ENGG212 Electronics - Module 2 Diodes Flashcards

Vocabulary-style flashcards covering the fundamental concepts, physics, classifications, and applications of PN junction diodes, LEDs, photodiodes, and Zener regulators based on ENGG212 lecture notes.

Diode

A two terminal (anode and cathode) PN junction semiconductor that allows only a unidirectional flow of current, exhibiting rectifying properties.

Forward biased condition

A state where the anode is made positive with respect to the cathode, allowing electricity to flow through the diode.

Reverse biased condition

A state where the anode is made negative with respect to the cathode, blocking the flow of electricity through the diode.

Forward voltage drop

A small amount of energy needed across diode terminals to conduct current, approximately $0.7\,V$ for silicon.

Peak Inverse Voltage (PIV)

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

Schottky diode

A semiconductor diode formed from the contact between a metal and a semiconductor rather than by a PN junction.

Depletion region/layer

An area near the PN junction that has no mobile charge carriers and opposes the flow of electrons from the n-side and holes from the p-side.

Potential barrier

The energy a charged particle must have to cross a PN junction and move from one region to another.

Diffusion current ($S_I$)

Current flow resulting from charge particles moving from regions of high concentration to regions of low concentration using only thermal motion with no external force.

Drift current ($D_I$)

Current flow influenced by the application of an electric field.

Shockley equation

An exponential relationship connecting diode current ($I_D$) and applied voltage ($V_D$), expressed as $I_D = I_0 [\exp(\frac{qV_D}{nKT}) - 1]$.

Thermal Voltage ($V_T$)

Defined as $\frac{KT}{q}$, with a value of approximately $25.9\,mV$ at room temperature.

Conduction voltage ($V_C$)

The minimum voltage value where noticeable currents are obtained, being $0.2\,V$ for Germanium and $0.7\,V$ for Silicon.

Avalanche Breakdown

A breakdown process where high kinetic energy minority carriers collide with crystal ions to disrupt covalent bonds, typically occurring at reverse-bias voltages above $5\,V$.

Zener Breakdown

A process where a strong electric field (about $2 \times 10^7\,V/m$) tears electrons from covalent bonds, typically occurring at reverse-bias voltages below $5\,V$.

Knee (Cut-in) Voltage

The forward voltage at which the current through the junction starts to increase rapidly.

Rectification

The process of converting an Alternating Current (AC) source into a Direct Current (DC) form using a rectifier.

Half wave rectifier

A circuit using a single PN junction diode in series with a load resistor that allows only the positive path of the AC signal to pass.

Ripple

A cyclic change or variation in the level of the output voltage due to AC components existing in the output DC voltage of a rectifier.

Diode clipper (limiter)

A circuit used to eliminate part of a waveform above or below a predetermined reference level without distorting the remaining part.

Diode clamper (level shifter)

A circuit that clamps a signal to a different DC level, shifting the entire AC waveform up or down.

Light Emitting Diode (LED)

An optical semiconductor device that converts electrical energy directly into light energy when forward biased.

Photodiode

A semiconductor device that accepts light energy as input and converts it into electric current, often utilizing a PIN structure.

Zener diode

A heavily doped diode that permits current in the forward direction and also in the reverse direction if the voltage exceeds the Zener voltage ($V_Z$).