Here again is what an AI replied.
"You’re right that GaAs can run at extremely high frequencies — RF GaAs devices routinely operate in the 50–250 GHz range because of their high electron mobility. That part isn’t disputed.
But that doesn’t contradict the CPU clock limit. The ~4–5 GHz ceiling is a silicon CMOS logic problem, not a universal semiconductor limit.
GaAs isn’t used for CPUs because it has several hard blockers:
- Low integration density — you can’t pack billions of logic transistors like you can with silicon CMOS.
- No high‑quality native oxide — silicon has SiO₂, which makes CMOS possible; GaAs doesn’t.
- Poor thermal conductivity — GaAs is ~50 W/m·K vs silicon at ~150 W/m·K, so it removes heat worse.
- High cost and low yield — GaAs wafers are expensive and don’t scale to CPU‑class complexity.
- Great for RF, terrible for dense logic — GaAs excels at microwave/millimeter‑wave front‑ends, not general‑purpose processors.
So yes, GaAs can hit 100+ GHz, but you can’t build a modern CPU out of it. The 4 GHz wall is specifically a silicon CMOS switching/voltage/leakage/thermal limit.
Modern CPUs get faster through IPC, architecture, and parallelism — not higher GHz."
Can we trust the AI response? I don’t have enough knowledge to question the answer and performing searches on the internet can be very time consuming.
So I was wondering where in the hell did all this info come from so again I asked AI to provide a reference list of the information that was provided.
" * IEEE Transactions on Electron Devices
- Cambridge University Press – Compound Semiconductor Device Physics
- MIT OpenCourseWare – Microelectronic Devices and Circuits
- Nature Electronics
- CRC Handbook of Chemistry and Physics
- Journal of Applied Physics
- Semiconductor Industry Association (SIA)
- IEEE Spectrum
- Wiley – RF Microelectronics
- IEEE Microwave Magazine"