text: * Electronics
  * Bandgap voltage reference
  * Condensed matter physics
  * Direct and indirect bandgaps
  * Electrical conduction
  * Electron hole
  * Field-effect transistor
  * Light-emitting diode
  * Photodiode
  * Photoresistor
  * Photovoltaics
  * Solar cell
  * Solid state physics
  * Semiconductor
  * Semiconductor devices
  * Strongly correlated material
  * Valence band