SEMICONDUCTOR TERMS

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Some Terms used in the Semiconductor Technology

Acceptor Impurity

An impurity added to an intrinsic semiconductor that will accept an electron from a neighboring atom to create a hole.

Active Device

A device that has gain or controls another circuit.

Anode

The positive terminal of a device.

Avalanche breakdown

Reverse voltage breakdown that occurs when electrons gain sufficient energy that when they collide with other atoms they can free further electrons, and thereby creating more majority carriers.

Base

The region of a bipolar transistor situated between the collector and emitter. It originally gained its name because it formed the base material for the transistor.

Carrier

See current carrier

Cathode

The negative terminal of a device.

Channel

The region between the drain and source of a FET that carries the current flowing through the device.

Collector

One of the connections to a bipolar transistor.

Crystal lattice

The lattice or regular pattern in which atoms arrange themselves in a crystal.

Current carriers

The charged items, either electrons or holes that carry the current in a conductor or semiconductor. Both of them are mobile, and under the influence of a voltage they are caused to move, and this constitutes a current.

Depletion layer

The area in a p-n junction that is free of current carriers, i.e. it is depleted of carriers.

Diode

A two electrode device that has an asymmetrical V/I characteristic, and generally allows current to flow only in one direction.

Donor impurity

An impurity that gives or donates an extra electron into the crystal lattice.

Doping

The process where impurities are added to a semiconductor.

Drain

One of the electrodes connected to the channel in a field effect transistor

Electron

A negatively charged particle contained in an atom.

Emitter

One of the connections to a bipolar transistor.

Epitaxy

The growth of material onto a semiconductor. In this process the new material assumes the same crystal structure as the starting semiconductor.

Extrinsic semiconductor

A semiconductor whose electrical properties depend upon the presence of the impurities.

Gate

The control electrode in a field effect transistor.

Heterojunction

A p-n junction in a semiconductor between materials of different composition. Normal junctions are between p and n type versions of the same material.

Hole

The space left by an electron when it moves out of the orbit in an atom. It has a charge equal and opposite to that of an electron. In just the same way that electrons can move around a crystal lattice, holes can also move.

Impurities

The small traces of material added to a semiconductor. They have a valency of either one greater or less than that of the intrinsic material and in this way they add either holes or electrons to the lattice.

Intrinsic semiconductor

A pure semiconductor containing no impurity atoms.

Leakage current

The current that flows across a reverse biased p-n junction.

Majority carriers

The type of current carrier that predominates in a current flow.

Minority carriers

The type of current carrier that provides less than half the current flow.

Mobility

The ease with which the carriers flow. Holes are less mobile than electrons. The mobility is also dependent upon the type of material.

n-type semiconductor

Doped semiconductor in which the electrons outnumber the holes.

n+ semiconductor

Very heavily doped n-type semiconductor.

Photoresist

An emulsion that is applied to the semiconductor surface, and is sensitive to light. It is exposed to the pattern required for the next stage in the fabrication process. It is then washed and only the soluble areas are left to protect the semiconductor surface to the next stage of the process.

Planar transistor

A transistor or circuit that is fabricated by selective etching and diffusion.

p-type semiconductor

Doped semiconductor in which the holes outnumber the electrons.

p+ semiconductor

Very heavily doped p-type semiconductor.

Recombination

The process where a hole and electron combine.

Source

Th electrode at one end of the channel of a field effect transistor.

Substrate

The foundation or supporting base material on which an integrated circuit is fabricated.