Bulletin of the American Physical Society
APS March Meeting 2020
Volume 65, Number 1
Monday–Friday, March 2–6, 2020; Denver, Colorado
Session B27: Applications of Semiconductors, Dielectrics, and Complex Oxides |
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Sponsoring Units: FIAP Chair: Meeghage Perera, National Research Council Room: 404 |
Monday, March 2, 2020 11:15AM - 11:27AM |
B27.00001: Effects of residual stress on MEMS direction-finding sound sensors Meeghage Perera, Renato Rabelo, Fabio Alves, Gamani Karunasiri The hearing mechanism of the fly Ormia Ochracea has been studied and mimicked using micro-electromechanical system (MEMS) technology as an acoustic direction-finding sensor. A typical MEMS sensor consists of two wings connected by a bridge with the entire mechanical structure connected to a substrate. The sensors employed in this work were fabricated on a silicon-on-insulator (SOI) substrate using MEMSCAP’s SOIMUMPS process which found to generate a residual-stress induced curvature on the wings. This reduces the overlap between the wing and substrate comb fingers, which affects the electronic signal output. An in-depth study was performed to understand the stress dependence on geometry and substrate and device configurations. A set of sensors fabricated with different configurations were systematically studied using optical profilometry and scanning electron microscopy. The measured profiles show offsets between the edge of the wings and substrates as high as 40 um for metalized devices and as low as 10 um for non-metallized devices. The curvatures of the sensors were fitted using finite element models to provide the stress values for each configuration and designing parameters to minimize this effect in future designs. |
Monday, March 2, 2020 11:27AM - 11:39AM |
B27.00002: Alloying hexagonal/orthorhombic Ga2O3 with Al2O3 Sierra Seacat, John Lyons, Hartwin Peelaers Ga2O3 is a wide-band-gap semiconductor with promising applications in high-power devices and UV photodetectors. It occurs in several polymorphs, with monoclinic β-gallia the thermodynamically stable phase. Other polymorphs of Ga2O3 can be stabilized as well, but are less studied. The ε- and κ-polymorphs are of interest as they possess ferroelectric properties and exhibit large spontaneous electrical polarizations. |
Monday, March 2, 2020 11:39AM - 11:51AM |
B27.00003: Nanomaterials-based Color-Detection via Machine-Learning Algorithms Davoud Hejazi, Shuangjun Liu, Amirreza Farnoosh, Sarah Ostadabbas, Swastik Kar Some of the major challenges in optical spectrum estimation include the necessity to create an array of thousands of identical photodetectors, or intricate mechanical systems that make the estimation system bulky and expensive. Using the spectral transmittance of an array of 11 solution-processed nanomaterial thin film filters fabricated from two layered semiconducting materials, Molybdenum-Disulfide and Tungsten-Disulfide, we have estimated the wavelength of any incoming light in a wide spectrum range. By applying machine learning techniques we have used the variations in spectral transmittance of nanomaterials as the alternative method for optical spectrum estimation. We have studied the efficacy of various machine learning algorithms including k-nearest neighbors, artificial neural networks, support vector machines, and Bayesian statistics in spectrum estimation problem and identified the key advantages and limitations of each algorithm for real-time applications such as accuracy and speed. Furthermore, we have modeled the temporal drift of filters' spectral transmittance over a period of one year and showed that it is possible to overcome the drift-induced inaccuracies over time using a modeled drift function. |
Monday, March 2, 2020 11:51AM - 12:03PM |
B27.00004: SiGe Devices with High-k Dielectric Gates Jennifer DeMell, Gregory Stephen, Chomani K. Gaspe, Christopher Richardson, Adam Friedman SiGe is an attractive material for future advanced electronic devices desired for beyond Moore’s law high performance computing. In particular, for spintronic devices, it offers extremely high mobilities that can lead to long spin diffusion lengths and a spin--orbit coupling that can be used to control spin relaxation in spin valves—a prerequisite for any spinFET device. Moreover, it is amenable to scaling and is compatible with most commercial device fabrication facilities in foundries. Here, we grow a compressively strained Ge quantum well with relaxed Si0.2Ge0.8 barriers using molecular beam epitaxy. We fabricate devices to determine the basic properties of the films using both charge and spin state variables. We perform a systematic study to create a method of growing high-quality high-k dielectrics (hafnia and alumina) by atomic layer deposition to allow gating of the devices. We present magnetotransport results for both the charge- and spin-based devices from 3-300 K at fields up to 2.5 T. |
