Beyond Graphene: When should h-BN be used instead of graphene

Many people talk about graphene, its properties, its applications, and its global potential. However, graphene is just one of many hundreds of 2D materials out there (and there are even different types of graphene (but that’s for another day).

Many of which have just as much potential as graphene. In some cases, it is possible to combine graphene with the other 2D materials to obtain synergistic effects not seen with other materials.

Nevertheless, despite the potential of other 2D materials, they don’t get as much coverage as graphene.

Outside of graphene, one of the 2D materials that shows some of the most promise, both in terms of properties and commercial developments, is hexagonal boron nitride (h-BN).

I recently caught up with Jeff Draa from Grolltex, A U.S. manufacturer that produces both CVD graphene and h-BN, to discuss how h-BN developments are coming along and what the future potential of the 2D material world beyond graphene looks like.

For those who are new to 2D materials, could you please describe the fundamental differences between graphene and hexagonal boron nitride (h-BN).

In the case of monolayers of each of these materials, some similarities are that both can be produced in the same piece of equipment using CVD (chemical vapor deposition) and that both have a near identical atomic structure.

So, they are very compatible when layered one on top of the other (and there can be many reasons to want to do this).

An important difference is that graphene is a highly conductive material and h-BN is an electrical insulator, so it is pretty much the opposite of graphene in this regard.

It’s a little bit like holding a wire in your hand; you wouldn’t want to do that unless the copper inside were shielded by the rubber cover on the outside. You need both.

This can be key when using these materials together, because often, advanced electronics designers need both types of materials to create nano-devices.

Given the different properties between graphene and h-BN, what applications is h-BN useful for that graphene is not?

In addition to acting as the insulator when called upon, h-BN is also much more transparent than graphene.

So, for applications that require transparency, h-BN is better suited. Also, for advanced biosensing applications, it has been shown that if there is a monolayer of h-BN deposited on the wafer first, followed by a layer of graphene on top of the h-BN, the graphene layer shows a much higher sensing performance than similar architectures that do not have this h-BN layer underneath.

There are some applications where graphene and h-BN can be used together (e.g. in van der Waals heterostructures). What are some of the key applications where both graphene and h-BN can be used together?

As mentioned above, one of the key applications where this is important is advanced biosensing applications.

Next generation tools that enable cancer researchers and new drug developers to ‘see’ and understand things they couldn’t before, can be a very valuable asset.

Some of these areas are being optimized beyond what was thought possible with ultra-performing graphene biosensors resting on layers of h-BN.

Over the years, I’ve heard many people say that h-BN and other 2D materials actually have more promising properties than graphene, but some are much harder to commercialize in large volumes. Would you claim this to be a true statement?

Mostly, I would say this is a true statement, with the caveat that many of these other 2D materials that have the potential to perform better than graphene and/or h-BN could be called ‘exotic’ materials.

This means they are very difficult to produce and therefore may be out of practical usage for a very long time.

By contrast, graphene (and now some are saying h-BN as well) has recently entered the realm of easy and inexpensive to acquire, and therefore commercialize. This is the true advantage of these materials today.

In terms of the future of h-BN and other 2D materials beyond graphene, what is the market potential for these materials and what end-use sectors could we see them being widely used in?

Some of the future market potential growth areas for h-BN, for example, are:

1. Enhancing the performance of other monolayer materials.

2. Transparency related areas such as advanced displays.

3. Surface enhancement or protection as a coating for critical surfaces — e.g. for keeping walls, ceilings, or other surfaces inside surgery rooms germ free, or for improving the fire-retardant characteristics of interior surfaces in airplanes.

In which regions of the world would you say there is the most activity going on surrounding the commercialization, use, and scale-up of h-BN?

For monolayer h-BN, the answer is pretty clearly the U.S.

This is not true, however, for monolayer graphene, where there is so much activity in China, the UK, Korea and the EU. The U.S. is somewhat behind in monolayer graphene activity, but it is slowly catching up. 

On a similar note, graphene is now starting to gain some traction across many different markets, but it has taken some time. Now that the door has been opened to 2D materials in various applications, how long do you think it will take h-BN (and other 2D materials) to reach the levels that graphene is at today?

Hard to say here, as it has taken 10 years for graphene to see the visibility it is now getting.  But with any luck, we should see h-BN traction within the next 5-7 years.

Finally, a question that I ask everyone, what impact do you see graphene and the other 2D materials having on society and what are going to be some of the key areas to look out for in the future?

Monolayer graphene is being used more and more as an advanced biosensing material. There are several modalities where new designs are employing graphene to sense biology faster and in lower concentrations than were thought possible before.

Some of these areas are as a Crispr-Chip for gene editing research and application, in new drug discovery approaches, as advanced glucose sensors, and wearable sensors for continuous blood pressure monitors.

The health sciences will be the first to really open this door. But you will also see advanced photonics sensors and higher-level performing LED’s soon as well.