance, and surface recombination field and realized h-10BN detectors from 100 µm thick freestanding wafers with a detection area as large as 1 cm2 and a detection efficiency as high as 59%. We discuss the detail design and implementation of horizontal h-10BN detectors to overcome the detrimental effects associated with increased dark current, capacitance, and surface recombination with increasing detector size, through reduction in metal contact area of the detector and utilization of superior lateral transport properties of h-BN. This work lays the foundation for achieving highly sensitive large h-10BN neutron detectors for practical applications. |
Monday, March 2, 2020 3:30PM - 3:42PM |
D27.00006: Defect effects on Electron Magneto-Transport in Quantum Wells Danhong Huang, Andrii Iurov, Fei Gao, Godfrey Gumbs The point-defect effects on the electron magneto-transport in a multiple quantum-well system are investigated by employing a many-body theory. By working within the ladder approximation, our theory takes into account the local-field vertex correction to a bare polarization function of electrons. Moreover, both intralayer and interlayer screening to defect-electron interactions are included within the random-phase approximation. Furthermore, by studying defect charging dynamics, both capture and relaxation times of a point defect, as well as captured density of electrons, are computed as functions of temperature, electron density and different types of point defects. Finally, numerically calculated defect effects on energy-relaxation and momentum-relaxation times of are presented and analyzed for various defect and electron densities and different temperatures as well. |
Monday, March 2, 2020 3:42PM - 3:54PM |
D27.00007: Atomistic Simulations of the Cold Source Field-Effect Transistor for Sub-60 mV/decade Switching Raphaël Prentki, Mohammed Harb, Hong Guo Sub-60 mV/decade subthreshold swing (S) transistors have been the object of considerable research efforts due to their low power dissipations. The cold source field-effect transistor (CSFET) achieves low S by suppressing thermionic emission in the OFF-state through source density-of-states engineering. This device has thus far only been investigated by simulations based on effective mass, k.p, and ballistic approximations. We report the first simulations of CSFETs based on combining the nonequilibrium Green’s functions (NEGF) formalism with the tight-binding (TB) method, thereby capturing the atomistic details of the devices under nonequilibrium conditions. Specifically, we consider gate-all-around Silicon nanowire CSFETs grown in [100], [110], and [111] with diameters ranging from a few Å to a few nm. We find that vacancies and surface roughness have little influence on the performance of the device, which maintains a low S even in the presence of elastic scattering. Finally, we present both n-type and p-type CSFETs, thus substantiating the compatibility of CSFETs with complementary metal–oxide–semiconductor (CMOS) technology. |
Monday, March 2, 2020 3:54PM - 4:06PM |
D27.00008: Looking Back to Look Forward: How scarcity affects electronics cost and drives material research Samantha Reese, Alberta Carpenter, Robin Burton Typically discussions of electronics focuses on high value semiconductor products. However, without commoditized components such as resistors and capacitors and materials such as printed circuit boards and soldier, electronic devices are not possible. As Moore’s Law enables the internet of things (IOT) and allows data to become even more ubiquitous, the consumer electronics market is projected to experience an annual growth rate of 11.6% reaching $528 billion in 2023. This means more components are needed. Case studies will be presented showing how electronics manufacturing volume effects the raw material cost. An analysis of materials needed for commoditized component manufacturing will be shown, it will identify raw materials that could either cause significant cost increases to or even interrupt the component supply chain. The information can then be utilized to direct research into substitution materials or to suggest process improvement opportunities. |
Monday, March 2, 2020 4:06PM - 4:18PM |
D27.00009: Angular Characterization of Magneto Optical Kerr-Effect by Ellipticity Modulation in Ultrathin Samples Fernando Ramiro-Manzano, Jaume Meseguer-Sánchez, Fernando Cantos-Prieto, Efren Navarro-Moratalla Magnetism in 2D materials has become of paramount interest in the scientific community because of overcoming the limitations of the Mermin-Wagner theory, nevertheless, new puzzling questions have arisen. Establishing the thickness frontier between bulk ferromagnetism and few-layer antiferromagnetism or the determination of the spin model that the 2D magnets follow are some of the current unsolved questions. One of the most sensitive techniques for characterizing the magnetism is the polarization changes of ellipticity-modulated light when interacts with a magnetic material. This technique permits to characterize both the Kerr-rotation and magneto-circular dichroism with a sensitivity bellow 100 µrad. Here, we will show the peculiarities of the experiments and simulations of the angular response of Van der Waalls magnetic materials. In particular, the Fourier plane response is acquired and compared with the simulation of the magneto-optical behavior. The fit results could allow extracting important parameters such as the spin orientation. |
Monday, March 2, 2020 4:18PM - 4:30PM |
D27.00010: Designing and characterizing rare-earth upconverting nanoparticles as nanoNewton mechanical sensors. Claire McLellan, Stefan Fischer, Chris Siefe, Jason Casar, Dayne Swearer, Masashi Fukuhara, Miriam B. Goodman, Jennifer A. Dionne Non-invasive nanoscale mechanical force sensors will enable the monitoring of nanoNewton-scale forces in biological and condensed matter systems. Due to their near-infrared excitation with visible emission and robust host lattices, rare-earth upconverting nanoparticles (UCNPs) are a promising technology for mechanical force sensing. When engineered correctly, UCNPs exhibit a ratiometric color response to applied pressure but maintaining brightness high enough to detect this ratiometric color change at the single-particle level remains an outstanding challenge in the field. To create bright and force responsive particles, we explore alkaline earth host lattices (CaLuF, SrLuF, BaLuF). All particles studied are sub-15nm in diameter, core-shell, and are doped with 30% Yb3+ and 2.9% Er3+. Ensemble measurements with a diamond anvil cell yield a red-to-green intensity ratio (IR/IG) pressure responses of 20 ± 1.2, 16.2 ± 0.5, 12.7 ± 0.8, and 40 ± 4 % (IR/IG)/GPa for CaLuF, SrLuF, BaLuF, and NaYF4, the control sample, respectively. We find that SrLuF-based nanoparticles respond to mechanical pressures changes of 37 MPa or 27 nN of force. Using a custom confocal-AFM microscope, we explore the brightness of single UCNPs and are developing techniques to explore their force sensitivity. |
