3D white graphene could prevent electronics from overheating

Heat dissipation, or at least the tunable control of heat, is a major headache in electronics. Now researchers have proposed a complex 3D structure made from a 2D material, known as white graphene, which may provide a solution to this problem.
Normally, graphene is a 2D, one-atom thick layer of carbon in a hexagonal lattice. Its heat transfer capabilities are superb, but it’s also an electrical conductor — an extremely good one, in fact. Hexagonal boron nitride (h-BN), on the other hand, is similar to graphene (known as white graphene) in that it’s a one-atom thick layer, yet it’s also an electrical insulator. This property makes such structures may be suitable for controlling heat flow in electronics.
The researchers have proposed, as well as computationally simulated, a 3D thermal management solution based on white graphene for next-generation 2D electronics. Normally, it is desirable to dissipate the heat from the system quickly, efficiently, and without the need for complex design schemes. For electronics, whereby we are approaching the level of ~2D, single-to-few-atom-thick stacked layers, heat transfer usually occurs along a conductive plane (2D). Hence, heat out-of-plane conductivity is poor. This creates a heat buildup problem, severely limiting high-speed electronics, and a 3D solution to this problem has remained elusive.
When one describes heat, the picture of a ‘phonon‘ is used. If a photon is a quantized excitation of the electromagnetic field, then a phonon is simply the name given to the quantized excitation of the vibrational motion of atoms. Interestingly, it is not really a particle — it’s a quasi-particle and exists only in a vibrational mode. Nevertheless, in h-BN, this phonon (heat mode) can move ballistically across the 2D flat planes; the problem is still out-of-plane.

3D hexagonal Boron Nitride for potentially tunable heat transfer capability at the nanoscale

What the Rice University researchers showed is that 3D structures of h-BN planes connected by BN nanotubes (see above images) would allow heat transfer in all directions — not just across a 2D plane. The researchers modeled a range of structures with different geometries in order to obtain the optimal heat transfer properties. The combination of 2D single-atom-thick sheets and nanotubes provides a way to transfer heat in any desirable direction, dependent on the location and design of the resulting 3D structure.
The researchers observed that the junctions between the 2D sheets and the nanotubes reduced the heat flow, but that longer nanotubes enabled greater heat flow between layers, whilst shorter nanotubes tended to slow down heat conduction. These junctions of pillars and planes acted like “yellow traffic lights, not stopping but significantly slowing the flow of phonons from layer to layer”.
This is the first work of its kind on thermo-mutable properties of BN for use as a complementary element for 3D heat transfer in 2D nano-scale electronic circuitry. Thanks to its excellent chemical and thermal stability, the integration of such structures in advanced electronic architecture may not be as problematic. The next challenge: fabricating and synthesizing such structures, either in isolation, or in combination with typical CMOS techniques.
Paper: pubs.acs.org/doi/abs/10.1021/acsami.5b03967