4 ms·
The article and paper don't mention it, but the thermal conductivity of single crystal diamond can be increased another 50% at room temperature by using pure ca
by pfdietz 1y ago
The article and paper don't mention it, but the thermal conductivity of single crystal diamond can be increased another 50% at room temperature by using pure carbon-12. The isotopic uniformity reduces scattering of phonons, which are what transports heat energy in diamond. For a very thin film like this the cost of using isotopically purified carbon shouldn't be that bad.
BTW, the thermal conductivity of C-12 diamond at cryogenic temperature is even higher, reaching something like 41000 W/m K at 104 K.
Isotopically purified silicon has also been considered due to its higher thermal conductivity, but the effect there at room temperature is not nearly as dramatic.
Weirdly, I read UV damage in C-12 diamond is reduced by a factor of 10 vs. natural diamond, I understand because this damage process is mediated by phonons. No relevance to the chip use case (unless UV damage in photolithography could be important?), but I found it interesting.
- modeless 1y agoThis is polycrystalline diamond, which probably scatters phonons anyway, so it seems naively like using a single isotope wouldn't help much. But that's definitely an interesting fact and I think you're right that it probably wouldn't add much expense when the amount of material is so small.
- pfdietz 1y agoI'm not sure that's too dominant? The thermal conductivity reported is close to the natural diamond, so increasing the conductivity of the individual microcrystals could still be significant.
- the8472 1y agoI joked about it last year[0], but before going for isotopically pure diamond they first have to make them single-crystal, the grain boundaries are worse than isotopic impurities. [0] https://news.ycombinator.com/item?id=39742447 https://news.ycombinator.com/item?id=39742447
- deleted 1y ago[deleted]