Appendix:

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Comprehensive Glossary

Name

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Abrupt p-n junction

p-n junction with a step function doping profile

Acceptor

An atom which is likely to take on one or more electrons when placed in a crystal

Accumulation

Accumulation of free carriers in a semiconductor

Applied bias

Voltage applied to the structure

Avalanche breakdown

Breakdown mechanism caused by impact ionization leading to avalanching due to carrier multiplication

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Bandgap

The range of energies between existing energy bands where no energy levels exist

Blackbody radiation

Radiation from an object due to thermal energy

Body Effect

The variation of the threshold voltage of an FET due to a variation of the substrate or bulk voltage. See also Body Effect

Bohr model

Model for the hydrogen atom as proposed by Niels Bohr

Bohr radius

Radius of the electron orbit in a hydrogen atom corresponding to the lowest energy energy solution of the Bohr model

Breakdown field

Electric field at breakdown

Built-in potential

Potential across a structure in thermal equilibrium. The built-in potential equals the difference in work function of the two outer regions.

Built-in potential

Potential across a p-n diode in thermal equilibrium.

Bulk

Back contact of a MOSFET also referred to as the substrate contact.

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Capacitance

Charge per unit voltage

Channel implant

Ion implantation in the channel region used to adjust the threshold voltage of a MOSFET.

Channel length modulation

Variation of the channel due to an increase of the depletion region when increasing the drain voltage. A reduction of the channel yields a higher current.

CMOS

Complementary metal oxide silicon (transistor)

Compensation

The process of adding donors and acceptor to a crystal

Conduction band

Lowest empty or partially filled band in a semiconductor

Conductivity

The ratio of the current density to the applied electric field

Continuity equation

Equation which states that the rate of change of a density of particles equals the net flux of particles coming in

Crystal

A solid which consists of atoms placed in a periodic arrangment

Crystalline

Made of one or multiple crystals

C-V measurement

Capacitance versus voltage measurement

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de Broglie wavelength

Wavelength of a particle l = h/p

Debye length

Characteristic length over which the carrier density in a semiconductor changes by a factor e

Density of states

The density of electronic states per unit energy and per unit volume

Depletion

Removal of free carriers in a semiconductor

Depletion layer width

Width of the region close to the p-n junction without free carriers

Depletion mode FET

Transistor, which is normally on if the gate is connected to the source

Depletion region of a p-n diode

Region close to the p-n junction without free carriers

DIBL

Drain induced barrier lowering

Diffusion

Motion of particles caused by thermal energy

Diffusion length

Average distance minority carriers travel in a quasi-neutral region before they recombine

Donor

An atom which is likely to give off one or more electrons when placed in a crystal

Drain

Contact region of a MOSFET to which the electrons in the channel flow

DRAM

Dynamic random access memory

Drift

Motion of carriers caused by an electric field

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EAPROM

Electrically alterable programmable read only memory

Edge effects

EEPROM

Erasable electrically programmable read only memory

Electron

Particle with spin 1/2 and carrying a single negative charge (1.6 x 10-19 Coulomb)

Energy band

A collection of closely spaced energy levels

Energy level

The energy which an electron can have

Enhancement FET

Transistor, which is normally off if the gate is connected to the source.

Entropy

Heat divided by absolute temperature

Epitaxial layer

Thin layer of a single crystalline semiconductor grown on a substrate

EPROM

Electrically programmable read only memory

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FAMOS

Floating gate Avalanche injection Metal Oxide Silicon (transistor)

Fermi energy

The average energy per particle when adding particles to a distribution but without changing the entropy or the volume. Chemists refer to this quantity as being the electro-chemical potential

Fermions

Particles with half-integer spin

FET

Field Effect Transistor

Field implant

Doped region under the thick field oxide, which is obtained by ion implantation with the intend to eliminate the effect of the parasitic field oxide transistor.

