GB2539016A

GB2539016A - Novel process

Info

Publication number: GB2539016A
Application number: GB1509646.4A
Authority: GB
Inventors: Caffio Marco; Marquordt Claus; Holm Arvidsen John; Anders Brix Haupt Remus
Original assignee: Individual
Current assignee: Individual
Priority date: 2015-06-03
Filing date: 2015-06-03
Publication date: 2016-12-07
Anticipated expiration: 2035-06-03
Also published as: GB201509646D0; GB2539016B

Abstract

Graphene is produced by laser treatment of an amorphous carbon layer or layers which have been previously deposited on a substrate by plasma-enhanced CVD. The plasma deposition process comprises (i) plasma CVD of one or more carbon-containing layers from a carbon source onto a Si-containing substrate, wherein the layer(s) comprise an amorphous nanocarbon film, and (ii) laser treatment of the layered substrate from (i) using a laser to convert the amorphous nanocarbon film to one or more layers of graphene. The temperature at each stage does not exceed the melting temperature of the substrate, and is preferably below 400ºC. In one aspect, a thin film comprising one or more silicon based graphene-philic layers are deposited onto a substrate by PECVD before step (i). This enables a non-silicon containing substrate to be coated with graphene. The graphene-philic Si-based layer may comprise an inorganic material such as a silane or siloxane, or an organic material such as trimethylsilane, tetramethylsilane or tetramethyldisiloxane. In a further aspect, the substrate itself contains Si. The plasma deposition process may comprise magneto luminous chemical vapour deposition (MLCVD). The process is particularly useful since it can be carried out at low temperatures, including room temperature, so that substrates with lower melting temperatures, such as plastics, may be coated.

Description

NOVEL PROCESS

FIELD OF THE INVENTION

The present invention relates to a novel process for graphene deposition at low temperatures, uses of materials produced by said process, and apparatus for use in said process. In particular the invention relates to a process for direct deposition of graphene onto a substrate via deposition of a thin film comprising one or more carbon layers onto a substrate, with subsequent laser treatment to provide one or more layers of graphene, wherein the temperature of each stage is controllable, and optionally wherein an intermediate thin film comprising one or more silicon based graphene-philic layers is deposited onto non-silicon containing substrates.

BACKGROUND

The global graphene market continues to grow year on year and is estimated to reach around $149 million by 2020. This increase is likely to be from demand for higher quantities existing graphene materials to service existing markets and applications, as well as adoption of these and new graphene materials into further applications. In particular the demand for monolayer and bi-layer graphene are anticipated to increase from use of these materials in higher applications, such as consumer electronics, as well as into high performance wearable materials having increased strength and flexibility.

It is generally accepted that the current methods for producing graphene films, such as micromechanical cleavage, sublimation of silicon from SiC in ultra-high vacuum, and chemical vapour deposition (CVD) growth on metal foils, liquid exfoliation of graphite and graphite oxidation to graphene oxide followed by reduction, are useful for the manufacture of films for single flake studies and also for the preparation of relatively large area continuous films.

The graphene films produced via the methods of the art vary in quality and quantity depending upon the methods used. Independent of the method used, there are difficulties associated with scale-up.

To date there is no scalable production method for making graphene films in sufficient quantities at within a suitable time-frame to be suitable for use in in-line processing.

To date there is no scalable production methods for making graphene films of suitable quality for use in in-line processes.

Thus there is a need for a manufacturing method for production of graphene films which is suitable for use in in-line processing and which provides graphene films of sufficient quality and quantity for commercial purposes.

In addition, the Applicant has considered that as ever-new applications for graphene films are created, there will also be a need for manufacturing processes which are capable of providing such films onto a wider-range of substrate materials than is presently possible, and in particular material s which presently provide challenges, such as flexible plastic materials with temperature challenges, and silicon wafers for which there is not plasma-based process for graphene deposition to date.

To service these new markets there is an urgent need for a scalable production method for depositing graphene films onto challenging substrates including flexible plastic materials and silicon wafers.

Thus there is a need for a process which is capable of providing one or more graphene layers onto substrate materials at lower temperatures than is possible with processes of the art.

Thus there is a need for a process which is capable of providing one or more graphene layers onto plastics, silicon wafers and other materials which are not presently compatible with the processes of the art.

Thus there is a need for an improved process suitable for provision of one or more graphene layers onto a substrate material which is: suitable for use in continuous processing; is high-speed; is reproducible; is capable at operating across a range of temperatures, and in particular at low temperatures; and is suitable for use across a range of substrates, and in particular with plastic substrates.

It is an object of the invention to provide and improved plasma-based process suitable for the provision of one or more graphene layers onto a substrate material and capable of stand-alone use as a batch process, as well as utility in in-line processing, wherein the improved plasma-based process which overcomes the issues of slow-speed and lack of reproducibility, and the incompatibility issues for in-line processing associated with the current plasma-based processes of the art for graphene deposition.

It is an object of the invention to provide an improved plasma-enhanced chemical vapour deposition (PECVD) process suitable for the provision of one or more graphene layers onto a substrate material using a plasma-based process which overcomes the incompatibility issues for in-line processing associated with the plasma-based techniques of the art.

It is an object of the invention to provide an improved catalyst-free plasma-enhanced chemical vapour deposition (PECVD) process suitable for the provision of one or more graphene layers onto a substrate material using a plasma-based process which is operable at low temperatures.

It is an object of the invention to provide an improved plasma-enhanced chemical vapour deposition (PECVD) process suitable for the provision of one or more graphene layers onto a substrate material which overcomes the issues of slow-speed and lack of reproducibility of the current processes for graphene deposition.

It is an object of the invention to provide an improved plasma-enhanced chemical vapour deposition (PECVD) process suitable for the provision of one or more graphene layers onto a substrate material which is reproducible and capable of providing graphene of desired quantity and quality.

It is an object of the invention to provide an improved plasma-enhanced chemical vapour deposition (PECVD) process for the provision of one or more graphene layers onto a substrate material at high-speed and which is suitable for use with a range of substrate materials, including flexible plastics, silicon, and wafers of silicon and/or silicon oxide.

It is an object of the invention to provide an improved plasma-enhanced chemical vapour deposition (PECVD) process for the provision of one or more graphene layers onto a substrate material at high-speed and at an overall process temperature which is less than 450°C and in particular is operational at temperatures in the range of from room temperature to about 120°C, and which is suitable for use with a range of substrate materials, including flexible plastics, silicon, and wafers of silicon and/or silicon oxide.

The Applicant has now developed a novel and inventive process for the provision of one or more graphene layers onto a substrate surface.

SUMMARY OF THE INVENTION

The present invention relates to a novel process for graphene deposition at low temperatures, to uses of materials produced by said process, and to apparatus for use in said process. In particular the invention relates to a 3-stage process for direct deposition of one or more graphene layers onto a non-silicon containing substrate via deposition of a thin film comprising one or more silicon based graphene-philic layers onto a substrate, provision of one or more carbon layers thereon, with subsequent laser treatment to provide one or more graphene layers and wherein the temperature of each stage is controllable.

The invention additionally relates to a 2-stage process for direct deposition of graphene onto a silicon containing substrate via deposition of a thin film comprising one or more carbon layers onto the substrate, with subsequent laser treatment to provide one or more layers of graphene, wherein the temperature of each stage is controllable.

According to a first aspect the invention provides a plasma-based 3-stage process for direct deposition of one or more graphene layers onto a substrate at low temperature comprising: (a) Plasma deposition of a thin film comprising one or more silicon based graphene-philic layers onto a substrate via plasma enhanced chemical vapour deposition (PECVD); (b) Plasma deposition of the layered substrate from (a) with a carbon source to provide one or more carbon-containing layers on the substrate via plasma enhanced chemical vapour deposition (PECVD) wherein the further layer is an amorphous nanocarbon film; and (c) Laser treatment of the layered substrate from (b) using a laser to convert the amorphous nanocarbon film to one or more graphene layers wherein the temperature at each stage does not exceed the melting temperature of the substrate.

According to a yet further aspect the invention provides a plasma-based 3-stage process for direct deposition of one or more graphene layers onto a non-silicon containing substrate at low temperature comprising: (a) Plasma deposition of a thin film comprising one or more silicon based graphene-philic layers onto a substrate via magneto luminous chemical vapour treatment (MLCVD), (b) MLCVD plasma-deposition of the layered substrate with a carbon source to provide one or more carbon-containing layers on the substrate wherein the further layer is an amorphous nanocarbon film; (c) Laser treatment of the layered substrate from (b) using a laser to convert the amorphous nanocarbon film to one or more graphene layers and wherein the temperature at each stage does not exceed the melting temperature of the substrate.

According to a still further aspect the invention provides a plasma-based process in accordance with any of the aspects of the 3-stage processes indicated hereinbefore wherein the one or more silicon based graphene-philic layers is an inorganic SiOx layer or and organo-silicon layer, and particularly an SiC,, or SiCMCI to at)alkyl layer wherein x, y and (C1 to C4)alkyl are as defined hereinafter.

