HexSeed, a UK startup developing diamond coatings for power electronics, has raised over €700k to attack one of AI’s quietest bottlenecks: the heat wasted when data centers convert power.
Carbon13 led the round, with Net Zero Technology Centre and Vento Ventures participating, and the raise unlocks a provisional Innovate UK Partnership Grant.
HexSeed was founded in late 2025 by Mark Tandy, Dr Leonardo Santoni and Dr Michael Glerum, and works with the University of Bristol. Its process grows diamond directly on finished GaN power devices at low temperature via microwave plasma. That matters because diamond is the best-known thermal conductor, yet conventional growth ruins completed chips with heat – which kept the idea theoretical until now.
GaN converts power far more efficiently than silicon but runs hot, and that heat caps its potential. HexSeed’s first market is data center power conversion hardware, a spot the IEA expects to consume 945 TWh by 2030 as AI workloads climb.
“Data centres are on track to consume a significant share of UK grid capacity within the decade, and a large proportion of that energy is lost as heat,” said CEO Tandy.
The funds will take the coating from laboratory demonstration to working GaN devices and pilot customer engagements – a small check chasing a very large efficiency prize.