Flash memory

Flat band

Bias conditions of an MOS capacitor for which the energy band diagram of the silicon is flat. The corresponding voltage is called the Flat band voltage

Flatband diagram

Energy band diagram of a M-S junction containing no net charge

Flatband diagram

Energy band diagram of a p-n diode containing no net charge

Flatband diagram

Energy band diagram of a MOS capacitor containing no net charge in the semiconductor

Forward bias

High current bias mode of a rectifying contact

Full-depletion approximation

A common approximation which simplifies the electrostatic analysis of semiconductor devices. Assumed is that the depletion region(s) is(are) fully depleted, with abrupt transitions to the adjacent quasi-neutral regions

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Gate

Electrode of an FET, which controls the charge in the channel

Gauss' law

One of Maxwell's equations, stating that the gradient of the electric field equals the charge density, divided by the dielectric constant.

Generation

Process by which electron-hole pairs are generated

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Heat

Thermal energy

High Injection

High injection occurs by definition when, while forward biasing a p-n diode, the minority carrier density equals or exceeds the doping concentration in the semiconductor. See also High-Current Analysis.

Hole

Particle associated with an empty electron level in an almost filled band

Hydrogen atom

An atom consisting of a proton and an electron

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Ideal diode analysis

p-n diode analysis based on recombination currents in the quasi-neutral regions

Ideal ohmic contact

Metal-semiconductor contact with zero resistance

Ideality factor

A number which characterizes the slope of a current-voltage plot as measured on a semi-logarithmic scale. A slope of a factor e per thermal voltage (or 1 decade/59 mV at room temperature) is considered ideal and is assigned an ideality factor of 1. A lower slope corresponds to a higher ideality factor.

Ideality factor

Impurity

A foreign atom in a crystal

Interface

Boundary between two materials

Intrinsic carrier density

The density of electrons and holes in an intrinsic semiconductor

Intrinsic semiconductor

A semiconductors free of defects or impurities

Inversion

Change of carrier type in a semiconductor obtained by applying an external voltage. In a MOSFET, inversion creates the free carriers, which cause the drain current.

Inversion layer

The layer of free carriers of opposite type at the semiconductor-oxide interface of a MOSFET

Ionization

The process of adding or removing an electron to/from an atom thereby creating a charged atom (i.e. ion)

I-V characteristics

Current-Voltage characteristics

I-V characteristics

I-V measurement

Current versus voltage measurement

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Laser diode

p-n diode with an optical cavity, which emits coherent light when forward biased

Latchup

High current state of a CMOS circuit caused by the parasitic bipolar transistors

LDD structure

Low doped drain transistor structure

Light emitting diode (LED)

p-n diode which emits light when forward biased

LOCOS

Local oxidation used to isolate two adjacent devices.

Long diode

p-n diode with a long quasi-neutral region as compared to the minority carrier diffusion length in that region

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Majority Carrier Density

The larger density of the two carrier types (electrons and holes). The majority carrier density is frequently - but not always - equal to the doping density.

Mass action law

The law which describes the relation between the densities of species involved in a chemical reaction

Minority Carrier Density

The lower density of the two carrier types (electrons and holes). The minority carrier density is typically orders of magnitude lower than the majority carrier density, yet plays an important role in p-n diodes and bipolar transistors.

Mobility

The ratio of the carrier velocity to the applied electric field

momentum

Mass times velocity

MOSFET

Metal-Oxide-Semiconductor Field Effect Transistor. See also MOSFET

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n+ semiconductor

n-type semiconductor with high donor density (< 1018 cm-3)

n- semiconductor

n-type semiconductor with low donor density (< 1016 cm-3)

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Ohmic contact

Metal-semiconductor contact with a linear current-voltage characteristic and low resistance

One-sided p-n junction

Junction with a very large doping density on one side and a very low density of the other side.

Output conductance

Ratio of output current variation to the output voltage variation

Overlap capacitance

Capacitance between the gate and the source/drain due to the overlap between the gate and the source/drain regions.

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p+ semiconductor

p-type semiconductor with high donor density (< 1018 cm-3)

p- semiconductor

p-type semiconductor with low donor density (< 1016 cm-3)

Particle-wave duality

Quantum mechanical concept, which states that particles can behave as waves and waves can behave as particles

Photodiode

A p-n junction which can be exposed to light, thereby yielding a photocurrent

Photoelectric effect

Emission of electrons from a metal when applying light with photon energy larger than the workfunction of the metal

Photon

Quantum of electromagnetic radiation

p-n junction

A junction between an n-type and a p-type semiconductor

Poisson's equation

Second order differential equation which relates the potential, f, to the charge density, r.