Monday, March 2, 2020 4:30PM - 4:42PM |
D27.00011: Porous Carbon Nanotube Ring Resonators for Gas Sensing Application David McKenna, Henry Davis, RJ Cass, Richard Vanfleet, Robert Davis Using the carbon nanotube templated micro-fabrication (CNT-M) method we have formed and characterized porous micro-mechanical ring resonators for gas sensing applications. The tunable porosity of the CNT structures lends itself to high surface area to volume ratios. In the resonator, a high surface area to mass ratio coupled with a high quality factor (Q) can enable detection of gasses at very low concentrations. The gas concentration detection limit is proportional to the inverse of the Q of the resonator. Building on previous work with micro-cantilevers, here we present results of in-plane ring resonators designed to reduce clamping and thermoelastic losses. This in-plane mode has the added advantage of being less sensitive to manufacturing variations in the height of the resonator. We present our work characterizing the gas and time response of these resonators. |
Monday, March 2, 2020 4:42PM - 4:54PM |
D27.00012: Role of dimensionality on thermodynamic properties in layered sulfides Nathan Koocher, James Rondinelli Understanding thermal expansion of materials helps in assessing the capability, performance, and lifetime of materials operating in variable thermal conditions. Previously Ca3Ti2O7 with the layered Ruddlesden-Popper (RP) structure (n=2 member of An+1BnO3n+1) was found to exhibit pressure-tunable negative thermal expansion (NTE) and a pressure-independent softening of the bulk modulus due to a quasi-two-dimensional vibration [Huang et al, Phys. Rev. Lett. 117, 115901 (2016)], whereas RP strontium titanates did not exhibit NTE [Huang et al, Chem. Mater. 30, 7100 (2018)]. Here, we evaluate structural, lattice dynamical, and thermodynamic properties of the barium zirconium sulfide family with layer thickness n=1,2, and ∞ using the self-consistent quasi-harmonic approximation within density functional theory. We formulate layer thickness dependent models of the anharmonic lattice properties and discuss how they may be used for design of thermal expansion coefficients in other chemistries. |
Monday, March 2, 2020 4:54PM - 5:06PM |
D27.00013: Elastic Constants of Boron Arsenide and Boron Phosphide Crystals Sushant Mahat, Sheng Li, Hanlin Wu, Pawan Koirala, Bing Lv, David Cahill We report experimental results for picosecond ultrasonics (PU) studies of boron arsenide and boron phosphide crystals with zinc blend structure. These materials have coefficients of thermal expansion similar to commonly used semiconductors like Si and GaAs, and the synthesis of BAs and BP single crystals with thermal conductivity as high as 1000 and 540 Wm-1K-1 respectively has made them into promising materials for thermal management applications. Using PU, we measure Brillouin scattering frequencies and calculate longitudinal and shear velocities along several directions of the BAs and BP single crystals. The crystal directions are determined using electron backscattering diffraction and associated Christoffel equations are used to solve for the elastic constants of the crystals. We report C11, C12, and C44 values of 289.4, 113.5 and 159.0 GPa for BAs and 310, 87, and 160 GPa for BP, respectively. Furthermore, we also demonstrate the utility of PU in studying optical and acoustic attenuation in these crystals. The elastic constants and the attenuation measurements will help to predict thermal transport behavior in these materials. |
Monday, March 2, 2020 5:06PM - 5:18PM |
D27.00014: Microscopic model for contact electrification between solids and fluids Morten Willatzen, Lok Chong Lew Yan Voon, Zhong Lin Wang Triboelectric charge transfer between materials is a well-known phenomenon since more than 2000 years that still causes dispute. Recent experimental evidence suggests electron transfer to be the main mechanism for contact electrification between dielectrics and metals, and the electron transfer is specified by the material bandstructures and Fermi levels [1]. We present a new microscopic formalism based on a tight-binding Hamiltonian to describe charge transfer between two materials. The model captures charge transfer dynamics on a femtosecond scale, reveals the influence of Coulomb interactions for charge transfer oscillations, and is able to predict charge transfer differences between materials whether structured or disordered solids and fluids. We demonstrate that charge transfer between fluids and solids is more effective than between two solids, that charge transfer between two similar materials is possible, and shed light on the differences between metal-dielectric and dielectric-dielectric contact electrification. |
Monday, March 2, 2020 5:18PM - 5:30PM |
D27.00015: Nanotube-Templated Growth of Transition Metal Dichalcogenide Nanoribbons Derek Popple, Scott Meyer, Jeffrey D. Cain, Alex Zettl Due to their sizable bandgap and layer-dependent properties, the transition metal dichalcogenides (TMDs) are of interest for a variety of electronic and optoelectronic applications.1 While much research in the field of 2D materials has focused on the emergent properties as a result of confinement to two dimensions, further confinement into quasi-one-dimensional nanoribbons is expected to provide a further handle for tuning the electronic structure.2,3 In this work, we have employed a bottom-up gas-phase synthesis within carbon nanotubes to template the growth of TMD nanoribbons. By growing the materials within nanotubes we can create nanoribbons with variety of widths. The nanotubes also provide protection from degradation due to oxidation or solvents enabling the facile handling and study of air-sensitive materials. |
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