Graphene-coated copper electrodes could replace gold in biosensors, cutting signal losses and improving sensitivity. Graphene’s exceptional properties have been difficult to exploit in practical devices because manufacturing methods lack the control needed for consistent, high-quality results. The interface between graphene and the metal it grows on—typically copper—is poorly understood, leading to defects and variable performance. This project tackles that bottleneck by building a vacuum system that deposits graphene and metal layers one after another without ever exposing the sample to air. That atomic-scale control over interfaces, borrowed from semiconductor manufacturing, should produce cleaner, more reproducible graphene-metal structures. If the approach works, it could transform sensor manufacturing. Biosensors that currently rely on gold electrodes could switch to graphene-coated copper, which conducts radiofrequency and microwave signals with lower losses. The same process could also produce free-standing graphene membranes and tiny mechanical beams, enabling arrays of nanomechanical sensors for detecting cells or biomolecules. Beyond sensors, these structures would let researchers explore graphene’s unusual optical properties—confined plasmon-polariton excitations—that are now a hot topic in fundamental science. The project is primarily about solving a manufacturing problem, but that solution could unlock both practical devices and deeper understanding of graphene physics.
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In spite of its challenging properties, the utilization of graphene for technical applications still demands considerable efforts in developing dedicated processing methods, which have a potential to be adapted and finally utilized for industrial scale device manufacturing. Among the processes which have been investigated so far, chemical vapour deposition of graphene on copper, where copper acts as a catalyst to facilitate the growth of single layered graphene - appears to be one the most promising approaches. Although extensively studied, there are issues with this process related to quality, reproducibility and yield, which are connected to the lack of control of the interface between copper and graphene. Within the process, which we will be able to tackle these issues in a more controllable way by a combined in-situ deposition system, where copper and other possible metals are deposited within one vacuum system together with the graphene CVD, i.e without exposing the sample to an ambient environment. Like for 2D Ga-Al-As semiconductor heterostructures, the control of the interfaces on an atomic length scale by means of an in-situ multilayer deposition process is expected to be the pathway which will enable the ultilization of graphene's unqiue properties within manufacturable device structures. In spite of this potential, we feel the full integration of graphene into CMOS technology, although being extremely challenging on the long term - still has a very long way to go and may even be impossible without fundamentally different processing approaches. However, sensor technologies as a whole are mostly based on hybrid solutions, where the sensor itself - even chip based in some cases - is still separated from the CMOS digital electronic by flip chip, wire bonding or simple by conventional wiring. A widely used example of high indutrial impact are piezoelectric sensors, where the high processing temperature of the lead-zirconium-titanate ceramics are incompatible with CMOS processing conditions. Based on this philosophy, we believe that the in-situ growing approach for metal-graphene multilayers, as envisaged to be developed within this project, will enable a significant improvement of existing sensor concepts and the realization and manufacturing of new sensor concepts. Based on the expertise of our scientific partners within Imperial College and NPL and our associated partners from industry, we will focus on biosensor applications, where graphene - as carbon based material - is particularly challenging as bio-interface. As - from the point of view of process technology -the most simple approach, graphene coated copper electrodes will have a potential for radiofrequency - microwave - terahertz biosensor, where copper will outperform gold due to lower conduction losses and graphene provides the interface to the biomolecules and cells. As a second step on a scale of increasing complexity of process technology, we believe that a sacrificial layer process for arbitrary shaped free standing graphene membranes and (sub)micro scale flexural beam is a realistic development goal. This technology will enable the development of arrays of nanomechanical sensors, based on the exceptional mechanical properties of graphene. Apart from sensor applications, graphene- based NEMS structures are challenging objects for the refinement and exploration of metrology for nanotechnology and biology, as being pursued by our collaborators from NPL. The recently discovered confined plasmon-polariton excitations - originating from the unique electronic properties of graphene - are currently one of the hottest topic within the graphene research community. We believe, that the tailored free standing structures we will be able to manufacture with this deposition kit, will pave the way to explore and finally utilize this unique optical - infrared properties of graphene for novel sensor applications.
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