Poisson's equation

Poly-silicon

Poly-crystalline silicon. Sometimes referred to as poly.

PROM

Programmable read only memory

Punch through

Breakdown mechanism caused by the overlap between the source and drain depletion regions

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Quantum mechanics

Theory which describes particles by a wavefunction

Quasi-neutral region

Doped semiconductor region containing free carriers and being almost neutral

Quasi-neutral region

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RAM

Random access memory

Recombination

Process by which electron-hole pairs are removed

Recombination-generation current in a p-n diode

Current due to recombination of carriers in the depletion region of a p-n diode

Recombination-generation current in a p-n diode

Current due to band-to-band recombination of carriers in the depletion region of a p-n diode

Recombination-generation current in a p-n diode

see Shockley-Hall-Read

Recombination-generation current in a p-n diode

Current due to Shockley-Hall-Read recombination of carriers in the depletion region of a p-n diode

Rectifier

Device which converts an AC signal into a DC signal.

Resistivity

The ratio of the applied voltage to the current

Reverse bias

Low current bias mode of a rectifying contact

Reverse bias

Richardson constant

Material constant which affects the thermionic emission current in a metal-semiconductor junction

Richardson velocity

Average thermal velocity of carriers moving in a specific direction

ROM

Read only memory

Rydberg

Unit of atomic energy = 13.6 eV

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Saturation Velocity

Maximum velocity which can be obtained in a specific semiconductor

Schottky barrier

Barrier between a metal and semiconductor as seen by an electron or hole at the Fermi energy in the metal

Schottky barrier diode

Metal-semiconductor junction with a depletion region under the metal

Schottky barrier lowering

Lowering of the Schottky barrier height due to image forces (only used in current calculations)

Series resistance

Shell

Atomic states which are associated with one principle quantum number

Short channel effects

Deviations from the one-dimensional transistor model as observed in short channel transistors

Short diode

p-n diode with a short quasi-neutral region as compared to the minority carrier diffusion length in that region

Solar cell

A p-n diode, which converts optical power into electrical power

Source

Contact region of a MOSFET from which the electrons in the channel originate

State

A single solution to Schrödinger's equation defined by a unique set of quantum numbers

Strong Inversion

Strong inversion is obtained when the carrier density in an inversion layer equals or exceeds the carrier density in the substrate.

Substrate

The material in which a device is embedded or on to of which a device is fabricated

Subthreshold current

Transistor current when biased below threshold

Surface state

Midgap state caused by the termination of the lattice at the surface of a semiconductor

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Thermal energy

Energy associated with the temperature of an object

Thermal equilibrium

A system is in thermal equilibrium if every ongoing process is exactly balanced by its inverse.

Threshold Voltage

The gate-source voltage at which a transistor starts to conduct.

Transconductance

Ratio of output current variation to the input voltage variation

Transfer characteristic

Output voltage of a device plotted as a function of the input voltage

Transistor

Contraction of transresistance, a term used to describe a resistance which is controlled by a voltage at another node.

Tunnel contact

Ohmic contact in which carriers tunnel through a thin barrier layer

Tunneling

Quantum mechanical process by which a particle can pass through a barrier rather than having to go over the barrier

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Valence band

Highest filled or almost filled band in a semiconductor

Valence electrons

Electrons in the outer shell of an atom

Variable Depletion Layer Model

A MOSFET model which includes the variable depletion layer width between the inversion layer and the substrate

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Wave number

Number of zero crossings per unit length times p

Wave packet

Wave description of a localized particle

Well

Doped region of opposite doping type used in a CMOS process

Work

Mechanical energy

Work function

Potential an electron at the Fermi energy needs to gain to escape from a solid

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Zener breakdown

Breakdown mechanism caused by tunneling of carriers through the energy bandgap