Monday, March 2, 2020 12:03PM - 12:15PM |
B27.00005: A bifurcation study of the dynamics of TaO memristors Yuriy Pershin, Valeriy Slipko Pulse-driven memristors (resistance-switching cells) are interesting from the dynamical system point of view. When driven by periodic alternating-polarity pulses, their time-averaged dynamics may converge to fixed-point attractors [1]. Recently, we have shown that the maximum number of stable fixed points in a broad range of popular memristor models is one [2]. Here, we analyze the pulse-driven dynamics of tantalum oxide memristors using a sophisticated device model developed in Ref. [3]. Our main finding is the identification of a driving regime when two stable fixed points exist simultaneously [4]. To the best of our knowledge, such bistability is identified in a single memristor for the first time. Bifurcation curves separating pulse parameter regions corresponding to 0, 1, or 2 stable fixed points have been found analytically. Our results can be tested experimentally and are expected to be useful in future memristor circuit designs. |
Monday, March 2, 2020 12:15PM - 12:27PM |
B27.00006: Parametric Coupling in Aluminum Nitride Lamb Wave Devices Through a Nonlinear Elastic Modulus Joseph Schneider, Ting Lu, Sidhant Tiwari, Xiating Zou, Ajit Mal, Robert Candler, Yuanxun Ethan Wang, Greg P Carman Parametric coupling was intensely studied in the 1950s where a time varying circuit parameter (i.e. capacitance or inductance) is used to provide frequency conversion, allowing energy supplied at one frequency to be converted to another. The main advantage of this process is its low noise characteristic and is a promising step forward for low noise radio frequency (RF) devices. However, the realization of small devices relying on a time varying circuit parameter is difficult for lower frequency applications (100MHz – 1GHz) due to the long electromagnetic wavelength. In this research, Aluminum Nitride (AlN) Lamb wave devices are investigated as an option for parametric coupling in acoustic waves, significantly reducing the size of devices in the desired frequency range. |
Monday, March 2, 2020 12:27PM - 12:39PM |
B27.00007: Evidence for ferroelectric polarons in lead halide perovskites Xiaoyang Zhu Lead halide perovskites are characterized by dielectric responses and phonon dynamics resembling those of liquids. We show that the dielectric function in the THz region in this class of materials may lead to dynamic and local ordering of polar nano domains by an extra electron or hole, resulting a quasiparticle which we call a ferroelectric large polaron, a concept similar to solvation in chemistry. Compared to a conventional large polaron, the collective nature of polarization in a ferroelectric large polaron may give rise to order(s)-of-magnitude larger reduction in the Coulomb potential. We show that the shape of a ferroelectric polaron resemble that of a Belgian waffle. Using two-dimensional coherent phonon spectroscopy, we directly probe the energetics and local phonon responses of the ferroelectric large polarons. We find that that electric field from a nascent e-h pair drives the local transition to a hidden ferroelectric order on picosecond time scale. The ferroelectric or Belgian waffle polarons may explain the defect tolerance and low recombination rates of charge carriers in lead halide perovskites, as well as providing a design principle of the “perfect” semiconductor for optoelectronics. |
Monday, March 2, 2020 12:39PM - 12:51PM |
B27.00008: Surface structure and electronics of all-inorganic halide perovskites CsPbI3: A first-principles study of surface reconstructions Azimatu Seidu, Patrick Rinke, Jingrui Li
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Monday, March 2, 2020 12:51PM - 1:03PM |
B27.00009: Local Magnetic Field Effect on InSb Nanowire Devices Yifan Jiang, Vince van de Sande, Eline de Jong, Sasa Gazibegovic, Ghada Badawy, Roy Op het Veld, Erik Bakkers, Sergey M Frolov Devices based on InSb nanowires are platforms for various of experiments, including quantum point contacts, quantum dots and Majorana zero modes. In most of such experiments, when a magnetic field is necessary, a large superconducting solenoid magnet is used to produce a global field. However, this homogenous magnetic field may limit device architecture. Instead of producing a global magnetic field, we can produce magnetic field locally by placing micro-magnets beside nanowire devices. In our experiment, we fabricate CoFe micromagnets next to InSb nanowire devices which also have Ti/Au ohmic contacts. Hysteretic magnetoresistance with sharp switches is observed, indicating penetration of local magnetic field from CoFe micromagnets into the nanowire. We also estimate that the magnitude of the local magnetic field into the InSb nanowire is several tens of mT. This successful demonstration of local magnetic field effect may bring a new approach for scalable topological computing. |
