"What if electronic bottlenecks didn't exist, and data could be transferred seamlessly between chips?" This is the question that Cédric Huyghebaert, CTO and co-founder of Black Semiconductor, uses to encapsulate the ambition of one of Europe's most innovative photonics startups. At PIC Summit Europe 2025 in Eindhoven, he explained how the company leverages the unique properties of graphene to directly integrate photonics into semiconductor manufacturing. "We call it a new kind of chip," he said, "because now, your CMOS chip can speak two languages simultaneously: electronics and photonics."

From Lab to Factory: The Long Road of Graphene

"When we started working on graphene," Hugh Barth recalls, "everyone thought we'd found the new silicon." With its extraordinary mobility and conductivity, researchers envisioned graphene completely replacing CMOS transistors. "But luckily," he says with a laugh, "graphene has no band gap. It has a peculiar band structure, and that ultimately became our advantage."

He explains that early experiments were simple: peeling off an atomically thin layer of graphene in the lab. "We shone light on it and found it absorbed 2.3% of the light; that's a lot for a single layer of graphene, but not enough to make a device." The key breakthrough came when scientists laminated graphene onto waveguides, allowing light to repeatedly interact with the graphene layer. "This way you can tune the absorption rate, even absorb all the light as needed," Hugh Barth says.

This discovery opened the door to the development of graphene modulators and photodetectors, devices capable of manipulating and detecting light at astonishing speeds. "It performed brilliantly in the lab," he says. "But how do you connect it to electronics? How do you scale it up? That's what Black Semiconductor was founded for."

A new category of chips: EPIC chips, not just PIC chips

Traditional approaches to merging photonics and electronics rely on complex and costly advanced packaging technologies: bonding, thinning, and stacking multiple chips. "It's incredibly complex," Huyghebaert says. "Our proposed alternative is EPIC: Electro-Photonic Integrated Circuits. We integrate these two technologies using standard industrial processes. No stripping processes or special tools are required." The result is revolutionary simplicity: photonic devices that can be fabricated within standard CMOS production lines allow data transmission to be achieved via light, no longer relying on electronics. "Whatever you build on the chip underneath," he says, "it suddenly communicates in two languages. It can do both electronic computing and optical communication. It's a game-changer." 

Challenges: Quality, Repeatability, Scalability

Graphene's potential is no less than its challenges. "You can't just go to a foundry and have them integrate graphene onto a chip - at least we haven't found one yet," admitted Hugh Barthes. What are the main problems? Quality and repeatability. "Graphene is known for its excellent performance, but its stability is poor," he said. "So we're developing single-crystal graphene, growing it first on 200mm wafers, and then scaling up to 300mm. This is crucial for stability." The transfer process is also very tricky. "We grow graphene on a template and then transfer it to the wafer, but keeping it flawless is difficult. Repeatability has been a key bottleneck in the history of CMOS technology until the industry mastered methods to control the gate oxide layer. Now, we have to do the same with graphene." The third challenge is scalability. "Even if this technology succeeds, can we produce 100,000 wafers a year? 1 million?" he asked. "If you want to apply photonics to every chip, you need to develop a large-scale production plan."

Europe's Graphene Moment

Aachen-based Black Semiconductor found its answer through collaboration with Europe. "Europe has a deep-rooted tradition in graphene research," Huyghebaert reminded the audience, citing the EU's Graphene Flagship program. "So, in 2021, we began dialogue with policymakers, persuading them that Europe should keep this technology domestically." Their proposal was successful. In June 2024, Black Semiconductor received funding from IPCEI (Important Projects in the Common European Interest) to build a 300mm integrated graphene photonics pilot production line. "We are currently designing the wafer fab," Huyghebaert said, "It will be operational by mid-2026, fully operational by early 2027, and product samples will be available soon."

The company's growth has been equally rapid. "In 2022 we only had two people," he said, "now we have 130, and next year we will reach 240." Such rapid growth has also brought challenges. "Recruiting talent is difficult," he admitted, "but getting the right people to do their jobs is even more difficult. Newcomers need time to become efficient; that's exactly what we're working on right now."

Beyond Silicon Photonics

Today's silicon photonics (SiPh) technology - the mainstay of optical interconnects - faces numerous limitations when integrated into the back-end processes (BEOL) of chip manufacturing. "SiPh requires high temperatures and materials incompatible with BEOLs," explains Huyghebaert. "Graphene, in contrast, is a perfect fit. It operates at low temperatures, is compatible with CMOS processes, and enables high-speed modulators and detectors."

He believes this compatibility can redefine computer architecture. "It allows us to rethink how chips communicate; directly through light, within the same stack. This is how we break through the interconnect bottlenecks that hinder the development of artificial intelligence."

In the company's vision video, he succinctly summarizes: "Graphene photonics eliminates electronic bottlenecks, enabling limitless data throughput." 

Next Steps: Glass and Light

Black Semiconductor is also developing glass panel interposers, an emerging next-generation computing platform. "Glass can reduce signal loss, increase bandwidth, and support more complex system architectures," says Huyghebaert. "Combined with integrated graphene photonics technology, it can create seamless optical structures between chips." In early lab tests, their graphene modulator has already demonstrated impressive speeds: currently at 5 GHz, with plans to achieve modulation speeds of 20-25 GHz and photodetectors at 60 GHz. "We're just getting started," he says, "but we know where we're headed." 

Towards the Post-Silicon Era

Finally, Sugarbart mentioned his last academic paper before founding Black Semiconductor. "The title was 'Two-Dimensional Materials Make Back-End Production Lines Smarter.' And that's exactly what we're doing: making back-end production lines smarter."

He said their goal isn't to replace CMOS, but to enhance it, turning the back of the chip into an active optical layer. "This is the first product of a new type of chip. Electrons and photons are truly integrated. This is how we rethink computing." Sugarbart's message is clear: the next revolution in computing won't just come from faster transistors; it will come from light, light flowing through a single layer of carbon.

Source: Content from ioplus

Reference link: https://ioplus.nl/en/posts/the-graphene-revolution-that-could-redefine-computing

View more at EASELINK