• They have the conductivity between conductors (metals) and non conductors/insulators (non-metals)
  • Basically semiconductors are metalloids
  • They can conduct a small amount of electricity
  • Popular examples are silicon and germanium

Temperature and conductivity

• Semiconductors conduct better at higher temperatures
  • We can dope (add impurities) to a semiconductor to increase its conductivity
• Conductors conduct better at lower (colder) temperatures

Types of semiconductors

• Intrinsic (pure aka not doped)
• Extrinsic (impure aka doped)

Doping

• The process of adding impurities to an element to create an extrinsic semiconductors

N-Type semiconductor (Example: Silicon)

• N-Type semiconductors are called negative type semiconductors
• The crystalline structure of silicon is that one silicon is covalently bonded to 4 other silicon atoms

• if you dope silicon with an element that has one more electron, say phosphorus (has 5 valence electrons) then the phosphorus will have 4 covalent bonds with the silicon and one electron will still be remaining
• This remaining electron is free to move, and it can move to the conduction band
  • This increases its conductivity

• The charge carriers of N-Type semiconductors are electrons

P-Type semiconductors (Example silicon)

• P-Type semiconductors are called positive type semiconductors
• Let’s say you dope silicon with an element that has lesser valence electrons, like aluminum with 3 valence electrons