Electronics: Module Two - Diodes (PN Junction) Devices

Comprehensive vocabulary flashcards covering the properties, physics, equations, classifications, and applications of PN junction devices, LEDs, photodiodes, and Zener diodes.

Diode

A two terminal (anode and cathode) PN junction semiconductor that allows a unidirectional flow of current, enabling it to exhibit a rectifying property.

Forward voltage drop

The small amount of energy that needs to be applied across a diode's terminals for it to conduct current; for silicon, this is approximately $0.7\,V$.

Peak Inverse Voltage (PIV)

The maximum reverse voltage that a diode can withstand in the reverse direction without breaking down, failing, or avalanching.

Depletion region/layer

An area in a PN junction that has no mobile charge carriers and creates a potential barrier that opposes the movement of charges across the junction.

Barrier potential

The potential energy a charged particle must have to cross a PN junction, or the energy required for a particle to move from one region to another.

Diffusion

The process where charge particles redistribute themselves by moving from regions of high concentration to regions of low concentration using only thermal motion with no external force applied.

Diffusion current ($I_S$)

Current flow resulting from minority carriers (electrons in the p-side and holes in the n-side) migrating across the junction from the n-side to the p-side.

Drift current ($I_D$)

Current resulting from the movement of majority carriers across the junction influenced by the application of an electric field.

Shockley equation

The mathematical relationship between carrier density (diode current) and applied voltage: $I_D = I_0 \left[ \exp\left( \frac{q V_D}{n K T} \right) - 1 \right]$.

Thermal Voltage ($V_T$)

Defined as $V_T = \frac{KT}{q}$, which is approximately $25.9\,mV$ at room temperature.

Avalanche Breakdown

A breakdown effect occurring at reverse-bias voltages above $5\,V$ where minority carriers acquire high kinetic energy, collide with crystal ions, and disrupt covalent bonds to create more mobile carriers.

Zener Breakdown

A breakdown effect occurring at reverse-bias voltages below $5\,V$ where a strong electric field across the junction tears electrons out of their covalent bonds.

Knee (Cut-in) Voltage

The forward voltage level at which the current through the PN junction starts to increase rapidly along an exponential path.

Rectification

The process of converting an Alternating Current (AC) source into a Direct Current (DC) form, or specifically, into a pulsating DC.

Half Wave Rectifier

A circuit containing a single PN junction diode connected in series with a load resistor that allows only the positive half-cycles of an AC input signal to pass.

Full Wave Rectifier

A rectifying circuit (either center-tapped or bridge configuration) that rectifies both the positive and negative half-cycles of an input AC waveform.

Full Wave Bridge Rectifier

A rectifier arrangement using four individual diodes in a closed-loop configuration that does not require a center-tapped transformer.

Ripple

The cyclic change or variation in the level of the output voltage of a rectifier caused by residual AC components in the DC output.

Filter

A device, typically a capacitor placed across a load resistor, used to smoothen out pulsations and remove unwanted frequencies from a rectifier output.

Diode Clipper (Limiter)

A circuit used to eliminate part of a waveform that is above or below a certain reference level without distorting the remaining part of the applied signal.

Diode Clamper (Level Shifter)

A network containing a capacitor, a diode, and a resistive element used for shifting the entire waveform of an AC signal up or down by adding a DC voltage.

Light Emitting Diode (LED)

An optical semiconductor device that converts electrical energy directly into light energy when forward biased through the recombination of electrons and holes.

Photodiode

A semiconductor component, often with a PIN structure, that converts light energy into electric current by generating electron-hole pairs in the depletion region.

Zener Diode

A type of diode designed to operate in the reverse breakdown region to maintain a fixed voltage level despite variations in source voltage or load current.

Diode

A two terminal (anode and cathode) PN junction semiconductor that allows a unidirectional flow of current, enabling it to exhibit a rectifying property.

Forward voltage drop

The small amount of energy that needs to be applied across a diode's terminals for it to conduct current; for silicon, this is approximately $0.7\,V$.

Peak Inverse Voltage (PIV)

The maximum reverse voltage that a diode can withstand in the reverse direction without breaking down, failing, or avalanching.

Depletion region/layer

An area in a PN junction that has no mobile charge carriers and creates a potential barrier that opposes the movement of charges across the junction.

Barrier potential

The potential energy a charged particle must have to cross a PN junction, or the energy required for a particle to move from one region to another.

Diffusion

The process where charge particles redistribute themselves by moving from regions of high concentration to regions of low concentration using only thermal motion with no external force applied.

Diffusion current ($I_S$)

Current flow resulting from minority carriers (electrons in the p-side and holes in the n-side) migrating across the junction from the n-side to the p-side.

Drift current ($I_D$)

Current resulting from the movement of majority carriers across the junction influenced by the application of an electric field.

Shockley equation

The mathematical relationship between carrier density (diode current) and applied voltage: $I_D = I_0 \left[ \exp\left( \frac{q V_D}{n K T} \right) - 1 \right]$.

Thermal Voltage ($V_T$)

Defined as $V_T = \frac{KT}{q}$, which is approximately $25.9\,mV$ at room temperature.

Avalanche Breakdown

A breakdown effect occurring at reverse-bias voltages above $5\,V$ where minority carriers acquire high kinetic energy, collide with crystal ions, and disrupt covalent bonds to create more mobile carriers.

Zener Breakdown

A breakdown effect occurring at reverse-bias voltages below $5\,V$ where a strong electric field across the junction tears electrons out of their covalent bonds.

Knee (Cut-in) Voltage

The forward voltage level at which the current through the PN junction starts to increase rapidly along an exponential path.

Rectification

The process of converting an Alternating Current (AC) source into a Direct Current (DC) form, or specifically, into a pulsating DC.

Half Wave Rectifier

A circuit containing a single PN junction diode connected in series with a load resistor that allows only the positive half-cycles of an AC input signal to pass.

Full Wave Rectifier

A rectifying circuit (either center-tapped or bridge configuration) that rectifies both the positive and negative half-cycles of an input AC waveform.

Full Wave Bridge Rectifier

A rectifier arrangement using four individual diodes in a closed-loop configuration that does not require a center-tapped transformer.

Ripple

The cyclic change or variation in the level of the output voltage of a rectifier caused by residual AC components in the DC output.

Filter

A device, typically a capacitor placed across a load resistor, used to smoothen out pulsations and remove unwanted frequencies from a rectifier output.

Diode Clipper (Limiter)

A circuit used to eliminate part of a waveform that is above or below a certain reference level without distorting the remaining part of the applied signal.

Diode Clamper (Level Shifter)

A network containing a capacitor, a diode, and a resistive element used for shifting the entire waveform of an AC signal up or down by adding a DC voltage.

Light Emitting Diode (LED)

An optical semiconductor device that converts electrical energy directly into light energy when forward biased through the recombination of electrons and holes.

Photodiode

A semiconductor component, often with a PIN structure, that converts light energy into electric current by generating electron-hole pairs in the depletion region.

Zener Diode

A type of diode designed to operate in the reverse breakdown region to maintain a fixed voltage level despite variations in source voltage or load current.