1
|
Zhang Y, Wang C, Wu X. Review of electrical stimulus methods of in situ transmission electron microscope to study resistive random access memory. NANOSCALE 2022; 14:9542-9552. [PMID: 35762914 DOI: 10.1039/d2nr01872a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Resistive random access memory (RRAM) devices have been demonstrated to be a promising solution for the implementation of a neuromorphic system with high-density synapses due to the simple device structure, nanoscale dimension, high switching speed, and low power consumption. Various electrical stimuli applied to RRAM devices could cause various working modes of the bionic synapses. The application of RRAM devices needs to understand the micromechanism of the resistive switching process, which is inseparable from advanced characterization techniques. In situ transmission electron microscopy (TEM) with high-resolution imaging and versatile external fields plays an important role in the static characterization and dynamic manipulation of nanoscale devices. Focused on in situ TEM techniques, this review article introduces in situ TEM setups and the corresponding sample fabrication process for RRAM research. Then, the electrical stimulating methodologies including pulse and direct current voltage applied to RRAM are introduced, followed by the summary of electron holography to characterize the electrical potential distribution. By applying various electrical stimuli to the RRAM samples, the working mode of bionic synapses could be changed according to the requirement. Finally, the outlook of the RRAM study with in situ TEM is proposed. This review demonstrates the electrical stimulus capability of in situ TEM to understand the physical mechanism of various types of RRAM devices.
Collapse
Affiliation(s)
- Yewei Zhang
- In Situ Devices Center, School of Communication and Electronic Engineering, East China Normal University, Shanghai 200241, China.
| | - Chaolun Wang
- In Situ Devices Center, School of Communication and Electronic Engineering, East China Normal University, Shanghai 200241, China.
| | - Xing Wu
- In Situ Devices Center, School of Communication and Electronic Engineering, East China Normal University, Shanghai 200241, China.
| |
Collapse
|
2
|
Tyukalova E, Vimal Vas J, Ignatans R, Mueller AD, Medwal R, Imamura M, Asada H, Fukuma Y, Rawat RS, Tileli V, Duchamp M. Challenges and Applications to Operando and In Situ TEM Imaging and Spectroscopic Capabilities in a Cryogenic Temperature Range. Acc Chem Res 2021; 54:3125-3135. [PMID: 34339603 DOI: 10.1021/acs.accounts.1c00078] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
ConspectusIn this Account, we describe the challenges and promising applications of transmission electron microscopy (TEM) imaging and spectroscopy at cryogenic temperatures. Our work focuses on two areas of application: the delay of electron-beam-induced degradation and following low-temperature phenomena in a continuous and variable temperature range. For the former, we present a study of LiMn1.5Ni0.5O4 lithium ion battery cathode material that undergoes electron beam-induced degradation when studied at room temperature by TEM. Cryogenic imaging reveals the true structure of LiMn1.5Ni0.5O4 nanoparticles in their discharged state. Improved stability under electron beam irradiation was confirmed by following the evolution of the O K-edge fine structure by electron energy-loss spectroscopy. Our results demonstrate that the effect of radiation damage on discharged LiMn1.5Ni0.5O4 was previously underestimated and that atomic-resolution imaging at cryogenic temperature has a potential to be generalized to most of the Li-based materials and beyond. For the latter, we present two studies in the imaging of low-temperature phenomena on the local scale, namely, the evolution of ferroelectric and ferromagnetic domains walls, in BaTiO3 and Y3Fe5O12 systems, respectively, in a continuous and variable temperature range. Continuous imaging of the phase transition in BaTiO3, a prototypical ferroelectric system, from the low-temperature orthorhombic phase continuously up to the centrosymmetric high-temperature phase is shown to be possible inside a TEM. Similarly, the propagation of domain walls in Y3Fe5O12, a magnetic insulator, is studied from ∼120 to ∼400 K and combined with the application of a magnetic field and electrical current pulses