ECE 3610 1-4

allowed energy band

A band or range of energy levels that an electron in a crystal is allowed to occupy based on quantum mechanics.

density of states function

n The density of available quantum states as a function of energy, given in units of number per unit energy per unit volume.

electron effective mass

The parameter that relates the acceleration of an electron in the conduction band of a crystal to an external force; a parameter that takes into account the effect of internal forces in the crystal.

Fermi–Dirac probability function

The function describing the statistical distribution of electrons among available energy states and the probability that an allowed energy state is occupied by an electron.

fermi energy

In the simplest definition, the energy below which all states are filled with electrons and above which all states are empty at T= 0 K.

forbidden energy band

A band or range of energy levels that an electron in a crystal is not allowed to occupy based on quantum mechanics.

hole

The positively charged “particle” associated with an empty state in the top of the valence band.

hole effective mass

The parameter that relates the acceleration of a hole in the valence band of a crystal to an applied external force (a positive quantity); a parameter that takes into account the effect of internal forces in a crystal

k -space diagram

The plot of electron energy in a crystal versus k , where k is the momentum-related constant of the motion that incorporates the crystal interaction.

Kronig–Penney model

The mathematical model of a periodic potential function representing a one-dimensional single-crystal lattice by a series of periodic step functions.

Maxwell–Boltzmann approximation

The condition in which the energy is several kT above the Fermi energy or several kT below the Fermi energy so that the Fermi–Dirac probability function can be approximated by a simple exponential function.

acceptor atoms

Impurity atoms added to a semiconductor to create a p-type material

charge carrier

The electron and/or hole that moves inside the semiconductor and gives rise to electrical currents.

compensated semiconductor

r A semiconductor that contains both donors and acceptors in the same semiconductor region.

complete ionization

The condition when all donor atoms are positively charged by giving up their donor electrons and all acceptor atoms are negatively charged by accepting electrons.

degenerate semiconductor

A semiconductor whose electron concentration or hole concentration is greater than the effective density of states, so that the Fermi level is in the conduction band (n type) or in the valence band (p type).

donor atoms

Impurity atoms added to a semiconductor to create an n-type material

effective density of states

The parameter Nc, which results from integrating the density of quantum states gc (E ) times the Fermi function fF (E ) over the conduction-band energy, and the parameter Nv, which results from integrating the density of quantum states gv (E ) times [1 fF (E)] over the valence-band energy.

extrinsic semiconductor

A semiconductor in which controlled amounts of donors and/or acceptors have been added so that the electron and hole concentrations change from the intrinsic carrier concentration and a preponderance of either electrons (n type) or holes (p type) is created.

freeze-out

The condition that occurs in a semiconductor when the temperature is lowered and the donors and acceptors become neutrally charged. The electron and hole concentrations become very small.

binary semiconductor

A two-element compound semiconductor, such as gallium arsenide (GaAs).

covalent bonding

The bonding between atoms in which valence electrons are shared.

diamond lattice

The atomic crystal structure of silicon, for example, in which each atom has four nearest neighbors in a tetrahedral configuration.

doping

The process of adding specific types of atoms to a semiconductor to favorably alter the electrical characteristics.

elemental semiconductor

A semiconductor composed of a single species of atom, such as silicon or germanium.

epitaxial layer

A thin, single-crystal layer of material formed on the surface of a substrate.

ion implantation

One particular process of doping a semiconductor

lattice

The periodic arrangement of atoms in a crystal.

Miller indices

The set of integers used to describe a crystal plane.

primitive cell

The smallest unit cell that can be repeated to form a lattice

substrate

A semiconductor wafer or other material used as the starting material for further semiconductor processing, such as epitaxial growth or diffusion.

unit cell

A small volume of a crystal that can be used to reproduce the entire crystal

zincblende lattice

A lattice structure identical to the diamond lattice except that there are two types of atoms instead of one.