According to another aspect the invention provides a 2-stage plasma-based process for direct deposition of one or more graphene layers onto a silicon containing substrate at low temperature comprising: (i) Plasma deposition of the substrate with a carbon source to provide a thin film comprising one or more carbon-containing layers onto the substrate wherein the further layer is an amorphous nanocarbon film via plasma enhanced chemical vapour deposition (PECVD); and (ii) Laser treatment of the layered substrate from (i) using a laser to convert the amorphous nanocarbon film to one or more graphene layers wherein the temperature at each stage does not exceed the melting temperature of the substrate.

According to another aspect the invention provides a plasma-based process for direct deposition of one or more graphene layers onto a silicon containing substrate at low temperature comprising: (i) Plasma deposition of the substrate with a carbon source to provide a thin film comprising one or more carbon-containing layers onto the substrate wherein the further layer is an amorphous nanocarbon film via magneto luminous chemical vapour treatment (MLCVD); and (ii) Laser treatment of the layered substrate from (i) using a laser to convert the amorphous nanocarbon film to one or more graphene layers wherein the temperature at each stage does not exceed the melting temperature of the substrate.

The above and further aspects of the invention are described hereinafter.

DESCRIPTION OF THE INVENTION DEFINITIONS

A low temperature process as defined herein means a process wherein the temperature, at each stage of the process does not exceed the melting point of the substrate. According to an aspect the present invention provides a process as defined hereinbefore wherein the temperature is less than 450°C. For the avoidance of doubt, a temperature of less than 450°C as defined herein means that the maximum temperature at any stage of the process remains under 450°C. In particular a low temperature process as defined herein is a process wherein the operating temperatures throughout the process are within the ranges independently selected from: from -100°C to about 400°C; from 0°C; to about 400°C; from room temperature to about 400°C; from room temperature to about 350°C; room temperature to about 300°C; from room temperature to about 120°C; from room temperature to 99°C; from about 50°C to about 99°C; from about 30°C to about 40°C. Room temperature as defined herein is about 25°C. The Applicant has found that the present process can be carried out in the absence of a dedicated heat source, and that the heat generated by the plasma is sufficient for the depositions in steps (a) and (b), and the heat generated by the laser is sufficient for the conversion in step (c).

Thus there is provided a process as defined herein before wherein the temperature is from RT to about 99°C, from RT to about 50°C, from about 30°C to about 40°C.

This is surprising because prior to the present process, it had been well-understood that high temperatures, in excess of 450°C, in combination with one or more suitable catalysts were required for graphene deposition, optionally in combination with high pressure conditions. Suitable substrate materials for use herein are detailed hereinafter.

A fast process as defined herein means a high-speed process wherein a layer of graphene is deposited onto a substrate within a matter of minutes, and depending upon the selected graphene source, substrate, process temperature, MLCVD and laser settings, can take as little as a few seconds.

MLCVD

Magneto luminous chemical vapour deposition (MLCVD), also known as magneto luminous plasma polymerisation is a term of the art, given to a plasma polymerisation technique in which radicals, ionized molecules and atoms are localised to produce plasma using a magnetic structure in order to deposit materials onto substrates.

According to an aspect in the present process MLCVD is utilised both in an initial, or first stage, for the deposition of a thin film comprising one or more silicon based graphene-philic layers onto a substrate, and also, in a further, or second stage, for the deposition of an amorphous carbon nanofilm onto the so-formed one or more silicon based graphene-philic layers on the substrate.

According to another aspect in the present process the substrate is a silicon-based material independently selected from: silicon or wafers of silicon and/or silicon oxide, and MLCVD is utilised for the direct deposition of a thin film comprising an amorphous carbon nanofilm onto the substrate followed by laser treatment to convert the nanofilm into one or more graphene layers as detailed he rein before.

Thus, there is provided a plasma-based 2-stage process for direct deposition of one or more graphene layers onto a silicon-based substrate at low temperature comprising: (i) MLCVD plasma-deposition of the layered substrate with a carbon source to provide one or more carbon-containing layers on the substrate wherein the further layer is an amorphous nanocarbon film; and (ii) Laser treatment of the layered substrate from (i) using a laser to convert the amorphous nanocarbon film to one or more graphene layers wherein the temperature at each stage does not exceed the melting temperature of the substrate. DISCUSSION OF THE PROCESS OF THE INVENTION The Applicant has developed a novel and improved process for high-speed, direct deposition of one or more layers of graphene onto desired substrates across a range of temperatures, and in particular for use at low temperatures.

Advantageously the process of the present invention facilitates the production of one or more layers of graphene at a low temperature onto challenging substrate materials which hitherto had not been practicably possible, such as for example flexible plastics, silicon, and wafers of silicon and/or silicon oxide.

As the process of the present invention provides direct deposition of one or more graphene layers onto an intermediate layer of the substrate the overall process is faster than previous processes because there is no classic "transfer" stage.

Furthermore because the present process does not require the use of a catalyst, such as a metal film as utilised in processes of the art, the directly deposited graphene layer(s) provided by the present process has reduced potential for impurities and/or defects.

As the present process is a fast process this means that for the first time it is possible to provide an in-line process for deposition of one or more graphene layers onto a substrate within an in-line manufacturing process.

Substrate A substrate material as defined herein is the material onto which the one or more desired graphene layers is/are to be formed in due course. For the avoidance of doubt, the substrate can comprise a moulded part, a part-mould, a complete mould, an entire device, a component for a device, a wafer and the like.

Any suitable substrate material may be utilised in the present process. A challenging substrate material, as defined herein includes substrates having a lower melting point than can be processed using current techniques, and in particular a melting point of: less than 450°C; less than 350°C; less than 250°C; less than 150°C; less than 120°C; between room temperature and about 120°C, as well as substrate materials which are difficult to handle in current techniques such as for example silicon wafers. Suitable substrate materials for use in the present process include, but are not restricted to: flexible plastic materials; clear plastic materials; transparent plastic materials; silicon; a wafer of silicon and/or silicon oxide ceramics; glass; textiles; and the like. For the avoidance of doubt a silicon wafer is a wafer suitable for use in the electronics or photovoltaic fields, suitable silicon wafers typically have thicknesses of 160pm to 300pm, and for electronic applications are usually circular with diameters of from 25.4mm to 300mm, and for photovoltaic applications are typically square and from 100mm2 to 300mm2. Thus, according to a further aspect the present invention provides a process as detailed hereinbefore wherein the substrate is independently selected from: plastic materials; flexible plastic materials; clear plastic materials; thermoplastic polymeric materials; transparent plastic materials; silicon; a wafer of silicon and/or silicon oxide; ceramic materials; glass; textiles; wafers.

Exemplary substrate materials suitable for use in the present process include: polystyrene (PS); silicon; a wafer of silicon and/or silicon oxide; polyethylene terephthalate also known as polyethylene terephthalate); (PET) or (PETE); polypropylene (PP); cyclic olefin copolymer also known as ethylene copolymer (000); poly(methylmethacrylate) (PMMA); polydimethylsiloxane (PDMS); polycarbonate (PC); ',thermoplastic elastomers (TPE5), such as styrenic block copolymers (TPE-s,l, polyolefin blends (TPE-o), elastorneric alloys (TPE-v or TM!), thermoplastic polyurethanes (TPUs); thermoplastic copolyester, or thermoplastic polyamides (COP); poly-lactic co-glycolic acid (PGLA); polylactic acid also known as polylactide (PLA); and acrylonitrile butadiene styrene (ABS).

According to a yet further aspect the present invention provides a process as detailed hereinbefore wherein the substrate is independently selected from: a flexible plastic material; a clear plastic material; a transparent plastic material; silicon; a wafer of silicon and/or silicon oxide; a ceramic material; glass; a textile; a wafer and the temperature is: less than about 450°C; from -100°C to about 400°C; from 0°C to about 400°C; from room temperature (RD to about 400°C; from RT to about 350°C; from RT to about 300°C; from RT to about 120°C; from RT to 99°C; from about 50°C to about 99°C; from about 30°C to about 40°C.

According to a yet further aspect the present invention provides a 3-stage process as detailed hereinbefore wherein the substrate is polystyrene and the temperature is: from RT to about to about 120°C; from RT to 99°C; from about 50°C to about 99°C; from about 30°C to about 40°C.

According to a yet further aspect the present invention provides a 2-stage process as detailed hereinbefore wherein the substrate is a silicon containing material independently selected from: silicon; a silicon wafer; a silicon oxide wafer; a silicon/silicon oxide wafer and the temperature is: from RT to about 120°C; from RT to 99°C; from about 50°C to about 99°C; from about 30°C to about 40°C.

Surprisingly the Applicant has found that use of the present process enables the production of one or more graphene layers onto desired substrates using a low temperature plasma-based process operable at room temperature.

