Atomic Imaging of Irradiation Damage in Novel 2D Materials and Graphene Heterostructure Devices
We have recently shown that it is possible to engineer the first artificial 2D crystals atom-by-atom by sequential layering of mechanically exfoliated 2D materials on a substrate . We were able to reveal the perfect crystal stacking using a focused ion beam (FIB) scanning electron microscope (SEM) to lift out the heterostructure device region of interest and prepare an ultra-thin cross section suitable for atomic resolution transmission electron microscope (TEM) imaging and elemental analysis. Imaging of the individual graphene layers at the atomic scale has revealed the first correlation between graphene’s atomic layer tortuosity (roughness) and its electrical mobility within graphene-based field effect transistor (FET) devices . The aim of this project is to apply this new cross sectional imaging approach to understand the electrical performance characteristics of a new generation of more sophisticated devices containing exotic 2D materials (MoS2, WS2, phosphorene etc.). The range of 2D crystals is expanding all the time and this has generated the potential for new devices with designer bandstructures: synthesized by the stacking of 2D crystals at the atomic scale [3,4,5]. However, application of these exciting devices is being held back by a poor understanding of irradiation damage in such complex structures. The image shows the changes to graphene structure produced by heavy ion irradiation damage.
In this project you will be one of only a few PhD students able to use the University of Manchester’s £3 million Titan ChemiSTEM atomic resolution scanning transmission electron microscope (STEM). You will explore the structure of layered 2D device heterostructures in their pristine state, after device failure and as a function of irradiation damage. This will be used to generate a better understanding of structure-property relationships and to optimize device performance. You will also learn other advanced characterization techniques (FIB, SEM etc), image analysis and device construction. Depending on the interest of the student, there will be opportunities for investigating the device failure modes in situ within the Titan microscope using our unique suite of new electrical characterisation and environmental cell systems to investigate the influence of different atmospheric conditions.
Applicants should have or expect to achieve at least a 2.1 honours degree in Physics, Material Science, Chemistry, Engineering or similar.
Funding covers tuition fees and annual maintenance payments of at least the Research Council minimum (currently £13,863) for eligible UK and EU applicants. EU nationals must have lived in the UK for 3 years prior to the start of the programme to be eligible for a full award (fees and stipend).