This project contains the LaTeX files, python scripts and other documents relating course 34029: Physics Project.
This paper analyses simulated vibrational modes in nanomembranes with diameters between 1 and 5 nm, using Atomistix Toolkit, with the purpose of characterising the frequency response of the membrane, along with atomic behaviour of a few localised modes as to obtain a correlation with findings of similar computational simulations of microscale membranes. The nanomembranes in question are both a theoretical single layer idealised membrane and a more realistic double layered membrane, imitating a graphene layer upon a substrate. We hypothesised that the findings of such similar simulations will correlate in behaviour when moving to the nanoscale. As it turns out, the modes do scale, as the membrane sizes reduce to the nanoscale, and the frequencies and atomic movement are easily obtained using our developed analysis tools. Our findings motivates experimental tests on the nanoscale. Such membranes could be setup using nanomesh substrates with a graphene layer attached. These membranes could be produced using block copolymer lithography for the substrate and CVD for the graphene layer.
Since the isolation and characterisation of Graphene in 2004 by Andre Geim and Konstantin Novoselov, scientists have marvelled over the physical properties and potential application of Graphene. Being a relatively new material, many aspects and ideas are being investigated and researched at all times. Graphene yield extreme tensile strength as well as extreme electric conductivity, yet its structure is fairly simple. Graphene consists solely of carbon atoms thus making it easy to simulate using specialised software, since carbon atoms are greatly understood in terms of chemical bonding. As graphene is a very versatile material the possibilities for research in simulation environments are virtually limitless. Therefore it is basically possible to make experiments limited only by imagination, in order to discover new properties and possible applications of graphene. This saves resources before entering the lab, where the simulated reality is tested.
In this rapport we will simulate and analyse the phonons of nanomembranes. In the article "Visualizing the Motion of Graphene Nanodrums", nanomembranes on a microscale are simulated and experimentally tested. The article describes how phonons travel through these membranes. The results of the work in the forementioned article and many others suggests that the simulated phonon models holds true for systems on the micrometer scale when tested in the lab. We will examine if the same phenomenons are found at the nano-scale. To do this we start by considering a ideal system of just one sheet of carbon atoms. By simulating this ideal system in a virtual environment we will analyse the vibrational modes, and frequencies in said modes. By simulating various sizes of membranes, we will examine how scaleable our analysis turns out to be. We will employ the software Atomistic ToolKit (ATK) to carry out these simulations. The software will enable prompt setup of relevant structures with variying parameters. Afterwards in order to make a more realistic scenario we will investigate whether you can create the same membrane effects if you take a graphene layer and put it on top of a substrate with different sized holes, a nanomesh, to form a two layer membrane. It is expected possible to create such a nanomesh at the size of few tens of nanometers at DTU Nanotech with Block-copolymer lithography or TEM structuring of a substrate. We will simulate and analyse these two layer membranes and then compare them to the idealised membranes.
Does drum modes exist in graphene supported by a nanomesh with nanometer sized holes?
- Frederik Grunnet Kristensen: s164003@student.dtu.dk
- Christoffer Vendelbo Sørensen: s163965@student.dtu.dk
- Rasmus Kronborg Finnemann Wiuff: s163977@student.dtu.dk