[NovaVeles]

I am not so keen on photon transistors, at least not in the short term. I have seen them proposed for decades but progress has been slow at best. Maybe some folks will figure it out and we will make that leap but current progress is not looking great. As for Carbon nano tubes, I'm not too familiar with the applications of this for transistors but it does sound like something that can get us a little further down the road.

All this arm chair speculation. All the people that work on these things would know far better than me. And I mean ALL the people! ;)

[dotnet00]

I agree regarding photonic transistors, I have a hard time seeing how those would scale down to even current transistor sizes/densities. Especially given that they'd probably have to rely on much shorter wavelength light, which comes with its own issues.

Carbon Nanotube transistors are fairly promising though, they're structured similarly to regular transistors but can have some neat properties like ballistic transport regimes (meaning zero resistance when enough current is going through), better heat dissipation and ability to handle much higher currents. IIRC they're also very tunable with the bandgap controlled by the shape of the tube.

Main issue with CNT transistors is just that - as with most things involving CNTs - we need production methods that are significantly more consistent with the shape and quality of tube they produce. We'd need to be able to print billions of tubes per chip with almost the exact same shape to compete with traditional semiconductors.