Electronics: Semiconductor Theory and Diodes

Vocabulary and key concepts focusing on semiconductor basics, diode models, and circuit applications based on the lecture notes.

Energy Gap ($E_g$)

A barrier that opposes the movement of valence electrons outside the system; it is proportional to the number of valence electrons.

Conductor

A material with low resistance and $1$-$3$ valence electrons that follows a Positive Temperature Coefficient ($PTC$).

Insulator

A material with high resistance and $5$-$8$ valence electrons that follows a Negative Temperature Coefficient ($NTC$).

Positive Temperature Coefficient ($PTC$)

The property where heating a material increases resistance due to atoms vibrating and causing more collisions.

Negative Temperature Coefficient ($NTC$)

The property where heating a material decreases resistance because thermal energy releases a flood of new free electrons and holes.

Intrinsic Semiconductor

A pure semiconductor without any significant dopant species present.

Extrinsic Semiconductor

A semiconductor material that has been subjected to the doping process.

Doping

The incorporation of impurities into a semiconductor to change its conductivity for device fabrication.

Interstitial Doping

A methods of doping where foreign atoms are squeezed between regular crystal sites.

Substitutional Doping

A method of doping where foreign atoms occupy the sites of host atoms.

Silicon ($Si$)

A semiconductor material that is thermally stable up to $200^\circ C$, has a threshold voltage of $0.7\,V$, and an energy gap of $1.1\,eV$.

Germanium ($Ge$)

A semiconductor material that is heat sensitive up to $100^\circ C$, has a threshold voltage of $0.3\,V$, and an energy gap of $0.67\,eV$.

Heterojunction

An interface formed between two dissimilar semiconductors, serving as a key component for high-speed and photonic devices.

Saturation Current ($I_s$) Temperature Rule

The saturation current doubles for every $10^\circ C$ rise in temperature.

Reverse Saturation Current Behavior

Carried by minority carriers generated by thermal energy, this current remains constant regardless of increases in external reverse voltage until breakdown occurs.

LED Operating Voltage Range

The typical forward voltage required for standard indicator LEDs to turn on, ranging from $1.7\,V$ to $3.3\,V$.

Schottky Diode

A diode formed by joining a doped semiconductor with a metal, characterized by faster switching times and a threshold voltage of $0.2\,V$ to $0.4\,V$.

Zener Diode

Also known as a breakdown diode or voltage regulator, it is designed to work in the reverse-bias avalanche breakdown region.

Varactor Diode

A diode for which the reverse bias can be changed to vary the internal capacitance.

Ideal Diode Model

The first approximation model where a diode acts as a simple switch (ON in forward bias, OFF in reverse bias).

Piecewise Linear Model

The third approximation model where the diode is represented by a switch, a voltage source ($V_{TH}$), and a resistor.

Simplified Diode Model

Also known as the practical or constant voltage drop model, it is the most frequently employed model in electronic system analysis.

Clipper

A network that employs diodes to remove a portion of an input signal without distorting the remaining part of the waveform.

Clamper

A network consisting of a diode, resistor, and capacitor that shifts a waveform to a different DC level without changing its appearance.

Half Wave Rectifier Efficiency

The efficiency rating for a half wave rectifier, which is approximately $40.6\%$.

Voltage Multiplier

A specialized rectifier circuit that produces a DC output that is an integer multiple of the AC peak input voltage.