Monday, March 2, 2020 1:03PM - 1:15PM |
B27.00010: Comparison of spin photocurrent in devices based on in-plane or out-of-plane magnetized CoFeB spin detectors Pierre Renucci, Xiaodi Xue, Laipan Zhu, Wei Huang, Yu Liu, Yang Zhang, Xiaolin Zeng, Jing Wu, Bo Xu, Zhanguo Wang, Yonghai Chen, Weifeng zhang, Xavier Marie, Yuan LU
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Monday, March 2, 2020 1:15PM - 1:27PM |
B27.00011: Characterization of quantum tunneling devices by controlled current pulses Edgar J Patino, Leonardo Rios E
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Monday, March 2, 2020 1:27PM - 1:39PM |
B27.00012: Topology-optimized Metal-Semiconductor Hybrid Structures to obtain Optimal Extraordinary Magentoresistance Debanik Das, Sathwik Bharadwaj, L Ramdas Ram-Mohan Semiconductor wafer with metallic inclusions generates extraordinary magnetoresistance (EMR) response [1]. This effect has found applications in high sensitivity magnetic sensors, and smaller magnetic read heads. Since its inception, efforts have been made to increase magnetoresistance through different choices of materials, by altering location of contacts, filling factor, and shape of the device. However, a systemic study to optimize topology of the metallic inclusions has not been considered in the literature. Here, we employ a topology optimization scheme based on the level set function. For evolution of the level set curve, topological derivative is used as the sensitivity term in the Hamilton-Jacobi equation. In contrast to conventional homogenization based methods, this optimization scheme will not produce gray region in the metal-semiconductor boundary. We are also able to control the complexity of the structure to design realistic geometries for fabrication of the physical prototype. The optimized geometry is robust and independent of the initial configuration. When combined with material optimization, this algorithm manifests a potential for significant improvements in EMR technology. |
Monday, March 2, 2020 1:39PM - 1:51PM |
B27.00013: In4Se3 (001) surface termination and Schottky-barrier formation Archit Dhingra, Pavlo V. Galiy, Lu Wang, Taras M. Nenchuk, Andrew J. Yost, Wai-Ning Mei, Peter A Dowben In4Se3 (001) is a novel n-type semiconductor with great potential for 2D material phototransistors and beyond CMOS electronics. X-ray photoemission spectroscopy (XPS) measurements indicate that In4Se3 (001) system terminates in In (and not Se). These results disagree with density functional theory, which indicates that the Se termination of In4Se3 (001) is more stable. The interface between In4Se3 (001) and evaporated Au indicates toward the existence of Schottky barrier. This is very different from the interface between Au and TiS3 (001), which exhibits Ohmic behavior. Additionally, the shift in binding energy (due to a barrier height) shows up only in one of the In core level photoemission components that is nearest to the interface. |
Monday, March 2, 2020 1:51PM - 2:03PM |
B27.00014: Characteristics of β-Ga2O3 2D-nanoleaf and 1D-nanowire structures and their resistive switching performance Chandrasekar Sivakumar, Gang-Han Tsai, Mon-shu Ho Resistive memory is one of the promising next generation nonvolatile memories with advantages over other emerging nonvolatile memories like DRAM, PCRAM, CBRAM etc. Dielectric thin films as the resistive switching material have been studied extensively through the scientific community. In this study, we have taken advantage of controlled electron flow in 2D and 1D materials to study the resistive switching. High-density single crystalline β-Ga2O3 2D-nanoleafs and 1D nanowires on Si (100) substrate are grown by vapor-liquid-solid growth technique. The structural features are explored by SEM, TEM and XRD analysis. The elemental compositions and binding characteristics are confirmed by the EDS spectrum from FESEM and TEM analysis and XPS respectively. The photoelectrical property is studied by Raman spectroscopy and absorption spectroscopy. Here we have compared the resistive switching performance of a single 2D β-Ga2O3 nanoleaf and 1D β-Ga2O3 nanowire ReRAM devices. The switching mechanism of both 1D and 2D nanostructures are governed by the oxygen migration between two electrodes by the formation and rupture of conducting filaments. |
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