There are various methods to produce graphene materials, such as mechanical exfoliation of graphite, liquid-phase exfoliation and reduction of graphene oxide (GO), each with its own set of advantages and disadvantages. Chemical vapor deposition (CVD) is a method of producing graphene that has attracted much attention in the last decade and despite several shortcomings, is considered a leading approach to manufacture graphene, especially for applications like high-performance electronics and sensors, as it can yield high quality graphene sheets with a low defect count and good uniformity.
The CVD process
Generally speaking, the CVD method is based on gaseous reactants that are deposited on a substrate. The graphene is grown on a metallic surface like Cu, Pt or Ir, after which it can be separated from the metal and transferred to specifically-required substrates. When the gases contact the substrate inside the heated reaction chamber, a reaction occurs that creates a film of material on the substrate. The process can be simply explained as carbon-bearing gases that react at high temperatures (900–1100 °C) in the presence of a metal catalyst, which serves both as a catalyst for the decomposition of the carbon species and as a surface for the nucleation of the graphene lattice.
As was mentioned before, conditions like temperature, pressure, duration of time and many more can have a significant influence on the process and so must be carefully monitored.
Advantages and disadvantages
CVD can yield high quality graphene, with common characteristics that may include high homogeneity, imperviousness, high purity, fine grains, good control over layer number and more. However, CVD also comes with several disadvantages - namely a relatively high price of the equipment, toxic gaseous by-products and, as stated before, it is a rather sensitive process that is easily influenced by parameter changes. It is important to note that while CVD is a rather expensive method compared to other methods to produce lower-quality graphene, it is still probably the best way (to date) to acquire high quality graphene, since other ways to do that are even more expensive or complicated.
In addition, the separation (or exfoliation) of graphene from the substrate is known as challenging and it is tricky to accomplish without damaging the structure of the graphene or affecting the properties of the material. Another harrowing task is the creation of a uniform layer of graphene on a substrate, something that is continuously proving to not be easy at all.
Some approaches were and are still being developed to overcome this issue, like modifying the concentration of gases and incorporating spin coating methods, but this remains a challenge. However, despite these challenges, it is important to note that CVD is widely considered as an important and promising method to produce graphene, which is already in use, and will probably be even more so in the future, once further advancements are made. It is noteworthy that CVD is already a dominant manufacturing route for many other nanomaterials, and will assumably be in extremely common use once progress is made to resolve the issues that are currently hindering its acceptance.
While using the CVD method to produce graphene is definitely one the leading approaches in the world, it is still hindered by the challenges mentioned above. Thus, it is currently mostly limited to relatively small volumes and mainly restricted to R&D and academic uses.
However, graphene sheets produced via CVD methods are used in several applications like sensors, touch screens and heating elements. It is believed that once better answers are found to the questions of price and handling of CVD graphene, many more applications will start to appear.
Looking to buy CVD graphene sheets?
If you are interested in buying CVD graphene sheets, check out the Graphene Catalog that lists various CVD produced graphene sheets from several producers.
The latest CVD graphene news:
Our friend Dr. Khasha Ghaffarzadeh, a well respected graphene market analyst, is launching a new service called TechBlick that is a subscription-based online and all-year round event focused on advanced materials such as graphene, 2D materials, CNTs, boron nitrides, QDs, and more.
Graphene-Info partnered with TechBlick, to provide our readers an exclusive 25% discount on the TechBlick subscription. We took advantage of this launch to discuss the graphene market and industry with Dr. Ghaffarzadeh and also discuss the new service.
Hello Kasha. How do you see the graphene market shaping up in 2021?
I have closely followed and examined the graphene industry for a full decade. The landscape has certainly changed. Many companies have come and gone, and many once considered revolutionary applications are now ruled out, but overall, the industry is now at a tipping point.
We think 2021/2022 will be a turning point, setting the industry on its growth path, despite the delays caused these past 12 months due to Covid. For some, these delays have been painful as projects were pushed back or partners or customers dropped graphene to focus on other core areas. Many undershot their growth expectations, and some had difficult cash flow situations.
GraphAudio was established in 2016 to commercialize graphene-based acoustic products based on technology that originated from UC Berkeley and Berkeley Lab. GraphAudio's technology enables electrostatic micro transducers that use CVD graphene sheets.
GraphAudio's CEO is Ramesh G. Ramchandani, that previously held executive leadership positions at International Rectifier, Semicoa, nPlay Technologies, ZiLOG and ON Semiconductor. The company is a senior advisor for consumer and commercial AI at Google X. Following is an interview with Ramesh to discuss GraphAudio's technology, business and roadmap.
UK-based planarTECH has recently concluded a successful an equity crowdfunding campaign, as part of Graphene-Info's Graphene Crowdfunding Arena. The company's CEO, J. Patrick Frantz, was kind enough to answer a few questions we had and give his advice for graphene companies that consider the equity crowdfunding option.
Thank you for this interview. You have recently concluded a successful graphene crowdfunding campaign. Well done. Can you summarize this experience for us?
Well, given the current situation with COVID-19, it was certainly an emotional rollercoaster ride to get through the crowdfunding. If I recall correctly, we launched the campaign in “private” live mode in January as the pandemic started to unfold. We stayed in private mode for a while but finally went “public" in March as the crisis was reaching its most severe point in Europe.
ESA-backed researchers from Delft University of Technology in the Netherlands and SCALE Nanotech in Estonia have demonstrated the laser-propulsion of graphene sails in microgravity.
As demonstrated first by JAXA's mission IKAROS (2010) and recently by The Planetary Society's LightSail 2 (2019), using light sails as propulsion system is among the most promising ideas to enable fast and affordable space trips. Not only sails do not require fuel to move, but they save its corresponding costly weight and that of its containing tanks.
planarTECH's graphene crowdfunding campaign reaches 100%, investors are still welcome to participate
UK-based planarTECH has recently launched an equity crowdfunding campaign on Seedrs, as part of Graphene-Info's Graphene Crowdfunding Arena. We are happy to announce that the campaign reached 100% funding today. You can still take part in this exciting campaign, as PlanarTECH still accepts new investors via Seedrs.
PlanarTECH supplies Chemical Vapor Deposition (CVD) systems for the growth of graphene, and has already installed over 65 systems worldwide, to customers such as the University of Manchester, the University of Cambridge, Stanford University and the National University Singapore.