to mimic the operando conditions as in domain wall memory and logic devices for information technology. Such studies are promising for studying the pinning of the ferroelectric and magnetic domains versus temperature, spin-polarized current, and externally applied magnetic field to better manipulate the domain walls. The capability of combining operando TEM stimuli such as current, voltage, and/or magnetic field with in situ TEM imaging in a continuous cryogenic temperature range will allow the uncovering of fundamental phenomena on the nanometer scale. These studies were made possible using a MEMS-based TEM holder that allowed an electron-transparent sample to be transferred and electrically contacted on a MEMS chip. The six-contact double-tilt holder allows the alignment of the specimen into its zone axis while simultaneously using four electrical contacts to regulate the temperature and two contacts to apply the electrical stimuli, i.e., operando TEM imaging. This Account leads to the demonstration of (i) the high-resolution imaging and spectroscopy of nanoparticles oriented in the desired [110] zone-axis direction at cryogenic temperatures to mitigate the electron beam degradation, (ii) imaging of low-temperature transitions with accurate and continuous control of the temperature that allowed single-frame observation of the presence of both the orthorhombic and tetragonal phases in the BaTiO3 system, and (iii) magnetic domain wall propagation as a function of temperature, magnetic field, and current pulses (100 ns with a 100 kHz repetition rate) in the Y3Fe5O12 system.
Collapse
Affiliation(s)
| | | | - Reinis Ignatans
- Institute of Materials, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
| | | | | | - Masaaki Imamura
- Department of Electrical Engineering, Fukuoka Institute of Technology, Fukuoka 811-0295, Japan
| | - Hironori Asada
- Graduate School of Sciences and Technology for Innovation, Yamaguchi University, Ube 755-8611, Japan
| | - Yasuhiro Fukuma
- Department of Physics and Information Technology, Kyushu Institute of Technology, Iizuka 820-8502, Japan
- Research Center for Neuromorphic AI Hardwares, Kyushu Institute of Technology, Kitakyushu 808-0196, Japan
| | | | - Vasiliki Tileli
- Institute of Materials, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
| | | |
Collapse
|
3
|
Yamamoto K, Anada S, Sato T, Yoshimoto N, Hirayama T. Phase-shifting electron holography for accurate measurement of potential distributions in organic and inorganic semiconductors. Microscopy (Oxf) 2021; 70:24-38. [PMID: 33044557 DOI: 10.1093/jmicro/dfaa061] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Revised: 09/28/2020] [Accepted: 10/09/2020] [Indexed: 11/14/2022] Open
Abstract
Phase-shifting electron holography (PS-EH) is an interference transmission electron microscopy technique that accurately visualizes potential distributions in functional materials, such as semiconductors. In this paper, we briefly introduce the features of the PS-EH that overcome some of the issues facing the conventional EH based on Fourier transformation. Then, we present a high-precision PS-EH technique with multiple electron biprisms and a sample preparation technique using a cryo-focused-ion-beam, which are important techniques for the accurate phase measurement of semiconductors. We present several applications of PS-EH to demonstrate the potential in organic and inorganic semiconductors and then discuss the differences by comparing them with previous reports on the conventional EH. We show that in situ biasing PS-EH was able to observe not only electric potential distribution but also electric field and charge density at a GaAs p-n junction and clarify how local band structures, depletion layer widths and space charges changed depending on the biasing conditions. Moreover, the PS-EH clearly visualized the local potential distributions of two-dimensional electron gas layers formed at AlGaN/GaN interfaces with different Al compositions. We also report the results of our PS-EH application for organic electroluminescence multilayers and point out the significant potential changes in the layers. The proposed PS-EH enables more precise phase measurement compared to the conventional EH, and our findings introduced in this paper will contribute to the future research and development of high-performance semiconductor materials and devices.