Graphene-philic layer As detailed hereinbefore where the substrate is a non-silicon containing substrate the process is a 3-stage process wherein one or more graphene-philic layers are deposited onto the substrate prior to deposition of one or more carton-containing layers with subsequent laser treatment to provide the desired one or more layers of graphene on the substrate.

A graphene-philic layer as defined herein is a thin film comprising one or more silicon based graphene-philic layers of material which is/are deposited onto the substrate during stage 1 / step (a) of the present process via plasma polymerisation using MLCVD.

Any silicon containing material capable of utility within a PECVD process to deposit a silicon based graphene-philic layer is suitable for use herein. Both inorganic and organic silicon containing materials can be used with the PECVD process in the present process.

Suitable inorganic silicon containing materials for use herein include: silicon-based monomeric materials; linear and cyclic siloxanes; silanes; parental silicon-based materials.

Exemplary inorganic silicon containing materials for use herein are silane (SiH4), and/or disilane (Si2H6). For the avoidance of doubt any suitable commercially available silane or disilane can be utilised in the present process.

Suitable organic silicon containing materials, also called organo-silicon materials, for use herein include: silicon-based monomeric materials; linear and cyclic siloxanes; parental silicon-based materials.

Organo-silicon materials preferred for use herein are materials which when subjected to plasma-based deposition in accordance with the present process furnish one or more silicon based graphene- philic layers wherein the one or more layers are independently selected from: SiOx, SiCy, or SiOx(Ci-C4)alkyl layer wherein x and y have values from 1 to 4.

Exemplary organic silicon containing materials for use herein are: trimethylsilane (SiC3H8); tetramethylsilane (S i (C H3)4); methoxymethyltrimethylsilane(CH3OCH2Si(CH3)3); 1,1,3,3-tetramethyldisiloxane ([(CH3)2Sil-]20). For the avoidance of doubt any suitable commercially available source of the exemplary organic silicon containing materials can be utilised in the present process.

Thus according to another aspect the present invention provides a process as defined herein wherein the thin film comprises one or more silicon based graphene-philic layers is an SiOx, SiCy, or SiOx(Ci-C4)alkyl layer wherein x and y are values: between 1 and 4; between 1 and 2. For the avoidance of doubt x and y can independently of one another be any number within the defined ranges as well as the start or end values of the ranges hereinbefore i.e. 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0. Where x and/or y has a non-stoichiometric value, the silicon based graphene-philic layer is an amorphous film. According to a further aspect the present invention provides a process as defined herein wherein the thin film comprises one or more layers of SiOx or SiCy.

The Applicant has found that particular silicon-based materials are especially useful for the provision of the desired one or more graphene-philic layers. Without wishing to be bound to any particular theory it is proposed herein that use of these materials facilitates enhanced decoupling of graphene from the mount part (in due course), to furnish graphene with substantially unchanged electronic properties.

It is also proposed herein that Si atoms are involved in the graphene formation process via a dissolution / segregation mechanism in Stage 3 / Step (c).

This Stage can be generally considered to be use of a PECVD process, and in particular of MLCVD to induce the deposition of a thin film comprising one or more silicon-based graphene-philic layers onto a substrate within a reaction chamber, wherein the chamber contains silicon-based monomers and oxygen which react when the plasma is generated by the PECVD process, and in particular by MLCVD to produce the graphene-philic material is deposited onto the substrate in due course. In one embodiment this can be represented as application of MLCVD to substrate + monomeric Si-based material + 02.

The term, thin film when used in relation to the one or more silicon based graphene-philic layers herein, is defined herein as a film of thickness in the range of from about 10 to about 1000nm.

The Applicant has found that a thin film comprising one or more silicon based graphene-philic layers of from about 10 to about 1000nm, and from about 40 to about 60nm, in thickness can be deposited onto substrate materials using the present process. Thus according to a further aspect the present invention provides a process as defined herein wherein the thin film comprising one or more silicon based graphene-philic layers has a thickness of from: 10 to about 1000nm, from about 20 to about 1000nm, from about 20 to about 500nm, from about 30 to about 100nm, from about 40 to about 60nm.

According to another aspect the present invention provides a process as defined herein wherein the thin film comprising one or more silicon based graphene-philic layers is a film comprising one or more Si0", SiCy, or SiOy(CI-C4)alkyl layers wherein x and y have values between 1 and 4 as defined herein before and wherein the thin film has a thickness of from 10 to 1000nm.

The Applicant has developed a suitable reaction chamber in which the present process for treatment of suitable substrates can be carried out. An illustration of this chamber is provided in Figure 1 and is discussed in detail hereinafter. The advantage of using such a single chamber-based system is that the risk of contamination during transfer of the treated surface between stages is mitigated / obviated, and also the speed at which the entire process can be carried out is enhanced. In addition, the utility of a single-contained reaction chamber in which to deposit one or more graphene layers onto a desired substrate enables, for the first time, graphene deposition as one or more layers as part of an in-line manufacturing process.

Conditions for generation of graphene-philic layer In Stage 1, also called step (a), the desired substrate material is transferred into the reaction chamber, and held in place via suitable fixing means. Suitable fixing means as defined herein is any means capable of holding the substrate in place throughout the multi-step process, and in particular is a holder adapted to accept and retain one or more substrates, such as for example the spinning or rotating wheel illustrated in Figure 1. The spinning or rotating wheel can accommodate from 1 to 20 substrates which can be the same or different, depending upon the relative dimensions, thicknesses, of the substrates. The dimensions of each substrate holder on the wheel are designed to accommodate substrates of up to 100mm maximal length in any direction. For the avoidance of doubt the thickness of the substrates can vary, in other words the wheel can accommodate different substrates, provided they comply with the length restriction. The relative thickness of each substrate is from 160pm up to about 2mm and a mixture of different substrates having different dimensions can be used. The chamber is then evacuated and a silicon-based monomeric material and, or a silicon-based monomeric material and oxygen are introduced in gaseous form, via any suitable means, such as for example pumping, metering valve or mass flow controller. If oxygen is introduced first, a suitable source material for the to-be-deposited thin film comprising one or more silicon based graphene-philic layers can then be provided into the chamber in gaseous form, and if the suitable source material is introduced first in gaseous form, the oxygen can then be provided, and alternatively both gaseous materials can be introduced at the same time.

According to a further aspect there is provided a process as defined herein wherein the process is carried out in a reaction chamber wherein the desired substrate material is transferred into the reaction chamber, and held in place via suitable fixing means and wherein the chamber is then evacuated and a silicon-based monomeric material and, or a silicon-based monomeric material and oxygen are introduced in gaseous form, via any suitable means.

According to another aspect there is provided a process as defined herein wherein the process is carried out in a reaction chamber wherein the desired substrate material is transferred into the reaction chamber, and held in place via suitable fixing means and wherein oxygen is then introduced into the reaction chamber and then a suitable source material for the to-be-deposited thin film comprising one or more silicon based graphene-philic layers is provided into the chamber in gaseous form, or wherein the suitable source material is introduced to the chamber in gaseous form, and the oxygen can then be provided, or both gaseous materials, the a suitable source material for the to-be-deposited thin film comprising one or more silicon based graphene-philic layers and oxygen can be introduced at the same time.

The Applicant has found that low pressure conditions are advantageous for the provision of desirable silicon based thin layers onto substrate materials in Stage 1. Low pressure as defined herein means a pressure in the range independently selected from: from about 10-2 mbar up to and including about 10-1 mbar; from about 5 x 10-2 mbar up to and including about 10-1 mbar; from about 2 x 10-2 mbar up to and including about 10-1 mbar.

The Applicant has found that carefully controlled plasma polymerisation conditions are valuable for the provision of desirable wettability i.e. the provision of the thin film comprising one or more silicon based graphene-philic layers which completely covers, or substantially covers the surface of the substrate which is to be coated. In particular the Applicant has found that gas flow rates for the oxygen and source material are independently selected from: from about 1 standard cubic centimetre per minute (sccm) to about 1 Osccm; from about lsccm to about 5sccm; from about 1.5sccm to about 4sccm are useful. Similarly the Applicant has found that glow discharge parameters in the ranges independently selected from: from about 5 watts to about 100watts; from about 10 watts to about 90watts; from about 20watts to about 80watts can be used.

The Applicant has additionally found that the graphene-philic layer can be deposited within a short time frame, and within from 10 seconds to 10 minutes, from within 30 seconds to 5 minutes, from within 1 to 5 minutes, from within 2 to 5 minutes.

According to a further aspect the present invention provides a process as defined hereinbefore wherein in step (a) the conditions are independently selected from: a temperature of from room temperature to less than 450°C or about 120°C; a pressure of from about 10-2 mbar up to and including about 10.1 mbar; wherein the gas flow rate for the oxygen is from about lsccm to about l0sccm; wherein the gas flow rate for the silicon-based material is from about lsccm to about 10sccm; wherein the glow discharge parameters are from about 5 watts to about 100watts, and wherein the PECVD/MLCVD is carried out from 10 seconds to 10 minutes.

