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1: 108 concentration approx teaspoon / swimming pool
1: 108 concentration approx teaspoon / swimming pool
1940 PN junction diode discovered Russel Ohl, Bell labs
Investigating Cat’s whisker detectors
Noticed conduction through crystal of germanium he’d grown changed on exposure to light. Crack in crystal due to differing impurities in 2 halves of crystal during growth.
Walter Brittain deduced ‘junction’ at crack – semiconduction
Within 1 year germanium diodes for radar sets
Junction needs to be in single crystal, diffuse in dopants