material with electrical conductivity between conductor and insulator
silicon and germanium are the primary elemental semiconductors
doping with impurities creates n-type (electron excess) and p-type (hole excess) regions
p-n junction is the fundamental building block: diode, transistor, solar cell
transistor: switch and amplifier, basis of all digital computing
Moore's law: transistor density doubles approximately every two years
fabrication: lithography, etching, deposition, ion implantation in cleanrooms
enables battery management, antenna signal processing, engine control units
compound semiconductors (GaAs, GaN, SiC) for high-frequency and high-power applications
the material substrate of planetary superintelligence and cyberia infrastructure