Key Terms
- acceptor impurity
- atom substituted for another in a semiconductor that results in a free electron
- amplifier
- electrical device that amplifies an electric signal
- base current
- current drawn from the base n-type material in a transistor
- BCS theory
- theory of superconductivity based on electron-lattice-electron interactions
- body-centered cubic (BCC)
- crystal structure in which an ion is surrounded by eight nearest neighbors located at the corners of a unit cell
- breakdown voltage
- in a diode, the reverse bias voltage needed to cause an avalanche of current
- collector current
- current drawn from the collector p-type material
- conduction band
- above the valence band, the next available band in the energy structure of a crystal
- Cooper pair
- coupled electron pair in a superconductor
- covalent bond
- bond formed by the sharing of one or more electrons between atoms
- critical magnetic field
- maximum field required to produce superconductivity
- critical temperature
- maximum temperature to produce superconductivity
- density of states
- number of allowed quantum states per unit energy
- depletion layer
- region near the p-n junction that produces an electric field
- dissociation energy
- amount of energy needed to break apart a molecule into atoms; also, total energy per ion pair to separate the crystal into isolated ions
- donor impurity
- atom substituted for another in a semiconductor that results in a free electron hole
- doping
- alteration of a semiconductor by the substitution of one type of atom with another
- drift velocity
- average velocity of a randomly moving particle
- electric dipole transition
- transition between energy levels brought by the absorption or emission of radiation
- electron affinity
- energy associated with an accepted (bound) electron
- electron number density
- number of electrons per unit volume
- energy band
- nearly continuous band of electronic energy levels in a solid
- energy gap
- gap between energy bands in a solid
- equilibrium separation distance
- distance between atoms in a molecule
- exchange symmetry
- how a total wave function changes under the exchange of two electrons
- face-centered cubic (FCC)
- crystal structure in which an ion is surrounded by six nearest neighbors located at the faces at the faces of a unit cell
- Fermi energy
- largest energy filled by electrons in a metal at
- Fermi factor
- number that expresses the probability that a state of given energy will be filled
- Fermi temperature
- effective temperature of electrons with energies equal to the Fermi energy
- forward bias configuration
- diode configuration that results in high current
- free electron model
- model of a metal that views electrons as a gas
- hole
- unoccupied states in an energy band
- hybridization
- change in the energy structure of an atom in which energetically favorable mixed states participate in bonding
- impurity atom
- acceptor or donor impurity atom
- impurity band
- new energy band create by semiconductor doping
- ionic bond
- bond formed by the Coulomb attraction of a positive and negative ions
- junction transistor
- electrical valve based on a p-n-p junction
- lattice
- regular array or arrangement of atoms into a crystal structure
- Madelung constant
- constant that depends on the geometry of a crystal used to determine the total potential energy of an ion in a crystal
- majority carrier
- free electrons (or holes) contributed by impurity atoms
- minority carrier
- free electrons (or holes) produced by thermal excitations across the energy gap
- n-type semiconductor
- doped semiconductor that conducts electrons
- p-n junction
- junction formed by joining p- and n-type semiconductors
- p-type semiconductor
- doped semiconductor that conducts holes
- polyatomic molecule
- molecule formed of more than one atom
- repulsion constant
- experimental parameter associated with a repulsive force between ions brought so close together that the exclusion principle is important
- reverse bias configuration
- diode configuration that results in low current
- rotational energy level
- energy level associated with the rotational energy of a molecule
- selection rule
- rule that limits the possible transitions from one quantum state to another
- semiconductor
- solid with a relatively small energy gap between the lowest completely filled band and the next available unfilled band
- simple cubic
- basic crystal structure in which each ion is located at the nodes of a three-dimensional grid
- type I superconductor
- superconducting element, such as aluminum or mercury
- type II superconductor
- superconducting compound or alloy, such as a transition metal or an actinide series element
- valence band
- highest energy band that is filled in the energy structure of a crystal
- van der Waals bond
- bond formed by the attraction of two electrically polarized molecules
- vibrational energy level
- energy level associated with the vibrational energy of a molecule