For companies evaluating graphene for commercial integration, quality is not a specification sheet — it’s a risk management question.

We sat down with Graphenea’s CSO to discuss what truly defines high-quality graphene, why reproducibility matters more than peak performance, and how industrial customers should evaluate suppliers.

Amaia Zurutuza, Chief Scientific Officer at Graphenea.

“In graphene, the average matters more than the best sample.”

Q: When customers ask about graphene quality, what are they usually missing?

Amaia:
Most people ask, “Is it monolayer?” That’s a starting point — but it’s not enough. The real question is: How uniform is it across the entire wafer? Across batches? Across months?

In research, a single high-performing device can be exciting. In industry, you need statistical consistency. The average performance — and the deviation from it — determines yield.

Q: Is it important to state that graphene is monolayer across a wafer?

Amaia:
Monolayer graphene behaves very differently from bilayer or multilayer graphene. That’s physics. But what matters in manufacturing is how consistently you achieve that layer count across a 4-inch or 8-inch wafer.

We rely heavily on a combination of characterisation techniques (Raman spectroscopy, OM, AFM, SEM, TEM, etc.) to ensure the quality of the monolayer graphene that we fabricate.

Q: How do you explain defect density to industrial buyers?

Amaia:
Completely avoiding all types of defects is extremely difficult, the key relies in controlling them.  Each application has its own level of defect density that can be tolerated.

If you’re building RF electronics or high-mobility devices, defects reduce carrier transport. If you’re building sensors, a certain amount of defects can be tolerated.

We evaluate crystalline integrity using the Raman ID/IG ratio. Lower ratios indicate fewer structural defects.

Consistency across batches is what industrial customers should look for — not just a single impressive number.

Q: How do you measure carrier mobility?

Amaia:
Mobility is often cited in marketing materials. But mobility depends on how you measure it.

Hall measurements, FET extraction, device type, substrate effects — they all produce different numbers.

Industrial customers should ask:

• What measurement method was used?
• Was it intrinsic mobility or device-extracted?
• What substrate?

Mobility is not a universal constant. It’s process-sensitive. We use the transconductance method consistently, and in fact we are about to publish results that we obtained with our partners on the precision of different methods. We show that the selected measurement test structures and analysis methods can have a large impact on the extracted values and should thus be considered when comparing data sets between different sources.

Q: For transparent conductive films or flexible electronics, sheet resistance becomes critical. How do you comment on that?

Amaia:
You can reduce sheet resistance by increasing layer count or doping — but then you change optical transparency or long-term stability.

There’s always a trade-off. Engineering is about balancing those trade-offs intentionally.

Q: What about grain boundaries and domain size? Are those important?

Amaia:
In CVD graphene, growth domains converge. Where they meet, grain boundaries form.

Larger domain sizes mean fewer grain boundaries and better electronic performance.

For quantum or high-frequency applications, this matters significantly. For conductive coatings, it may not.

The key is matching material properties to application needs.

Q: Do graphene samples often contain contamination?

Amaia:
In my experience, contamination during fabrication and transfer causes more real-world performance loss than intrinsic material defects.

These processes need to be carefully and consistently controlled. Polymer residues, metal etchants, ambient adsorption — these impact contact resistance and device reproducibility.

Industrial customers often underestimate the importance of a clean transfer process. We use our patented transfer process to minimize contamination in all our CVD graphene.

Q: Efforts like the Graphene Flagship have helped align academia and industry, but are global grading standards still evolving?

Amaia:
Until formal standards are universal, transparency is everything.

Customers should request:

• Full wafer maps
• Statistical distributions
• Batch reproducibility data

Quality control is not a single metric. It’s a system of metrics.

Q: Do you have any final reflections?

Amaia:
Graphene commercialization won’t be limited by physics. It will be limited by process control and reproducibility.

The companies that succeed will be those who treat graphene manufacturing with the same statistical rigor as semiconductor fabrication. We at Graphenea put a lot of emphasis on standardization and batch-to-batch consistency. It’s built into our production procedures.