Nanoscale device engineering and plasmon-enhanced light-matter interactions for optically accessible resistive switches
Lead Research Organisation:
University of Cambridge
Department Name: Physics
Abstract
The project intends to reveal the exact switching mechanism in the RRAMs of various architectures. Using the process recently achieved by the Di Martino Lab [8], we develop innovative fast ways to study real-time movement of individual atoms in the filament formation process. Understanding the nanoscale kinetics of the switching mechanisms should reveal means for the controlled and effective device optimization. An ultimate goal of the project is to develop a RRAM device with high endurance and low programming energy. This would allow for the practical applications of memristive computing, opening up new routes to sustainable future IT.
The project involves a combination of physical experiments, equipment modification, optical and electrical characterization, numerical simulation, and analytical description. Memristive devices are tested optically while being slowly switched from OFF to the ON state (and back). The optical response provides data for the modelling of the exact atom movement.
So far, the nanoscale kinetics of RRAMs has been explicitly modelled based on the dark field spectroscopy data [8]. In this project we would like to extend the methodology to Raman spectroscopy. So far, we are involved in testing of the RRAMs based on NiO, hBN, and HfO2 which are provided by the Department of Engineering and Material Science of the Cambridge University. In the future, we plan to be pursue various new materials with the potential to become effective memristive switches.
The project involves a combination of physical experiments, equipment modification, optical and electrical characterization, numerical simulation, and analytical description. Memristive devices are tested optically while being slowly switched from OFF to the ON state (and back). The optical response provides data for the modelling of the exact atom movement.
So far, the nanoscale kinetics of RRAMs has been explicitly modelled based on the dark field spectroscopy data [8]. In this project we would like to extend the methodology to Raman spectroscopy. So far, we are involved in testing of the RRAMs based on NiO, hBN, and HfO2 which are provided by the Department of Engineering and Material Science of the Cambridge University. In the future, we plan to be pursue various new materials with the potential to become effective memristive switches.
Studentship Projects
| Project Reference | Relationship | Related To | Start | End | Student Name |
|---|---|---|---|---|---|
| EP/N509620/1 | 01/10/2016 | 30/09/2022 | |||
| 2274778 | Studentship | EP/N509620/1 | 01/10/2019 | 31/03/2023 | Joanna Symonowicz |
| EP/R513180/1 | 01/10/2018 | 30/09/2023 | |||
| 2274778 | Studentship | EP/R513180/1 | 01/10/2019 | 31/03/2023 | Joanna Symonowicz |
| Description | Memristors are one of the most promising contenders for an ultralow-energy computing. In regular transistor-based computers a memory and CPU units are separate. Accordingly, sending signals between the two consumes up to 80% of the input energy. Unlike in standard transistors, a logical (ON/OFF) state in memristors is saved even when voltage is no longer supplied. Accordingly, there is no need for sending signals between two separate logic and memory units, reducing energy consumption significantly. Moreover, data is saved even when we forget to click the 'save' button. Unfortunately, currently a poor understanding of the switching mechanisms in memristors is preventing their commercial utilization. In my first two years of PhD I managed to build a scientific setup for testing memristive switches, which is based on the analysis of their spectral response. The method is non-invasive and in-operando. Currently I am testing memristors based on 2D materials, such as h-BN and MoS2. |
| Exploitation Route | I am open to test memristive materials from any group which would like to understand the nano-scale kinetics of their switching mechanism. |
| Sectors | Digital/Communication/Information Technologies (including Software),Electronics,Energy,Environment |
| Title | Research Data supporting "Fully optical in operando investigation of ambient condition electrical switching in MoS2 nanodevices" |