Collapse
Affiliation(s)
- Kazuo Yamamoto
- Nanostructures Research Laboratory, Japan Fine Ceramics Center, 2-4-1 Mutsuno, Atsuta-ku, Nagoya, Aichi, 456-8587, Japan.,Faculty of Science and Engineering, Iwate University, 4-3-5 Ueda, Morioka, Iwate, 020-8551, Japan
| | - Satoshi Anada
- Nanostructures Research Laboratory, Japan Fine Ceramics Center, 2-4-1 Mutsuno, Atsuta-ku, Nagoya, Aichi, 456-8587, Japan
| | - Takeshi Sato
- Nano-Technology Solution Business Group, Hitachi High-Tech Corporation, 1040, Ichige, Hitachinaka-shi, Ibaraki, 312-0033, Japan
| | - Noriyuki Yoshimoto
- Faculty of Science and Engineering, Iwate University, 4-3-5 Ueda, Morioka, Iwate, 020-8551, Japan
| | - Tsukasa Hirayama
- Nanostructures Research Laboratory, Japan Fine Ceramics Center, 2-4-1 Mutsuno, Atsuta-ku, Nagoya, Aichi, 456-8587, Japan
| |
Collapse
|
4
|
Nanosecond electron holography by interference gating. Ultramicroscopy 2019; 206:112824. [PMID: 31401353 DOI: 10.1016/j.ultramic.2019.112824] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2019] [Revised: 07/19/2019] [Accepted: 07/26/2019] [Indexed: 11/24/2022]
Abstract
The interference gating is a novel method for robust time-resolved electron holographic measurements by directly switching the interference. Here, a new arrangement is presented in which a biprism in the condenser aperture as a fast electric phase shifter is used to control the interference pattern. High-frequency stimulation of the electric phase shifter in the gigahertz range are performed and observed via electron holography, proving the feasibility of interference gating in the upper picosecond range. Despite the bandwidth limitation of 180 MHz of the current signal generator, a time resolution of 100 ns is achieved through forward correction of the control signal. With this time resolution, it is already possible to measure the transient response of the biasing holder system. Our method paves the way towards a closer look on fast dynamic processes with high temporal and spatial resolution.
Collapse
|
5
|
Anada S, Yamamoto K, Sasaki H, Shibata N, Matsumoto M, Hori Y, Kinugawa K, Imamura A, Hirayama T. Accurate measurement of electric potentials in biased GaAs compound semiconductors by phase-shifting electron holography. Microscopy (Oxf) 2019; 68:159-166. [PMID: 30452667 DOI: 10.1093/jmicro/dfy131] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2018] [Revised: 10/23/2018] [Accepted: 11/11/2018] [Indexed: 11/13/2022] Open
Abstract
The innate electric potentials in biased p- and n-type GaAs compound semiconductors and the built-in potential were successfully measured with high accuracy and precision by applying in situ phase-shifting electron holography to a wedge-shaped GaAs specimen. A cryo-focused-ion-beam system was used to prepare the 35°-wedge-shaped specimen with smooth surfaces for a precise measurement. The specimen was biased in a transmission electron microscope, and holograms with high-contrast interference fringes were recorded for the phase-shifting method. A clear phase image around the p-n junction was reconstructed even in a thick region (thickness of ~700 nm) at a spatial resolution of 1 nm and precision of 0.01 rad. The innate electric potentials of the unbiased p- and n-type layers were measured to be 12.96 ± 0.17 V and 14.43 ± 0.19 V, respectively. The built-in potential was determined to be 1.48 ± 0.02 V. In addition, the in situ biasing measurement revealed that the measured electric-potential difference between the p and n regions changed by an amount equal to the voltage applied to the specimen, which indicates that all of the external voltage was applied to the p-n junction and that no voltage loss occurred at the other regions.
