gallium arsenide (GaAs) has six times higher electron mobility than silicon, which allows faster operation... Conversely, silicon is robust, cheap, and easy to process, whereas GaAs is brittle and expensive, and insulation layers can not be created by just growing an oxide layer; GaAs is therefore used only where silicon is not sufficient.
-- WikipediaOne advantage of native III-V substrates is they are semi-insulating (very high resistivity) so there is no need for transistor isolation wells. However, insulated substrates could be obtained on silicon by means of wafer bonding with an intermediate dielectric layer.
I know I'd be keeping specifics as tightly controlled as possible until the last moment. It's one of those rare big jumps that really separate the players in the field.
It's a scary time for the industry, as Moore's law comes to an end.
(All that said, even if no one knows for sure what's coming next, that doesn't mean nothing will. The semiconductor industry is throwing billions of dollars and thousands of engineers at many potential solutions in parallel. Even if plan A falls through, there is always a heavily researched plan B, C, and D.)
I also note that Seymour Cray wanted to do gallium arsenide CPUs back in the late '80s: https://www.youtube.com/watch?v=xW7j2ipE2Ck .
By the way, an interesting alternative to blasting drops of molten tin in vacuum is to just build a multimillion dollar synchrotron and use its x-rays for lithography in a fab. This has a whole bunch of other problems, but it's an idea that engineers are seriously considering.
Most of my knowledge comes from my friend who used to work on the problem of inspecting x-ray masks.
Static RAM cells haven't scaled for about two generations now, but you could still scale functional transistors.
Now, even that is stopping. Moore's Law was more an economic law than a physical one.
Exponential growth has to run out sometime.
I don't know.. people said the same thing when clock rates got close to 4Ghz. We always seem to find ways to work around physical limits.
Things actually broke at 90nm. Gate leakage went up enough that most analog/RF circuits scaled their transistors back up to 130-150nm dimensions while the digital guys cashed in the density increase one last time.
65nm was the first node where static RAM cells didn't scale with the rest of the digital circuitry. RAM cells are more sensitive to leakage since they have a "writability constraint" where you have to be able to shove enough electrons from outside the cell, through a transistor, with enough oomph to change the state inside the RAM cell.
40nm was where RAM scaling really broke. Designers had to start jumping through amazing hoops to support tricks for the manufacturing guys to eke out the last jump even for standard digital circuits. Most technologies started trading off multiple gate oxide thicknesses to manage leakage current.
28nm was where everything basically went to hell. The strong form of Moore's Law (twice the transistors for same cost) broke. RAM cells are way off the scaling curve. Leakage is everywhere. Multiple gate oxide thicknesses are the rule, not the exception. Designers are jumping through tremendous hoops for manufacturing (aligning all gates in the same direction over the entire chip, for example).
Below 28nm has been a disaster, and, as pointed out, a lot of the sub-28nm stuff is more marketing than actual physical dimensions.
http://electroiq.com/blog/2014/02/the-most-expensive-sram-in...
I don't see that as a bad thing. There's plenty of optimization opportunities on the software level. Think of the difference between first-generation and last-generation console games.
eg Rainbow[0], BORPH[1], Mill architecture[2]
http://spie.org/AL/conferencedetails/alternative-lithographi...