According to a further aspect the present invention provides a process as defined hereinbefore wherein in step (a) the conditions are: a temperature of from room temperature to less than 450°C or about 120°C; a pressure of from about 10-2 mbar up to and including about 10-1 mbar; a gas flow rate for the oxygen of from about 1sccm to about l Osccm; a gas flow rate for the silicon-based material of from about lsccm to about 10sccm; and glow discharge parameters of from about 5 watts to about 100watts.

According to a further aspect the present invention provides a process as defined hereinbefore wherein in step (a) the conditions are: a temperature of from about 50°C to about 99°C or from 30°C to about 40°C; a pressure of from about 10-2 mbarup to and including about 10-1 mbar; a gas flow rate for the oxygen of from about lsccm to about l Osccm; a gas flow rate for the silicon-based material of from about lsccm to about l0sccm; and glow discharge parameters of from about 5watts to about 100watts.

Carbon Source Any suitable carbon source can be utilised in Stage 2 / step (b) in order to generate one or more carbon-containing layers onto the thin film comprising one or more silicon based graphene-philic layers as generated in Stage 1 / step (a), or in order to generate one or more carbon-containing layers directly onto the substrate in step (i) as detailed herein. Suitable carbon sources include: methane (CH4); ethylene (C2H4); ethane (02H6); carbon monoxide (CO); carbon dioxide (002); 2,2-dimethylpropane (05H12); propadiene (C31-14);1,2-butadiene (04H6);1,3-butadiene (041-16);2-methylproPane (C41-110); cyclopropane (C3H6); propene C31-16); toluene (C71-18); benzene (C6I-16)-A carbon-containing layer as defined herein is a layer of material which is deposited onto the thin film comprising one or more silicon based graphene-philic layers of the coated substrate during stage 2 / step (b), or onto the substrate in step (i) via plasma polymerisation treatment with a suitable PECVD process, and in particular with MLCVD. The Applicant has found that particular carbon sources are especially useful for the provision of carbon-containing layers. Without wishing to be bound to any particular theory it is proposed herein that use of these materials in Stage 2/step (b) or step (i)/ is valuable for the provision of one or more carbon-containing layers with reduced defects and longer grain sizes than is possible using conventional plasma, or laser-based transformational processes.

The term, thin film when used in relation to the one or more carbon-containing layers herein, is defined herein as a film of thickness in the range independently selected from: from about 10 to about 1000nm; from about 20 to about 1000nm, from about 20 to about 500nm, from about 30 to about 100nm, from about 40 to about 60nm.

Stage 2, step (b) can be generally considered to be the application of a suitable PECVD process, and in particular MLCVD to a substrate coated with a thin film comprising one or more silicon based graphene-philic layers, within a reaction chamber wherein a suitable source of carbon is present. In one embodiment this can be represented as application of PECVD or MLCVD to Si0"-coated substrate + H2 + carbon source.

Step (i) can be generally considered to be the application of a suitable PECVD process, and in particular MLCVD to a silicon containing substrate, within a reaction chamber wherein a suitable source of carbon is present. In one embodiment this can be represented as application of PECVD or MLCVD to Si-containing + H2 + carbon source.

Conditions for generation of carbon-containing layer In Stage 2, the substrate material, now coated with a thin film comprising one or more silicon based graphene-philic layers remains within the reaction chamber, the chamber is evacuated again, and the new process gases are pumped in. In one embodiment H2 and a gaseous carbon source are introduced into the chamber.

According to a further aspect there is provided a process as defined herein wherein stage 2 of the process is carried out in the same reaction chamber as stage 1, wherein the substrate material now coated with a thin film comprising one or more silicon based graphene-philic layers remains within the reaction chamber, and remains held in place via suitable fixing means and wherein the chamber is evacuated and a gaseous carbon source and hydrogen are introduced in gaseous form, via any

suitable means.

According to another aspect there is provided a process as defined herein wherein stage 2 of the process is carried out in the same reaction chamber as stage 1, as detailed hereinbefore and wherein hydrogen is then introduced into the reaction chamber and then a gaseous carbon source, or wherein the gaseous carbon source and hydrogen are introduced at the same time.

The Applicant has found that low pressure conditions are advantageous for the provision of desirable carbon-containing layers onto the coated substrates in Stage 2. Low pressure as defined herein means a pressure in the range of from about 10-2 mbar up to and including 10-1 mbar. As indicated hereinbefore, in Stage 2, for the first time the present process provides means for the deposition of a precursor layer for the production of one or more layers of graphene under room temperature conditions. Advantageously as no catalyst is utilised in Stage 2, or in step (i) and the controlled deposition is provided by a fast process, and the resultant deposited one or more carbon-containing layer has a high density of free radicals and/or dangling bonds.

The Applicant has found that carefully controlled plasma polymerisation conditions are valuable for the provision of one or more carbon-containing layers having desirable properties. According to a further aspect the present invention provides a process as defined hereinbefore wherein the process conditions are as detailed hereinafter.

For the avoidance of doubt the conditions detailed herein for Stage 2, step (b) apply equally to step (ii) where the process is carried out on a silicon containing substrate.

The Applicant has additionally found that the carbon containing layer can be deposited within a short time frame, and within from 10 seconds to 10 minutes, from within 30 seconds to 5 minutes, from within 1 to 5 minutes, from within 2 to 5 minutes.

According to a further aspect the present invention provides a process as defined hereinbefore wherein in step (b) or in step (ii) the conditions are independently selected from: a temperature of from room temperature to less than 450°C or about 120°C; a pressure of from about 10-2 mbar up to and including about 10-1 mbar; wherein the gas flow rate for the hydrogen is from about lsccm to about lOsccm; wherein the gas flow rate for the carbon source is from about lsccm to about lOsccm; wherein the glow discharge parameters are from about 5watts to about 100watts, and wherein the PECVD / MLCVD is carried out from about 1 to about 5 minutes.

According to a further aspect the present invention provides a process as defined hereinbefore wherein in step (b) or in step (ii) the conditions are: a temperature of from room temperature to less than 450°C or about 120°C; a pressure of from about 10-2 mbar up to and including about 10-1 mbar; a gas flow rate for the hydrogen of from about lsccm to about lOsccm; a gas flow rate for the carbon source of from about Isom to about 1 Osccm; and glow discharge parameters of from about 5watts to about 100watts.

According to a further aspect the present invention provides a process as defined hereinbefore wherein in step (b) or in step (ii) the conditions are: a temperature of from about 50°C to about 99°C or from 30°C to about 40°C; a pressure of from about 10-2 mbar up to and including about 10-1 mbar; a gas flow rate for the hydrogen of from about lsccm to about lOsccm; a gas flow rate for the carbon source of from about Isom to about 1 Osccm; and glow discharge parameters of from about 5watts to about 100watts.

Graphene The present process is directed to the provision of one or more graphene layers, also called layers of graphene, on a desired substrate. Graphene is an allotrope of carbon, and is a well-known term of the art, and in general terms is one of a group of low-dimensional carbon nano-materials which also includes other carbon allotropes, carbon nanotubes and fullerene. Graphene is the basic structural element from which these further carbon allotropes are formed. A graphene layer is a 2-dimensional monolayer of sp2 carbon atoms arranged in a hexagonal shape, within a honeycomb lattice structure.

In particular, Stage 3 / step (c), or step (ii), of the present process provides for the deposition of one or more graphene layers onto a desired substrate. Thus, according to a further aspect the present invention provides a process for the provision of one or more graphene layers onto a desired substrate wherein each of one or more layers is a 2-dimensional monolayer of sp2 carbon atoms arranged in a hexagonal shape, within a honeycomb lattice structure.

According to a yet further aspect the present invention provides a process for the provision of a 2-dimensional monolayer of graphene as defined herein.

S According to a further aspect the present invention provides a process for the provision of a 3-dimensional, or stacked-structure of up to 10 layers, preferably from 1 to 6, more preferably 1 to 3 layers of sp2 carbon atoms arranged in a hexagonal lattice shape wherein each layer comprises a 2-dimensional monolayer, and the layers are stacked one on top of the other.

Where the present process provides a graphene-containing thin film comprising from 3 to 10 layers of graphene onto the desired substrate such layers are also known as carbon nanowalls (CNNs), nanostructure graphite, or few layer graphene sheets (FLGS).

For the avoidance of doubt, whilst the skilled person will appreciate that there are multiple applications for thin substrate materials onto which one or more graphene layer is deposited in accordance with the present process, the present process is not necessarily limited to the deposition of one or more layers of graphene onto a thin film or wafer of substrate material.

The one or more graphene layers are provided on the substrate via transformation of an amorphous carbon nanofilm into one or more layers of graphene via pulsed or continuous laser irradiation using a laser as discussed hereinafter and as indicated by Stage 3 / step (c) or in step (i).

