University Physics Volume 3

# Key Terms

### 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 $T=0KT=0K$
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
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
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