| Description | The research project the data originated from: MoS2 nanoswitches have shown superb ultra-low switching energies without excessive leakage currents. However, the debate about the origin and volatility of electrical switching is unresolved due to the lack of adequate nano-imaging of devices in operando. Here, we combine three optical techniques to perform the first non-invasive in situ characterization of nanosized MoS2 devices. Our study reveals volatile threshold resistive switching due to the intercalation of metallic atoms from electrodes directly between Mo and S atoms, without the assistance of sulfur vacancies. We observe a 'semi-memristive' effect driven by an organic adlayer adjacent to MoS2, which suggests that non-volatility can be achieved by careful interface engineering. Our findings provide a crucial understanding of nano-process in vertically biased MoS2 nanosheets, which opens new routes to conscious engineering and optimization of 2D electronics. $$ \ $$ The dataset usage instructions: Names of data files correspond to the names of Figures whose data they contain. Files: Figure_1f.002 and Figure_S3a.013_2 are rough AFM scans used for Figures 1f and S3a, respectively. To process the data, please download the Gwyddion software and follow the instructions from: http://gwyddion.net/. Optical and electrical data for Figures 1b-c, 2-3, 4a, 4d, 5a, S2a-b, S5 can be processed using any software for data analysis, such as Spyder (https://www.spyder-ide.org/). All optical data was pre-processed with background subtraction. Additionally, dark field scattering data (Fig. 1b, 4a, 4d, S2b) were reference normalized. Lorentzian curves were fitted to data (Fig. 1c, 2c, 3c) using Spyder software. Finally, Lorentzian fits of the photoluminescence response were subtracted to achieve clear Raman spectra (Fig. 1c, 3c insert). For all electrical data current was recalculated to current density by dividing measured current by electrode's area (706.5 nm2). The outcome of FDTD simulations was exported to .txt format and provided in files for Figures 4b-c, S2c, and S4. It can be accessed by any software for data analysis, such as Spyder (https://www.spyder-ide.org/). $$ \ $$ The data collection methods: The optical and electrical data (files for Figures 1b-c, 2-3, 4a, 4d, 5a, S2a-b, S5) were collected using self-made setup as described in: https://doi.org/10.1002/adma.202209968, 5 Experimental Section -> Electrical Setup, Optical Setup. The setup was operated with self-written software in Python 3. FDTD simulations (files for Figures 4b-c, S2c, and S4) were performed as described in https://doi.org/10.1002/adma.202209968, 5 Experimental Section -> Electrical Setup, FDTD Simulations. Atomic force microscopy (AFM) scans (files for Figures 1f and S3) were collected with the AFM Multimode Nanoscope III. All data were collected at the University of Cambridge, Department of Materials Science & Metallurgy. |
| Type Of Material | Database/Collection of data |
| Year Produced | 2023 |
| Provided To Others? | Yes |
| Impact | This is data for the scientific paper in https://onlinelibrary.wiley.com/doi/full/10.1002/adma.202209968. These findings provide a crucial understanding of nanoprocess in vertically biased MoS2 nanosheets, which opens new routes to conscious engineering and optimization of 2D electronics. |
| URL | https://www.repository.cam.ac.uk/handle/1810/345398 |
| Description | Providing MoS2 and h-BN as a memristive switching material for testing |
| Organisation | Vienna University of Technology |
| Country | Austria |
| Sector | Academic/University |
| PI Contribution | I am testing MoS2 and h-BN memristive cells provided by TU Wien (Thomas Mueller's group) in order to assess its suitability for being a memristive switch. |
| Collaborator Contribution | Dr Dmitry Polushkin from TU Wien has grown MoS2 materials for me. Moreover, he manufactured Au/h-BN/Au memristive structures which I will test next. |
| Impact | This collaboration resulted in a scientific paper in Advanced Materials (impact factor 32): https://onlinelibrary.wiley.com/doi/full/10.1002/adma.202209968 |
| Start Year | 2021 |
| Description | Providing h-BN as a memristive switching material for testing |
| Organisation | University of Cambridge |
| Department | Department of Engineering |
| Country | United Kingdom |
| Sector | Academic/University |
| PI Contribution | I am testing the suitability of h-BN grown by prof. Hoffman's group for being a memristive switch. |
| Collaborator Contribution | Prof. Hoffman's group has grown h-BN for my tests. |
| Impact | My only outcome are preliminary results. |
| Start Year | 2019 |