Any suitable carbon source can be used for the generation of an amorphous carbon nanofilm, also known as a C-film on a desired substrate material via PECVD polymerisation, and in particular using MLCVD, in Stage 2 / step (b), or in step (i), as described hereinbefore.

As detailed hereinbefore an amorphous carbon nanofilm as defined herein is a thin film. The amorphous carbon nanofilm has a thickness of from about 10 to about 1000nm, from about 20 to about 1000nm, from about 20 to about 500nm, from about 30 to about 100nm, from about 40 to about 60nm. The term amorphous in relation to the carbon nanofilm as defined herein means a film without regular or definable structure alternatively it can be called a non-crystalline film. As also detailed hereinbefore suitable carbon sources for the generation of an amorphous carbon nanofilm include: methane (CH4), ethylene (C2H4), ethane (C2H6), carbon monoxide (CO), carbon dioxide (CO2).

A carbon-containing layer as defined herein is a layer of material which is deposited onto the thin film comprising one or more silicon based graphene-philic layers of the coated substrate during Stage 2 / step (b), or directly onto a silicon-containing substrate in step (i), via plasma polymerisation treatment with MLCVD. The Applicant has found that particular carbon sources are especially useful for the provision of carbon-containing layers having a high density of free radicals or dangling bonds.

Without wishing to be bound to any particular theory it is proposed herein that use of these materials in step (b), or step (i), is valuable for the provision of one or more graphene layers (in Stage 3/ step (c) or in step (ii)) wherein the so-produced one or more graphene layers has reduced defects and longer grain sizes than is possible using conventional plasma, or laser-based transformational processes.

Stage 2, step (b) can be generally considered to be the application of MLCVD to a substrate coated with a thin film comprising one or more silicon based graphene-philic layers, within a reaction chamber where a carbon source and hydrogen are present. In one embodiment this can be represented as application of MLCVD to Si-film coated-substrate + carbon source + H2.

In Stage 2, the silicon-coated substrate is in the reaction chamber, held in place via suitable fixing means. The chamber is evacuated, to remove reaction gases from stage 1, and a suitable carbon source and hydrogen are then introduced into the so-evacuated chamber in gaseous form, via any suitable means, such as for example pumping, metering valve or mass flow controller. If hydrogen is introduced first, a suitable source material for the to-be-deposited thin film comprising one or more layers of carbon containing material can then be provided into the chamber in gaseous form, and if the suitable carbon source material is introduced first in gaseous form, the hydrogen can then be provided, and alternatively both gaseous materials can be introduced at the same time.

Step (i) can be generally considered to be the application of MLCVD to a silicon containing substrate, within a reaction chamber where a carbon source and hydrogen are present. In one embodiment this can be represented as application of MLCVD to Si-containing-substrate + carbon source + H2.

According to a further aspect the present invention provides a process as defined hereinbefore wherein in step (b) the conditions are independently selected from: a temperature of from room temperature to less than 450°C; a pressure of from about 10-2 mbar up to and including about 10-1 mbar; wherein the gas flow rate for the hydrogen is from about 1sccm to about 10sccm; wherein the gas flow rate for the carbon source is from about 1sccm to about lOsccm; wherein the glow discharge parameters are from about 20watts to about 100watts.

According to a further aspect the present invention provides a process as defined hereinbefore wherein in step (b) the conditions are: a temperature of from room temperature to less than 450°C; a pressure of from about 10-2 mbar up to and including about 10-1 mbar; a gas flow rate for the hydrogen of from about 1sccm to about 10sccm; a gas flow rate for the carbon source of from about lsccm to about 1 Osccm; and glow discharge parameters of from about 20watts to about 100watts.

According to a further aspect the present invention provides a process as defined hereinbefore wherein in step (b) the conditions are: a temperature of from about 50°C to about 99°C; a pressure of from about 10-2 mbar up to and including about 10-1 mbar; a gas flow rate for the hydrogen of from about lsccm to about 10sccm; a gas flow rate for the carbon source of from about lsccm to about 10sccm; and glow discharge parameters of from about 20watts to about 100watts.

Conditions for laser treatment In the final step of the process herein the coated substrate, from Stage 2, step (b), or from step (i) remains within the reaction chamber, the reaction chamber is evacuated again, and then a suitable laser, such as a visible or UV-laser as detailed hereinafter, is applied to the carbon-containing layer.

Thus, according to a further aspect there is provided a process as defined herein wherein Stage 3 of the process is carried out in the same reaction chamber as used for Stages 1 and 2, and wherein the substrate material now coated with a first thin film comprising one or more silicon based graphenephilic layers and a further thin film of one or more layers of a carbon-containing material remains within the reaction chamber, and remains held in place via suitable fixing means, and wherein the chamber is evacuated and a laser is applied to the carbon-containing layer.

According to a yet further aspect there is provided a process as defined herein wherein step (ii) of the process is carried out in the same reaction chamber as used for step (i), and wherein the silicon-containing substrate material now coated with a thin film of one or more layers of a carbon-containing material remains within the reaction chamber, and remains held in place via suitable fixing means, and wherein the chamber is evacuated and a laser is applied to the carbon-containing layer.

The Applicant has found that control of the laser conditions is advantageous for the deposition of one or more layers of graphene onto the surface of the coated substrate. The laser frequency and power levels can be controlled. Suitable wavelengths for use in the present process are in the range of from about 1080nm to about 248nm; from about 532nm to about 248nm. Suitable power levels are in the range of from about 1 to 5 Watts. Whilst higher power levels can be used, for optimal results levels within the range of from 1 to 5 Watts are preferred. The Applicant has additionally found that the laser treatment can be effectively carried out within a short time frame, and within from 10 seconds to 10 minutes, from within 30 seconds to 5 minutes, from within 1 to 5 minutes, from within 2 to 5 minutes.

Thus, according to a further aspect the present invention provides a process as defined hereinbefore wherein, in steps (c) or (ii), the laser conditions are: a wavelength in the range of from about 1080nm to about 248nm; a power level in the range of from about 1 to 5 Watts and wherein the laser treatment is carried out from 10 seconds to 10 minutes.

As indicated hereinbefore, in Stage 3/step (c), or in step (ii), for the first time the present process provides means for the direct deposition of one or more layers of graphene onto a desired substrate surface under low temperature conditions. Advantageously, the Applicant has found that the so-produced one or more graphene layers has comparable defect levels, versus graphene deposited onto substrates using conventional chemical vapour deposition (CVD) processes.

It is particularly surprising that graphene layers comparable to those provided via convention CVD can be provided using the process of the present invention because not only does the present process operate at temperatures far lower than those currently possible, and in particular room temperature, but in addition the present process does not require the use of catalytic materials.

Without wishing to be bound to any particular theory it is proposed herein that the carbon-containing layer is heated and then decomposed, by irradiation of a pulsed or continuous wave laser beam.

For non-silicon containing substrates having a graphene-philic coating, it is proposed that the carbon atoms are dissolved in the thin film comprising one or more silicon-based graphene-philic layers, and then extracted to form graphene when the temperature is decreased. This decomposition-dissolutionsegregation (DDS) enables direct deposition of the one or more graphene layers onto the original substrate.

For silicon containing substrates, it is proposed that the carbon atoms are dissolved in the surface layers of the substrate, and then extracted to form graphene when the temperature is decreased.

This decomposition-dissolution-segregation (DDS) enables direct deposition of the one or more graphene layers onto the original substrate.

According to a further aspect the present invention provides a substrate having one or more layers of graphene deposited thereon wherein the graphene is independently selected from: a graphene monolayer; from 1 to 10 layers of graphene; from 1 to 6 layers of graphene; from 1 to 3 layers of graphene.

It is generally accepted that the relative thickness of a graphene mono-layer can be affected by the substrate material onto which it has been deposited, and that thicknesses in the range of from 0.35nm to about 1 nm are typical.

Thus, according to a further aspect the present invention provides a process for the provision of one or more graphene layers deposited thereon wherein the thickness of each layer is from about 0.35nm to about 1nm. According to a further aspect there is provided a process for the provision of a graphene monolayer having a thickness of from 0.35 to about 1 nm; for the provision of up to 10 layers of graphene at a total thickness of from 3.5 to about lOnm.

For the avoidance of doubt the present invention includes the combination of the conditions indicated herein for Stages 1, 2 and 3 at steps (a), (b) and (c) for non-silicon containing substrates, as well as the combination of the conditions indicated herein for steps (i) and (ii) for silicon-containing substrates, particularly wherein the silicon-containing substrate is silicon, or a silicon and/or silicon oxide wafer.

