Semiconductors, Diodes, and Electronic Components: Key Concepts and Properties

Semiconductors

A special class of elements with a conductivity between that of a good conductor and that of an insulator.

Germanium (Ge), Silicon (Si), and Gallium Arsenide (GaAs)

The three most frequently used semiconductor materials in the construction of electronic devices, according to the document.

Conductors

Materials that allow the easy flow of electric current due to the presence of free electrons or charge carriers.

Insulators

Materials that resist the flow of electric current, having very few or no free charge carriers.

Material Resistance

The opposition that a material offers to the flow of electric current.

R=ρ(l/A), R= Resistance ρ = Resistivity l = length A = Area

The formula for the material resistance of a component.

Ionic bond

The type of bond that results from attractive forces between positive and negative ions.

Metallic bond

The type of bond that results from attractive forces between a group of positive ions and a sea of electrons that are free to move.

Covalent bond

The type of bond that results when atoms share their valence electrons with other atoms.

Intrinsic material

A semiconductor material that is free from impurities.

Doping

The process of adding impurities to a semiconductor material to alter its electrical properties.

Extrinsic material

A semiconductor material with some impurities added.

Donor impurities

Impurities added to a semiconductor that have five valence electrons.

n-type material

An extrinsic material formed by adding donor impurities.

Electrons

The charge carriers in an n-type material.

Acceptor impurities

Impurities added to a semiconductor that have three valence electrons.

p-type material

An extrinsic material formed by adding acceptor impurities.

Holes

The charge carriers in a p-type material.

Energy gap

The measure of the energy difference between the top of the valence band and the bottom of the conduction band in a semiconductor material. The wider this is, the harder the material can produce free electrons.

Diode

A two-terminal electronic component that conducts electric current in only one direction.

Anode

The terminal of a diode connected to the p-type material.

Cathode

The terminal of a diode connected to the n-type material.

Depletion region

The region near the p-n junction that is depleted of carriers due to diffusion across the junction.

Barrier potential

The amount of energy required to move electrons through the electric field, also known as built-in potential or contact potential.

0.7 V

The typical barrier potential for a Silicon (Si) diode.

0.3 V

The typical barrier potential for a Germanium (Ge) diode.

Biasing

The application of DC voltage to a diode to establish the desired operating condition.

Forward bias

The biasing condition where the p-type material is connected to the positive terminal and the n-type material is connected to the negative terminal.

Reverse bias

The biasing condition that prevents current through the p-n junction.

Avalanche effect

The phenomenon that occurs for large reverse voltages across the p-n junction, producing a large reverse current that can destroy the diode.

IV characteristic curve

graphical plot that shows the current-voltage relationship of a diode.

Forward conduction region

The region of the VI curve where a diode is forward-biased and conducting.

Reverse leakage region

: The region of the VI curve where a diode is reverse-biased and only a small leakage current flows.

Zener region

The specific region of the VI curve where the reverse voltage exceeds the breakdown voltage, causing a sudden increase in current.

Forward resistance

The resistance offered by a p-n junction diode when it is forward biased.

Reverse resistance

he resistance offered by a p-n junction diode when it is reverse biased.

Static or DC resistance

The total or large-signal resistance of a diode at a particular operating point, calculated as the ratio of voltage to current (V/I).

Dynamic or AC resistance

The small-signal resistance of a diode, calculated as the change in voltage divided by the change in current (ΔV/ΔI).

Bulk resistance

The sum of ohmic resistances within the diode.

Transition capacitance and diffusion capacitance

The two types of capacitance that can arise in semiconductor diodes.

Transition capacitance

A capacitance that occurs when the diode is reverse-biased, due to the charge stored in the depletion region.

C_T =ϵA/W

The formula for transition capacitance (C_T).

Diffusion capacitance

A capacitance that occurs in a forward-biased diode due to the charge stored in the minority carriers as they diffuse across the p-n junction.

C_D =dQ/dV

The formula for diffusion capacitance (C_D).

Forward Current (I_F)

A diode parameter that represents the magnitude of current a diode can handle without burning when forward-biased.

Forward Voltage (V_F)

A diode parameter that represents the required voltage to produce forward current.

Reverse Saturation Current (I_S)

A diode parameter that represents the magnitude of current that leaks when the diode is reversed-biased, often called the leakage current.

Reverse Breakdown Voltage (V_BR)

A diode parameter that represents the maximum reverse voltage that can be applied before current surges and enters the zener region, also called Peak Inverse Voltage (PIV) or Peak Reverse Voltage (PRV).

Maximum Power Dissipation (P_Dmax)

A diode parameter that represents the maximum power the diode can handle without burning.

Maximum Junction Temperature

A diode parameter that represents the maximum temperature the diode's junction can operate at before burning.

Reverse recovery time (T_rr)

The time it takes for a diode to switch from a forward-conduction state to a reverse-blocking state.

A digital display meter (DDM) (with a diode-checking function) and the ohmmeter section of a multimeter ;

The two most common methods for testing the condition of a diode.

Forward Bias = low R

When using an ohmmeter to test a diode, this type of bias would result in a low resistance reading.

Reverse Bias = high R

When using an ohmmeter to test a diode, this type of bias would result in a high resistance reading.