Summary
● Semiconductor materials are any materials with characteristics that fall between those of insulators and conductors.
● Pure semiconductor materials are germanium (Ge), silicon (Si), and carbon (C).
● Silicon is used for most semiconductor devices.
● Valence is an indication of an atom’s ability to gain or lose electrons.
● Semiconductor materials have valence shells that are half full.
● Crystals are formed by atoms sharing their valance electrons through covalent bonding.
● Semiconductor materials have a negative temperature coefficient: As the temperature rises, their resistance decreases.
● Heat creates problems with semiconductor materials by allowing electrons to break their covalent bonds.
● As the temperature increases in a semiconductor material, electrons drift from one atom to another.
● A hole represents the absence of an electron in the valence shell.
● A difference of potential, applied to pure semiconductor material, creates a current flow toward the positive terminal and a hole flow toward the negative terminal.
● Current flow in semiconductor materials consists of both electron flow and hole movement.
● Doping is the process of adding impurities to a semiconductor material.
● Pentavalent materials have atoms with five valence electrons and are used to make N-type material.
● Trivalent materials have atoms with three valence electrons and are used to make P-type material.
● In N-type material, electrons are the majority carrier, and holes are the minority carrier.
● In P-type material, holes are the majority carrier, and electrons are the minority carrier.
● N- and P-type semiconductor materials have a higher conductivity than pure semiconductor materials.