Facilities and equipment
The National Graphene Institute (NGI) has pioneering laboratory space which enables collaborative research between academia and industry.
Our laboratory spaces offer flexible workspace for companies to collaborate with our academics. We operate as part of a "hub and spoke" model with other institutions which enables interdisciplinary research in physics, material science, electronic and electrical engineering among many others.
With our partners, we work on a diverse range of projects from new concepts and applications of graphene to designing the most efficient manufacturing methods. We also take a look at graphene standardisation and quality control, and health and safety in its manufacture and use.
The National Graphene Institute has 7,825 square metres of laboratory space. This is divided up into 20 research laboratories which are a mix of general facilities, specific research areas and spaces for our industrial collaborators. We also have two wet chemistry labs with 10 fume cupboards and requisite equipment for the preparation and modification of graphene and other 2D materials.
Our dedicated lab spaces are listed below.
The characterisation facility consists of a range of modern instruments dedicated to the characterisation of novel 2D materials.
Techniques include atomic force microscopy for force measurements and imaging. AFM-IR combining atomic force microscopy and infrared spectrophotometry, scanning electrochemical microscopy used to measure the local electrochemical behaviour of liquid/solid, liquid/gas and liquid/liquid interfaces, thermal diffusivity, drop shape analyser for the measurement of surface wetting and adhesion and physical adsorption of gas molecules on a solid surface.
Located across two laboratories and totalling more than 120m2 we have wet chemistry facilities for the handling, preparation and modification of 2D materials.
The furnace lab is equipped with a suite of furnaces dedicated to large area chemical vapour deposition of 2D materials and the surface treatment of substrates.
A prototyping lab equipped with 5 axis CNC, indexed lathe, 3D printer and associated equipment to support the fabrication of devices and services to the cleanrooms and laboratories. It also has two large open laboratories designed to be flexible and change with research demand.
The raman suite provides multiply laser systems for chemical and structural characterisation, which are suitable for investigation of samples in both solid and liquid states.
The research facilities currently located within the National Graphene Institute are: energy, membranes and nano fluidics, composites, digital fabrication and optical (cryostat, laser spectroscopy etc).
The NGI houses 1,500 square metres of ISO class 5 and 6 cleanrooms over two floors.
Detailed information about our facilities is listed below.
We provide the capability to firstly clean substrate/sacrificial wafers with our solvent wetdecks and fumehoods, complete with sonic baths and waste disposal drip-cups connected to a semi-automated carboy system.
Next, we have the facilities to allow users to spincoat and bake a variety of polymer layers onto their substrates for the purposes of flake preparation/transfer or lithography (optical or e-beam). The suite of Nikon microscopes allows the location and identification of flakes.
Finally, our bespoke flake transfer rigs can be used to position and transfer 2D flakes onto substrates or onto other flakes to allow the building of 2D heterostructures.
The cleanroom facility has extensive ‘thin film’ characterisation tools: high resolution SEM, HRFIB, modelling ellipsometry, raman, large area atomic force microscopy, UHV scanning probe microscopy, optical spectroscopy and profile with stress measurement.
Deposition is one of the main steps in standard microfabrication processes. It involves depositing a thin layer of material on a substrate, typically nanometers and up to a few micrometers.
The source material is usually a gas, a vapour or simply atoms or molecules ejected from a solid material. It is often performed at low pressures or in vacuum (ranging from just a few hundred pascals below atmospheric pressure to ultra-high vacuum) in order to minimise impurities and in many cases as a strict requirement for process viability (eg so that ejected particles from the source will reach the substrate).
The two main deposition methods employed in semiconductor processing are Chemical Vapour Deposition (CVD) and Physical Vapour Deposition.
The Focused Ion Beam Scanning Electron Microscope is one of the most versatile pieces of equipment in this cleanroom. It is a high specification dual-beam instrument used to fabricate, measure and characterise nano-devices.
The ion beam can etch structures in graphene or other materials, or be used to deposit conducting or insulating material in a precise manner. The high-resolution electron column can then be used to accurately image the device.
This is a highly controlled area of the cleanroom services with its own air supply and temperature controlled to within 0.1 degrees.
To achieve the largest 2D flakes through mechanical exfoliation onto a solid substrate such as SiO2, the surface of the substrate must be totally free of organic contaminants, this will maximise the strength of the interaction between the flakes and the substrates.
Low power plasma etching can be used as a final step in the cleaning of Si/SiO2 substrates before deposition of 2D flakes to promote adhesion, removing residual organic contaminants left over from chemical cleaning; it can also be used for the surface cleaning of other, more exotic substrates such as PDMS; finally it can be used for the highly controlled etching of graphene mono- and multi-layers.
The photolithography process draws similarities with the processes associated with photography. In both processes, an image or pattern is transferred onto a substrate by exposing a thin film of material to radiation in the visible to ultra-violet range.
The regions exposed to radiation undergo a chemical reaction, which is subsequently enhanced and further processed by the application of heat and the interaction with other chemicals.
The pattern on this thin film of photoresist is thus "developed", which in lithography involves leaving a pattern of resist on the substrate, which may represent the direct image of the intended structure or its negative image.
In our cleanrooms, many aspects of graphene and 2D materials research are made possible by processes borrowed from thin-film or semiconductor processing.
Many of these processes are well established having been developed and fine-tuned over many decades of research and industrial activities. Others need to be adapted to the specific requirements of 2D materials research.
In particular, the term "wet chemistry" encompasses a large variety of processes based on liquid chemicals commonly used in semiconductor processing: from substrate cleaning and preparation to etching structures and dissolving resists for metal lift-off.
These processes are performed at a controlled temperature in either purpose-built fume hoods or wet benches using high purity solvents, acids and alkalis.