Diodes and Applications

Vocabulary-style flashcards covering semiconductor physics, diode characteristics, rectifiers, power supplies, and special-purpose diodes based on Chapter 16.

Silicon

A semiconductive material with 14 protons in its nucleus and four valence electrons in its outer shell.

Germanium

A semiconductive material with 32 protons in its nucleus and four valence electrons in the fourth shell.

Intrinsic semiconductor

A pure semiconductive material that has no impurities.

Covalent bonds

Bonds created by the sharing of valence electrons between atoms in a crystal structure.

Crystal

A solid material formed by atoms arranging themselves in a fixed pattern.

Hole

A vacancy left in the valence band when an electron jumps to the conduction band.

Electron-hole pair

The combination of a free electron in the conduction band and the vacancy it leaves behind in the valence band.

Recombination

The process that occurs when a conduction-band electron loses energy and falls back into a hole in the valence band.

Electron current

The movement of thermally generated free electrons in the conduction band toward the positive end of a semiconductor.

Hole current

Current produced at the valence level as valence electrons move into nearby holes, effectively moving the holes in the opposite direction.

Doping

The process of adding impurities to an intrinsic semiconductive material to increase and control the number of current carriers.

N-type semiconductor

A semiconductor material created by adding pentavalent impurity atoms, which provide extra conduction electrons.

P-type semiconductor

A semiconductor material created by adding trivalent impurity atoms, which provide extra holes.

Majority carrier

The most numerous charge carrier in a doped semiconductive material; for n-type it is electrons and for p-type it is holes.

Minority carrier

The least numerous charge carrier in a doped semiconductive material; for n-type it is holes and for p-type it is free electrons.

PN junction

The boundary formed between the p-type and n-type portions of a semiconductor material.

Diode

A semiconductive device made with a single pn junction that allows current in only one direction.

Bias

The use of a dc voltage to establish certain operating conditions for an electronic device.

Forward bias

The condition that permits majority carrier current through a pn junction by applying an external voltage.

Reverse bias

The condition that prevents current through the diode and widens the depletion region.

Depletion region

The area on both sides of the pn junction that is essentially depleted of any conduction electrons or holes.

Barrier potential ($V_B$)

The amount of voltage required to move electrons through the depletion region, approximately $0.7\,V$ for silicon and $0.3\,V$ for germanium at $25\,^{\circ}\text{C}$.

Reverse breakdown

A condition occurring when a large enough external reverse-bias voltage is applied, resulting in a rapid buildup of reverse current.

Avalanche effect

The rapid multiplication of conduction-band electrons in a reverse-biased diode due to collisions within the crystal.

V-I characteristic curve

A graph plotting the diode voltage versus the resulting current through the device.

Anode (A)

The term used for the p region terminal of a diode.

Cathode (K)

The term used for the n region terminal of a diode.

Rectifier

Electronic circuit that converts ac voltage into pulsating dc voltage.

Half-wave rectifier

A circuit that allows current through the load for only one half-cycle of the input voltage.

Average value ($V_{AVG}$)

The dc value of a rectified voltage measured on a dc voltmeter, calculated as $\frac{V_{p(out)}}{\pi}$ for half-wave.

PIV (Peak Inverse Voltage)

The maximum value of reverse voltage which occurs at the peak of the input cycle when the diode is reverse-biased.

Full-wave rectifier

A circuit that allows unidirectional current to travel to the load during the entire input cycle.

Bridge rectifier

A type of full-wave rectifier that uses four diodes to allow conduction during both half-cycles of the input.

Ripple voltage

The variation in output voltage from a power supply filter due to the charging and discharging of the filter capacitor.

Ripple factor ($r$)

The ratio of the ripple voltage ($V_r$) to the dc value of the filter output voltage ($V_{DC}$).

Regulator

An electronic circuit that maintains a constant dc voltage for variations in line voltage or load.

Line regulation

A measure of how much change occurs in the output voltage for a given change in the input voltage, expressed as a percentage.

Load regulation

A measure of how much change occurs in the output voltage over a certain range of load current values.

Zener diode

A silicon pn junction device designed for operation specifically in the reverse breakdown region.

Zener impedance ($Z_Z$)

The ratio of the change in zener voltage to the change in zener current, expressed as $Z_Z = \frac{\Delta V_Z}{\Delta I_Z}$.

Varactor

A type of diode that makes use of the depletion-region capacitance and acts as a voltage-variable capacitor.

LED (Light-Emitting Diode)

A type of semiconductor diode that emits visible or infrared light when it is forward-biased.

PV cell

A specialized diode, also known as a solar cell, that converts light energy directly into dc electricity.

Photodiode

A pn junction device that operates in reverse bias and uses light intensity to control the amount of reverse current.

Dark current

The negligible reverse current that exists in a photodiode when there is no incident light.