Collapse
Affiliation(s)
- Satoshi Anada
- Nanostructures Research Laboratory, Japan Fine Ceramics Center, 2-4-1 Mutsuno, Atsuta-ku, Nagoya, Japan
| | - Kazuo Yamamoto
- Nanostructures Research Laboratory, Japan Fine Ceramics Center, 2-4-1 Mutsuno, Atsuta-ku, Nagoya, Japan
| | - Hirokazu Sasaki
- Advanced Technologies Research and Development Laboratories, Furukawa Electric Co. Ltd, 2-4-3 Okano, Nishi-ku, Yokohama, Japan
| | - Naoya Shibata
- Nanostructures Research Laboratory, Japan Fine Ceramics Center, 2-4-1 Mutsuno, Atsuta-ku, Nagoya, Japan.,Institute of Engineering Innovation, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo, Japan
| | - Miko Matsumoto
- Nanostructures Research Laboratory, Japan Fine Ceramics Center, 2-4-1 Mutsuno, Atsuta-ku, Nagoya, Japan
| | - Yujin Hori
- Advanced Technologies Research and Development Laboratories, Furukawa Electric Co. Ltd, 2-4-3 Okano, Nishi-ku, Yokohama, Japan
| | - Kouhei Kinugawa
- Advanced Technologies Research and Development Laboratories, Furukawa Electric Co. Ltd, 2-4-3 Okano, Nishi-ku, Yokohama, Japan
| | - Akihiro Imamura
- Advanced Technologies Research and Development Laboratories, Furukawa Electric Co. Ltd, 2-4-3 Okano, Nishi-ku, Yokohama, Japan
| | - Tsukasa Hirayama
- Nanostructures Research Laboratory, Japan Fine Ceramics Center, 2-4-1 Mutsuno, Atsuta-ku, Nagoya, Japan
| |
Collapse
|
6
|
McCartney MR, Dunin-Borkowski RE, Smith DJ. Quantitative measurement of nanoscale electrostatic potentials and charges using off-axis electron holography: Developments and opportunities. Ultramicroscopy 2019; 203:105-118. [PMID: 30772077 DOI: 10.1016/j.ultramic.2019.01.008] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Revised: 12/27/2018] [Accepted: 01/21/2019] [Indexed: 12/01/2022]
Abstract
Off-axis electron holography has evolved into a powerful electron-microscopy-based technique for characterizing electromagnetic fields with nanometer-scale resolution. In this paper, we present a review of the application of off-axis electron holography to the quantitative measurement of electrostatic potentials and charge density distributions. We begin with a short overview of the theoretical and experimental basis of the technique. Practical aspects of phase imaging, sample preparation and microscope operation are outlined briefly. Applications of off-axis electron holography to a wide range of materials are then described in more detail. Finally, challenges and future opportunities for electron holography investigations of electrostatic fields and charge density distributions are presented.
Collapse
Affiliation(s)
| | - Rafal E Dunin-Borkowski
- Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons and Peter Grünberg Institute, Forschungszentrum Jülich, 52425 Jülich, Germany
| | - David J Smith
- Department of Physics, Arizona State University, Tempe, AZ 85287, USA
| |
Collapse
|
7
|
Towards quantitative electrostatic potential mapping of working semiconductor devices using off-axis electron holography. Ultramicroscopy 2015; 152:10-20. [DOI: 10.1016/j.ultramic.2014.12.012] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2014] [Revised: 11/05/2014] [Accepted: 12/29/2014] [Indexed: 11/17/2022]
|
8
|
|
9
|
Somodi P, Twitchett-Harrison A, Midgley P, Kardynał B, Barnes C, Dunin-Borkowski R. Finite element simulations of electrostatic dopant potentials in thin semiconductor specimens for electron holography. Ultramicroscopy 2013; 134:160-6. [DOI: 10.1016/j.ultramic.2013.06.023] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2013] [Revised: 06/29/2013] [Accepted: 06/29/2013] [Indexed: 11/28/2022]
|
10
|
Cooper D, Dunin-Borkowski RE. Interpretation of phase images of delta-doped layers. Microscopy (Oxf) 2013; 62 Suppl 1:S87-98. [DOI: 10.1093/jmicro/dft014] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
|
11
|
McCartney MR, Agarwal N, Chung S, Cullen DA, Han MG, He K, Li L, Wang H, Zhou L, Smith DJ. Quantitative phase imaging of nanoscale electrostatic and magnetic fields using off-axis electron holography. Ultramicroscopy 2010. [DOI: 10.1016/j.ultramic.2010.01.001] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
|
12
|
Midgley PA, Dunin-Borkowski RE. Electron tomography and holography in materials science. NATURE MATERIALS 2009; 8:271-80. [PMID: 19308086 DOI: 10.1038/nmat2406] [Citation(s) in RCA: 393] [Impact Index Per Article: 26.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
The rapid development of electron tomography, in particular the introduction of novel tomographic imaging modes, has led to the visualization and analysis of three-dimensional structural and chemical information from materials at the nanometre level. In addition, the phase information revealed in electron holograms allows electrostatic and magnetic potentials to be mapped quantitatively with high spatial resolution and, when combined with tomography, in three dimensions. Here we present an overview of the techniques of electron tomography and electron holography and demonstrate their capabilities with the aid of case studies that span materials science and the interface between the physical sciences and the life sciences.