As indicated hereinbefore, there is an demand for graphene-coated materials suitable for use in a is wide variety of industrial and medical applications within the semi-conductor, electronics, medical technology and/or biotechnological fields including: the provision of barrier properties; the provision of anti-fouling or anti-icing properties; provision of improved mechanical strength to substrate materials such as stronger yarn fibres for wearable or commercial fabrics, provision of scratch-resistant coatings; the provision of electrical conductive properties such as for batteries or fuel cells, for super conductors, touch screens, batteries or fuel cells; provision of transparent and/or flexible electronic materials; and the like.

Thus, according to a further aspect the present invention provides a process as defined hereinbefore for the provision of graphene-coated substrate materials suitable for use in the semi-conductor, electronics, medical technologies and/or biotechnological fields.

According to a further aspect still, the present invention relates to the use of a layered-substrate produced by the process as defined herein: for the production of semi-conductors, or in the production of semi-conductor components; for the production of electrical conductors, or in the production of components for electrical conducting products; and/or for the production of a medical device, or in the production of one or more components for a medical device.

MLCVD

Magneto luminous chemical vapour deposition (MLCVD) is utilised in the present process for plasma polymerisation in Stages 1 and 2 / steps (a) and (b), and in step (i).

In general terms, MLCVD provides a properly shaped and intense magnetic field, capable of trapping electrons in an electric field, and thereby causing them to move in spirals instead of straight lines. This alternative motion increases the frequency of collisions between electrons and gas molecules, which in turn causes more fragmentation, higher deposition rates and homogenous coating depositions at lower pressures.

The magnetic field confines the glow volume in the inter-electrode region, which dramatically reduces the deposition elsewhere in the reactor. The confined glow dramatically reduces the wall contamination and increases the yield of plasma deposition onto substrates to the level of 40%, while the yield of most RF plasma functionalization and polymerization is around 1%. The lower reactor wall contamination reduces the frequency of necessary cleaning of the reactor and makes it possible to operate a continuous operation for a longer period time. lowers the breakdown voltage of molecules dramatically and makes it possible to operate plasma deposition in low-pressure domains with the characteristics of a low voltage / high current process. This yields a uniform deposition of film on the substrate placed in the gas phase according to the rapid step growth plasma deposition and polymerization mechanism.

The dissociation glow shifts from the electrode surface to the gas phase. This shift causes the major deposition to occur on the substrate leaving the electrode surfaces with very little deposition. This makes prolonged operation of the plasma deposition possible. It also decreases the frequency of preventive maintenance breaks. Laser

Any laser capable of affecting the transformation of the amorphous carbon nanofilm into one or more layers of graphene can be used herein. Suitable lasers include visible and UV lasers.

Reaction Chamber The Applicant has developed a reactor, having an internal space known as a reaction chamber, suitable for carrying out the present process. Illustrations of a reaction chamber within such a reactor and aspects thereof are provided in Figures 1 to 6 herein.

The reactor may be manufactured from any suitable material. For the avoidance of doubt a suitable material as defined herein is a material capable of providing a safe internal environment (the reaction chamber) for carrying out the various process steps, and being inert to the conditions therein. Exemplary materials for the manufacture of a reactor include: stainless steel.

Whilst it will be appreciated that the external shape of the reactor, and the internal shape of the reaction chamber can be modified, the internal volume of the reactor, i.e. the volume capacity of the reaction chamber should be sufficient to enable the desired transformations to be carried out.

The reactor illustrated in Figure 1 consists of a stainless steel vacuum chamber of a total volume of around 62 I. The pumping system as illustrated in Figure 1 is composed of a series of pumps which can guarantee a basic vacuum of from 5 to 8x10-4 mbar in a reasonable evacuation time. As also illustrated in Figure 1 the pressure into the reactor is controlled by a butterfly valve mounted between the chamber and the pumping system, which is controlled by a pressure controller.

Advantageously this arrangement enables variation of the pre-set value of the pressure delivered into the reaction chamber at an independently pre-fixed value of flow. This provides a system which decouples the effect of the system pressure from the effect of flow rate.

The gas flow rates are regulated by a mass flow controller mounted on the top of the chamber in order to have a homogenous flow, of from 1 to 20sccm, in the space between the electrodes.

The samples can be fixed onto a rotating or spinning wheel, which is rotating or spinning at speeds of from about 5 to about 20 revolutions per minute (rpm), and which is kept at a floating potential between the two electrodes. The way the substrates are attached depends on the shape of the samples. The substrates rotate in and out from the inter-electrode space to get a better uniformity over the surface. For the avoidance of doubt slower and faster speeds can be used, such as for example speeds in the range of from about 1 to about 25rpm.

The electrodes are made of titanium or aluminium and have a size of 18.5x19x0.15 cm. They are connected to a symmetric 15 kHz power supply of from 50 to 800 volts (V). A circular shaped concentric magnetic structure is placed behind each electrode. Each magnetic yoke is formed by placing 8 AINiCo magnet bars (1x1.2x7.3 cm) in a water-cooled stainless steel block (18.5x18.5x2.7 cm). The south poles of the magnet bars are directed towards the centre of the magnetic structure. The ends of the magnet bars are bridged together with ferromagnetic rings with a high magnetic permeability. This magnet arrangement guarantees a magnetic field of approximately Br = 0.025 T at 11.2 mm above the magnetic structure surface. In other words, the electron mean free path and the cyclotron perimeter are in the same order of magnitude and the electrons are efficiently trapped by the magnetic field.

Advantageously, use of the present magnetron plasma polymerization process powered at 15 kHz provides several benefits, versus the radio frequency (RF) techniques of the art, on the control of the growth rate of the thin films in Stages 1/step (a) and 2/step (b) and in step (i). It is known that the control of the film growth rate in the RF techniques is almost an impossible task due to the long list of parameters to consider (flow rate, gas pressure, power, chamber geometry, etc.).

The 15 kHz discharge can overcome this challenge. The low frequency discharge works like two DC discharges with cathode and anode swapping sides every half-cycle and the process becomes current controlled, so the voltage varies according to the gas conditions. In other words, the minimum breakdown voltage and the maximum deposition rate occur at the same pressure value for a given inter-electrode distance. The maximum growth rate can be determined much faster by means of a breakdown voltage (Paschen) curve measurement. The homogeneity of the deposited polymeric thin silicon based graphene-philic film in Stage 1/step(a) or the carbon-based amorphous film in Stage 2/step(b) or step (i) is not influenced either by the inter-electrode distance or by the flow rate. Homogeneity is lightly dependent on the pressure and strongly dependent on the current. This is because the current directly controls the creation of the polymerisable species.

FIGURES

Representative examples of features of the novel process, as well as use of such a process within a in a continuous manufacturing process are illustrated in and are discussed in relation to the Figures presented hereinafter.

For the avoidance of doubt, whilst these Figures illustrate the utility of the present process for the provision of graphene-coated substrates in accordance with aspects of the invention, the particular features of the process as applied to any particular substrate and as discussed herein after are equally applicable for use with alternative substrates in order to produce coated-substrates suitable for use in other industries, than the medical device field and as discussed hereinbefore.

As such the following provide representative examples of particular embodiments of one or more aspects or features of the process of the present invention and are not intended to be limiting thereon.

DESCRIPTION OF THE FIGURES

Figure 1: is front-side view of a plasma generating chamber (1) in which the present process steps (a), (b) and (c) can be carried out. Illustrated in Figure 1 are: (1) a plasma generation chamber suitable for use for the production of one or more layers of graphene as detailed herein; (2), (3), (4), (5) mass flow control (MFC) which are used to control the flow of process gases; (6), (7), 8) and (9) are entry points for various process gases, for example C2H4, H2, 02, SiC3H7; a cooling system (10) having an embedded magnetic structure and electrodes used to generate and localized plasma in the area between the two electrodes; (11) a spinning wheel used as a holder for sample (substrates); (12) a step motor used to rotate the spinning wheel sample holder (12); a laser system (13) which is suitable for use to convert the carbon-containing layers into one or more layers of graphene in the stage 3; a water cooling down pump system (14) which is used to control the temperature of the magnetic structure; (15) power supply; a gate valve (16) used to isolate the plasma generating chamber (1) when samples (substrates) are being loaded onto wheel (11); a throttle valve (17) used to control the process pressure independently from the gas flow; a pressure controller (18); a pressure gauge (19); a turbo pump (20); a fore pump (21); vacuum control valves (22) used to control the pressure during pumping down process.

Figure 2: is a left-side view of a plasma generating chamber (1) in which present process steps (a), (b) and (c) can be carried out. Illustrated in Figure 2 are: a chamber (1) having a flange (23) used to introduce process gas; a flange (24) used to connect the water cooling down pump system (14) with the cooling water down system (10), systems (10) and (14) are illustrated in Figure 1; a flange (25) used to by-pass the fore pump (21) -not shown illustrated in Figure 1; a flange (26) used to connect the laser for Stage 3 / step (c) to the reaction chamber; a flange (27) used to connect power to the electrodes in cooling system (10) -not shown and as illustrated in Figure 1.

