Don't you need the defects to have semi conductors? I seen some really cool experiments with superconductors and every computer works better cold. Isn't that why Google's quantum computer is supercooled?
No. However, most of the time you want doped semiconductors and doing that introduces defects. The defects are bad for resistive losses but that's life.
> every computer works better cold
No. Conventional electronics based on doped semiconductors don't work below a certain temperature because the impurities are "frozen". There is a sweet spot of temperatures that works best. The purpose of cooling on a computer is to keep the temperature as close to the sweet spot as possible.
> Isn't that why Google's quantum computer is supercooled?
Quantum computers like Google's rely on superconducting materials (most of) those require sub-Kelvin temperatures to work, both to reach the superconducting regime and to reduce phonon induced decoherence. Superconductivity works in quite a different way to conventional materials to conductivity in semiconductors and metals too.