Collapse
Affiliation(s)
- Paul A Midgley
- Department of Materials Science & Metallurgy, University of Cambridge, Pembroke Street, Cambridge CB2 3QZ, UK.
| | | |
Collapse
|
13
|
Twitchett-Harrison AC, Yates TJV, Dunin-Borkowski RE, Midgley PA. Quantitative electron holographic tomography for the 3D characterisation of semiconductor device structures. Ultramicroscopy 2008; 108:1401-7. [PMID: 18703284 DOI: 10.1016/j.ultramic.2008.05.014] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2007] [Accepted: 05/19/2008] [Indexed: 11/30/2022]
Abstract
Electron tomography and electron holography experiments have been combined to investigate the 3D electrostatic potential distribution in semiconductor devices. The experimental procedure for the acquisition and data reconstruction of holographic tilt series of silicon p-n junction specimens is described. A quantitative analysis of the experimental results from specimens of two different thicknesses is presented, revealing the 3D electrostatic potential variations arising from the presence of surfaces and damage generated by focused ion beam (FIB) sample preparation. Close to bulk-like properties are measured in the centre of the tomographic reconstruction of the specimen, revealing higher electrically active dopant concentrations compared to the measurements obtained at the specimen surfaces. A comparison of the experimental results from the different thickness specimens has revealed a 'critical' thickness for this specimen preparation method of 350nm that is required for this device structure to retain 'bulk'-like properties in the centre of the membrane.
Collapse
Affiliation(s)
- Alison C Twitchett-Harrison
- Department of Materials Science and Metallurgy, University of Cambridge, Pembroke Street, Cambridge, CB2 3QZ, UK.
| | | | | | | |
Collapse
|
14
|
Dunin–Borkowski R, Kasama T, Harrison R. Electron Holography of Nanostructured Materials. NANOCHARACTERISATION 2007. [DOI: 10.1039/9781847557926-00138] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- R.E. Dunin–Borkowski
- Department of Materials Science and Metallurgy, University of Cambridge Pembroke Street Cambridge CB2 3QZ UK
- Center for Electron Nanoscopy, Technical University of Denmark DK-2800 Kongens Lyngby Denmark
| | - T. Kasama
- Frontier Research System The Institute of Physical and Chemical Research Hatoyama Saitama 350–0395 Japan
- Department of Materials Science and Metallurgy, University of Cambridge Pembroke Street Cambridge CB2 3QZ UK
| | - R.J. Harrison
- Department of Earth Sciences, University of Cambridge Downing Street Cambridge CB2 3EQ UK
| |
Collapse
|
15
|
Twitchett AC, Yates TJV, Dunin-Borkowski RE, Newcomb SB, Midgley PA. Three-dimensional electrostatic potential of a Sip-njunction revealed using tomographic electron holography. ACTA ACUST UNITED AC 2006. [DOI: 10.1088/1742-6596/26/1/007] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
|