Also the semiconductor industry, and ultimately the Silicon Valley, had their origin in WWII, in the great effort for developing technologies for making germanium and silicon crystals with extremely low levels of impurities and defects, which were needed for diode detectors in radars.

The vacuum diode detectors used in radios before WWII did not work at the high frequencies required in radars. Most of the work for semiconductor technologies had been done at Bell Labs, which after the war used this for developing other semiconductor devices.