Figure 3: is a right-side view of a plasma generating chamber (1) in which present process steps (a), (b) and (c) can be carried out. Illustrated in Figure 3 are: a chamber (1) having a flange (24) used to connect the water cooling down pump system (14) with the cooling water down system (10); a flange (28) used to connect the pressure gauge (19) to the chamber (1); and door (29).

Figure 4 is a front view of the magnetic structure (10) placed behind each electrode of a plasma generating chamber (1) and as illustrated in Figures 1, 2 and 3. Illustrated in Figure 4 are: eight AINiCo magnetic bars one of which is indicated (30); inner and outer ferromagnetic rings indicated by (31 a) and (31 b) respectively; a water-cooled stainless steel block (32) used to control the temperature of the magnetic structure (10).

The following process example indicates one way in which the present process may be carried out to provide direct deposition of graphene onto a substrate material. As will be readily appreciated, for the alternatives discussed hereinbefore, alternative substrates may be used to provide alternative graphene-coated substrates, and alternative carbon sources may be used for the provision of the initial amorphous carbon nanofilm. The skilled person will also appreciate that alternative silicon based graphene-philic layers may also be deposited in Stage 1 / step (a) of the process.

PROCESS EXAMPLES AND EXPERIMENTAL DATA

In the following illustrative examples, a plasma generation chamber in accordance with Figure 1 as detailed herein, can be advantageously used to provide graphene on different substrates.

Example 1

Stage 1: Materials: substrate polystyrene (PS) part 50mm (length) x 30mm (width) and 1.2mm (thickness), source gases oxygen and tetramethylsilane added together. Conditions: RT; pressure 5 x 10-2 mbar; 02 flow rate 2.5sccm; tetramethylsilane flow rate 2.5sccm; glow discharge parameter of 60watts for 5 minutes. Evacuate system prior to stage 2.

Stage 2: Materials: coated PS substrate from Stage 1, source gases hydrogen and ethylene added together. Conditions: RT; pressure 2 x 10-2 mbar; H2 flow rate 3sccm; ethylene flow rate 2sccm; glow discharge parameter of 20watts for 5 minutes. Evacuate system prior to stage 3.

Stage 3: UV laser with wavelength of 532mm and power level of 3 watts for 1 minute is used to convert the amorphous carbon nanofilm from Stage 2 into graphene.

Example 2

Materials: substrate silicon wafer 50mm (length) x 30mm (width) and 1.2mm (thickness), no source gases required as substrate is graphene-philic. Evacuate system prior to stage (i).

Step (i): Materials: silicon wafer, source gases hydrogen and ethylene added together. Conditions: RT; pressure of 5 x 10-2 mbar; H2 flow rate 3sccm; ethylene flow rate 2sccm; glow discharge parameter of 20watts for 5 minutes. Evacuate system prior to step (ii).

Step (ii): UV laser with wavelength of 532mm and power level of 3watts for 1 minute is used to convert the amorphous carbon nanofilm from step (i) into graphene.

