2D nanocrystal heterostructures - novel production methods and device applications
Lead Research Organisation:
University of Exeter
Department Name: Engineering Computer Science and Maths
Abstract
Strain-engineering is an emerging field in graphene research that exploits the unique physical properties of this two-dimensional honeycomb structure of carbon atoms, in particular its amenability to external influences, including mechanical deformation. An intriguing recent prediction is that distortion of the graphene lattice creates large pseudo-magnetic fields, which can be controlled with appropriately applied-strain geometry. Furthermore, charge carriers in different valleys of graphene's bandstructure will experience different pseudo-magnetic fields, such that strain might be used to control future graphene devices, opening up the whole new field of 'valleytronics', in a similar fashion to how electron spin is used in spintronics or quantum computing.
This project will investigate the effect of strain on the Raman spectra from graphene suspended just above an electrostatic gate. We will thus be able to finely control and tune the amount of strain in these graphene nanoresonator devices, whilst simultaneously studying the Raman signatures of both the in-plane and out-of-plane graphene deformation.
Such non-uniform straining of the suspended graphene membrane is expected to result the graphene exhibiting homogeneous gauge fields which act in a similar way to magnetic fields, thereby inducing Landau levels in the absence of any external magnetic fields. During the project we will develop ways to detect the presence of such pseudo-magnetic fields.
This project will investigate the effect of strain on the Raman spectra from graphene suspended just above an electrostatic gate. We will thus be able to finely control and tune the amount of strain in these graphene nanoresonator devices, whilst simultaneously studying the Raman signatures of both the in-plane and out-of-plane graphene deformation.
Such non-uniform straining of the suspended graphene membrane is expected to result the graphene exhibiting homogeneous gauge fields which act in a similar way to magnetic fields, thereby inducing Landau levels in the absence of any external magnetic fields. During the project we will develop ways to detect the presence of such pseudo-magnetic fields.
Organisations
Studentship Projects
| Project Reference | Relationship | Related To | Start | End | Student Name |
|---|---|---|---|---|---|
| EP/N509656/1 | 01/10/2016 | 30/09/2021 | |||
| 1918745 | Studentship | EP/N509656/1 | 01/10/2017 | 30/09/2022 | Darren Nutting |
| EP/R513210/1 | 01/10/2018 | 30/09/2023 | |||
| 1918745 | Studentship | EP/R513210/1 | 01/10/2017 | 30/09/2022 | Darren Nutting |
| Description | Firstly it should be noted that I had to transfer projects to a new supervisor, so although my award focuses on strain engineering and psuedomagnetic fields, the project I am working on now focuses on heterostructures made from transition metal dichalcogenides (TMDCs) and their properties. In addition I have also done significant work on scalable heterostructures made from abraded films, along with collaborating on a number of other projects. A key finding with the abraded heterostructures was that they can be used to produce scalable, efficient heterostructure devices which out perform the current best method (liquid phase exfoliation) of producing these. To demonstrate this I made a number of devices such as photodetectors, strain sensors, thermostats, pressure sensors and triboelectric nanogenerators. I have been characterising a number of TMDC field effect transistors in the hope of finding an optimal dielectric to improve device performance, with the eventual goal to continue Moore's Law as silicon-based transistors are reaching their fundamental scaling limits. All of the above devices performed orders of magnitude better than comparable devices within the literature. This new abrasive deposition technology allows for the formation of nanocrystalline films and heterostructures of arbitrary size and complexity, as well as being extremely high quality. All of which are requirements for uptake in the next generation of transparent and flexible electronics. |
| Exploitation Route | It is too early to say for certain but I believe that the scalable abraded heterostructures could be used to produce next generation triboelectric nanogenerators which could be used (in series with a capacitor) to produce portable recharging packs for phones, or to provide electricity to household devices. This is based off the high performance of my initial devices, so I am hopeful that with enough optimisation they could provide a practical route for small scale renewable energy. |
| Sectors | Electronics,Energy,Manufacturing, including Industrial Biotechology |
| URL | https://www.nature.com/articles/s41467-020-16717-4 |