- 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