Claims

CLAIMS1. A process for direct deposition of one or more layers of graphene onto a substrate at low temperature comprising: (a) Plasma deposition of a thin film comprising one or more silicon based graphene-philic layers onto a substrate via plasma enhanced chemical vapour deposition (PECVD): (b) Plasma deposition of the layered substrate from (a) with a carbon source to provide one or more carbon-containing layers on the substrate via plasma enhanced chemical vapour deposition (PECVD) wherein the further layer is an amorphous nanocarbon film; and (c) Laser treatment of the layered substrate from (b) using a laser wherein the temperature at each stage does not exceed the melting temperature of the substrate.
2. A process for direct deposition of one or more layers of graphene onto a substrate at low temperature comprising: (a) deposition of one or more silicon based graphene-philic layers onto of a substrate via magneto luminous chemical vapour treatment (MLCVD); (b) MLCVD treatment of the layered substrate with a carbon source to provide a further layer comprising one or more carbon-containing layers on the substrate wherein the further layer is an amorphous nanocarbon film; and (c) laser treatment of the layered substrate from (b) using a laser wherein the temperature at each stage does not exceed the melting temperature of the substrate.
3. A process according to Claim 1 or 2 wherein the temperature at each stage is less than 450°C.
4. A process according to any of the preceding claims wherein the temperature at each stage is independently selected: from -100°C to about 400°C; from 0°C to about 400°C; from room temperature (RT) to about 400°C; from RT to about 350°C; from RT to about 300°C; from RT to about 120°C; from RT to 99°C; from about 50°C to about 99°C; from RT to about 40°C.
5. A process according to any of the preceding claims wherein the graphene-philic layer is a thin film of from lOnm to 1000nm in thickness.
6. A process according to any of the preceding claims wherein the graphene-philic layer is an inorganic silicon containing material independently selected from: silicon-based monomeric materials; linear and cyclic siloxanes; silanes; and parental silicon-based materials.
7. A process according to any of the preceding claims wherein the graphene-philic layer is an inorganic silicon containing material independently selected from silane (SiH4) and disilane (Si2H6).
8. A process according to any of the preceding claims wherein the graphene-philic layer is an organic silicon containing material.
9. A process according to any of the preceding claims wherein the graphene-philic layer is an organic silicon containing material independently selected from: silicon-based monomeric materials; linear and cyclic siloxanes; and parental silicon-based materials.
10. A process according to any of the preceding claims wherein the graphene-philic layer is an organic silicon containing material independently selected from: trimethylsilane (SiC31-18); tetramethylsilane (Si(CH3)4); methoxymethyltrimethylsilane(CH3OCH2Si(CH3)3); 1,1,3,3-tetramethyldisiloxane ([(CH3)2SH]20).
11. A process according to any of the preceding claims wherein the pressure in step (a) is in the range of from about 10-2 mbar to about 10-1 mbar.
12. A process according to any of the preceding claims wherein the wherein the gas flow rates in step (a) for the oxygen and for the gaseous silicon-based material are both from about lsccm to about 10sccm.
13. A process according to any of the preceding claims wherein the glow discharge parameters in step (a) are from about 5watts to about 100watts.
14. A plasma-based process for direct deposition of one or more graphene layers onto a silicon containing substrate at low temperature comprising: (i) Plasma deposition of the substrate with a carbon source to provide a thin film comprising one or more carbon-containing layers onto the substrate wherein the further layer is an amorphous nanocarbon film via plasma enhanced chemical vapour deposition (PECVD); and (ii) Laser treatment of the layered substrate from (i) using a laser to convert the amorphous nanocarbon film to one or more graphene layers wherein the temperature at each stage does not exceed the melting temperature of the substrate.
15. A process according to Claim 14 wherein plasma deposition is carried out via magneto luminous chemical vapour treatment (MLCVD).
16. A process according to any of the preceding claims wherein the carbon source is independently selected from: methane (CH4); ethylene (C2H4); ethane (C2116); carbon monoxide (CO); carbon dioxide (CO2); 2,2-dimethylpropane (C5H12); propadiene (C3H4);1,2-butadiene (C4H6);1,3-butadiene (C4H6);2-methylpropane (C4H10); cyclopropane (C3H6); propene C3H6); toluene (C7H3); benzene (C61-16)- 17. A process according to any of the preceding claims wherein the amorphous nanocarbon film is a thin film of from 10 to 1000nm in thickness.18. A process according to any of the preceding claims wherein the pressure in step (b) or step (i) is in the range of from about 10-2 mbarto about 101 mbar. 45 19. A process according to any of the preceding claims wherein the wherein the gas flow rates in step (b) or step (i) for the hydrogen and for the carbon source gas are both from about lsccm to about 10sccm.20. A process according to any of the preceding claims wherein the glow discharge parameters in step (b) or step (i) are from about 5watts to about 100watts.21. A process according to any of the preceding claims wherein the laser in step (c) or step (ii) is a visible or a UV laser.22. A process according to any of the preceding claims wherein the wavelength of the laser in step (c) or step (ii) is in the range of from about 1080nm to about 248nm.23. A process according to any of the preceding claims wherein the laser in step (c) or step (ii) has a power level in the range of from about 1 to 5 Watts.24. A process according to any of the preceding claims wherein a single layer of graphene is deposited onto the substrate in step (c) or step (ii). 10 25. A process according to any of the preceding claims wherein a 2-dimensional monolayer of graphene is deposited onto the substrate in step (c) or step (ii).26. A process according to any of the preceding claims wherein a 3-dimensional, or stacked-structure of up to 10 layers, or from 1 to 6 layers of graphene is deposited onto the substrate in step (c) or step (ii).27. A process according to any of claims 14 or 15 wherein the silicon containing substrate material is independently selected from: silicon; wafers of silicon and/or silicon oxide; glass.. 20 28 A process according to any of claims 1 to 13 wherein the substrate material is independently selected from non-silicon containing materials independently selected from: plastic materials; flexible plastic materials; clear plastic materials; thermoplastic polymeric materials; transparent plastic materials; ceramic materials; textiles; wafers.29. Use of a process according to any of the preceding claims for the preparation of a substrate coated with a graphene-containing thin film comprising from 3 to 10 layers of graphene.30. Use of the process according to any of the preceding claims for the preparation of a substrate having one or more layers of graphene deposited thereon wherein the substrate comprises a moulded part, a part-mould, a complete mould, an entire device, a component for a device, or a wafer, and wherein the substrate material is independently selected from: plastic materials; flexible plastic materials; clear plastic materials; thermoplastic polymeric materials; transparent plastic materials; silicon; wafers of silicon and/or silicon oxide; ceramic materials; glass; textiles; wafers.31. Use of a layered-substrate according to any of Claims 29 or 30 in the production of semiconductors, or in the production of semi-conductor components.32. Use of a layered-substrate according to any of Claims 29 or 30 in the production of electrical conductors, or in the production of components for electrical conducting products.33. Use of a layered-substrate according to any of Claims 29 or 30 in the production of a medical device, or in the production of one or more components for a medical device. 45 34. Use of a layered-substrate according to any of Claims 29 or 30 in an FET sensor.35. A manufacturing system for the production of a layered substrate in accordance with Claims 29 or 30. 50 36. Apparatus for use in the process in accordance with any of claims 1 to 25.Amendments to the claims have been filed as followsCLAIMS1. A low temperature plasma-based 3-stage process operable at room temperature for direct deposition of one or more graphene layers onto a substrate comprising: (a) Plasma deposition of a thin film comprising one or more silicon based graphene-philic layers onto a substrate via plasma enhanced chemical vapour deposition (PECVD) wherein the one or more graphene-philic layers is a thin film of from lOnm to 1000nm in thickness; (b) Plasma deposition onto the layered substrate from (a) with a carbon source to provide one or more carbon-containing layers on the substrate via plasma enhanced chemical vapour deposition (PECVD) wherein the one or more carbon-containing layer is an amorphous nanocarbon film; (c) Laser treatment of the layered substrate from (b) using a laser beam to convert the amorphous nanocarbon film to one or more graphene layers; and wherein the temperature does not exceed the melting temperature of the substrate and wherein the temperature is from room temperature to 99°C.2. A low temperature plasma-based 3-stage process operable at room temperature for direct deposition of one or more graphene layers onto a substrate comprising: (a) Plasma deposition of one or more silicon based graphene-philic layers onto a substrate cr) 20 via magneto luminous chemical vapour treatment (MLCVD), wherein the one or more graphene-philic layers is a thin film of from 10nm to 1000nm in thickness; a)O 3. 4. 5. 6. 7.(b) MLCVD treatment of the layered substrate from (a) with a carbon source to provide one or more carbon-containing layers on the substrate wherein the one or more carbon-containing layers is an amorphous nanocarbon film; (c) laser treatment of the layered substrate from (b) using a laser beam to convert the amorphous nanocarbon film to one or more graphene layers; and wherein the temperature does not exceed the melting temperature of the substrate and wherein the temperature is from room temperature to 99°C.A process according to Claim 1 or 2 wherein the heat generated by the laser is sufficient for the conversion in step (c).A process according to any of the preceding claims wherein the temperature at each stage is independently selected: from 50°C to 99°C; from 30°C to 40°C.A process according to any of the preceding claims wherein the graphene-philic layer is a thin film comprising one or more layers of Si0", SiCy, or Si0"(C1 to C4)alkyl layer wherein x and y have values from 1 to 4.A process according to any of claims 1 to 5 wherein the graphene-philic layer is an organic silicon containing material.A process according to any of the preceding claims wherein the pressure in step (a) is in the range of from 10-2 mbar to 101 mbar.8. A process according to any of the preceding claims wherein in step (a), oxygen and silicon-based material are introduced in gaseous form, and wherein the gas flow rates for both are independently selected from 1 sccm to lOsccm.9. A process according to any of the preceding claims wherein for PECVD or MLCVD glow discharge parameters for plasma polymerisation in step (a) are from 5watts to 100watts.10. A process according to any of claims 1-4 wherein the silicon-based matrerial is an organic silicon containing material independently selected from linear and cyclic siloxanes.11 A process according to any of claims 1-4 wherein the silicon-based material is an organic silicon containing material independently selected from: trimethylsilane (SiC3I-18); tetramethylsilane (Si(CH3)4); methoxymethyltrimethylsilane(CH3OCH2Si(CH3)3); 1,1,3,3-tetramethyldisiloxane ([(CH3)2Si1-1]20).12. A process according to any of claims 1-4 wherein the silicon-based material is silane or disilane.13. A low temperature 2-stage plasma-based process operable at room temperature for direct deposition of one or more graphene layers onto a silicon containing substrate comprising: (r) 25 (i) Plasma deposition onto the substrate with a carbon source to provide a thin film C\I comprising one or more carbon-containing layers wherein the thin film is an amorphous nanocarbon film via plasma enhanced chemical vapour deposition (PECVD); O (ii) Laser treatment of the layered substrate from (i) using a laser beam to convert the a) 30 amorphous nanocarbon film to one or more graphene layers; and 0 wherein the temperature does not exceed the melting temperature of the substrate and wherein the temperature is from room temperature to 99°C.14 process according to Claim 13 wherein plasma deposition is carried out via magneto luminous chemical vapour treatment (MLCVD).15. A process according to any of the preceding claims wherein the carbon source is independently selected from: methane (CH4); ethylene (C2H4); ethane (C2H6); carbon monoxide (CO); carbon dioxide (CO2); 2,2-dimethylpropane (C5H12); propadiene (C61-14);1,2-butadiene (C4H6);1,3-butadiene (C4H6);2-methylpropane (C4H10); cyclopropane (C3H6); propene C3116); toluene (C7118); benzene (C6H6).16. A process according to any of the preceding claims wherein the amorphous nanocarbon film is a thin film of from 10 to 1000nm in thickness.
17. A process according to any of the preceding claims wherein the pressure in step (b) or step (i) is in the range of from 10-2 mbar to 10.1 mbar.
18. A process according to any of the preceding claims in step (b) or step (i) hydrogen and carbon source gas are introduced in gaseous form and wherein the gas flow rates for both are independently selected from 1 sccm to lOsccm.
19. A process according to any of the preceding claims wherein for PECVD or MLCVD glow discharge parameters for polymerisation in step (b) or step (i) are from 5watts to 100watts.
20. A process according to any of the preceding claims wherein the wavelength of the laser in step (c) or step (ii) is in the range of from 1080nm to 248nm.
21. A process according to claim 20 wherein the laser in step (c) or step (ii) is a visible, an IR, or a UV laser.
22. A process according to any of the preceding claims wherein the laser in step (c) or step (ii) has a power level in the range of from 1 to 5 Watts.
23. A process according to any of the preceding claims wherein a single layer of graphene is deposited onto the substrate in step (c) or step (ii).
24. A process according to any of the preceding claims wherein a 2-dimensional monolayer of graphene is deposited onto the substrate in step (c) or step (ii).
25. A process according to any of the preceding claims wherein a 3-dimensional, or stacked-structure of up to 10 layers, or from 1 to 6 layers of sp2 carbon atoms arranged in a hexagonal lattice shape wherein each layer comprises a 2-dimensional monolayer, and the layers are stacked one on top of the other is deposited onto the substrate in step (c) or step (ii).
26. A process according to any of claims 13 to 25 wherein the silicon containing substrate material is independently selected from: silicon; wafers of silicon and/or silicon oxide; glass.
27. A process according to any of claims 1 to 12 wherein the substrate material is independently (.0 25 selected from non-silicon containing materials independently selected from: plastic materials; flexible plastic materials; clear plastic materials; thermoplastic polymeric materials; Ntransparent plastic materials; ceramic materials; textiles; wafers.
28. Use of a process according to any of the preceding claims for the preparation of a substrate coated with a graphene-containing thin film comprising from 3 to 10 layers of graphene.
29. Use of the process according to any of claims 1 to 27 for the preparation of a substrate having one or more layers of graphene deposited thereon wherein the substrate comprises a moulded part, a part-mould, a complete mould, an entire device, a component for a device, or a wafer, and wherein the substrate material is independently selected from: plastic materials; flexible plastic materials; clear plastic materials; thermoplastic polymeric materials; transparent plastic materials; silicon; wafers of silicon and/or silicon oxide; ceramic materials; glass; textiles; wafers.
30. Use of a layered-substrate produced by the process according to any of Claims 28 or 29 in the production of semi-conductors, or in the production of semi-conductor components.
31. Use of a layered-substrate produced by the process according to any of Claims 28 or 29 in the production of electrical conductors, or in the production of components for electrical conducting products.
32. Use of a layered-substrate produced by the process according to any of Claims 28 or 29 in the production of a medical device, or in the production of one or more components for a medical device.
33. Use of a layered-substrate according to any of Claims 28 or 29 in an FET sensor.