Electronics Exam: Terms and Symbols

Vocabulary study cards covering electronic symbols, fundamental semiconductor terminology, and pn-junction operation.

$$n$$

Free-electron concentration in a semiconductor; per cubic centimeter.

$$p$$

Hole concentration in a semiconductor; per cubic centimeter.

$$n_i$$

Intrinsic carrier concentration.

$$N_D$$

Donor-atom doping concentration.

$$N_A$$

Acceptor-atom doping concentration.

$$n_n$$

Electron concentration in the n-type region; majority carriers.

$$p_p$$

Hole concentration in the p-type region; majority carriers.

$$n_{p0}$$

Equilibrium minority-electron concentration in the p-type region.

$$p_{n0}$$

Equilibrium minority-hole concentration in the n-type region.

Subscript $0$

Equilibrium value, before any external voltage is applied.

$$q$$

Magnitude of the elementary electric charge; in coulombs.

$$T$$

Absolute temperature; in kelvins.

$$k$$

Boltzmann constant.

$$B$$

Material-dependent constant for intrinsic carrier concentration.

$$E_g$$

Energy bandgap of the semiconductor; in electronvolts.

$$V_T$$

Thermal voltage.

$$E$$

Electric-field strength in the semiconductor.

$$\mu_n$$

Electron mobility.

$$\mu_p$$

Hole mobility.

$$D_n$$

Electron diffusion coefficient.

$$D_p$$

Hole diffusion coefficient.

$$J$$

Electric current density; current per unit area.

$$I$$

Electric current; in amperes.

$$A$$

Cross-sectional area through which current flows.

$$v_{\text{drift}}$$

Drift velocity of a charge carrier.

$$\sigma$$

Electrical conductivity.

$$\rho$$

Electrical resistivity.

$$L$$

Length of a conducting sample along current flow.

$$R$$

Electrical resistance.

$$V_0$$

Built-in potential barrier across the pn-junction depletion region.

$$V_F$$

Magnitude of the applied forward-bias voltage.

$$V_R$$

Magnitude of the applied reverse-bias voltage.

$$V_{BR}$$

Magnitude of the junction reverse-breakdown voltage.

$$V_Z$$

Zener breakdown or regulation voltage.

$V$ (junction)

Applied voltage across the junction terminals.

$$W$$

Total width of the depletion region.

$$x_n$$

Depletion-region width extending into the n-type side.

$$x_p$$

Depletion-region width extending into the p-type side.

$$\epsilon_s$$

Electrical permittivity of the semiconductor.

$$Q_J$$

Magnitude of the fixed charge on either side of the depletion region.

$$Q_+$$

Positive ionized-donor charge on the n side of the depletion region.

$$Q_-$$

Negative ionized-acceptor charge on the p side of the depletion region.

$I_D$ (Chapter 3)

Majority-carrier diffusion current across the pn junction, p side to n side.

$$I_S$$

Junction scale current; also reverse-saturation and minority-carrier drift current.

$$L_p$$

Diffusion length of minority holes in the n-type region.

$$L_n$$

Diffusion length of minority electrons in the p-type region.

$$p_n(x)$$

Hole concentration at a given position within the n-type region.

$$n_p(x)$$

Electron concentration at a given position within the p-type region.

$$x$$

Position or distance along the semiconductor.

$$\frac{dp}{dx}$$

Hole-concentration gradient with distance.

$$\frac{dn}{dx}$$

Electron-concentration gradient with distance.

$$J_{p,\text{diff}}$$

Hole diffusion-current density.

$$J_{n,\text{diff}}$$

Electron diffusion-current density.

$$J_{\text{drift}}$$

Total drift-current density.

$$J_{p,\text{drift}}$$

Hole drift-current density.

$$J_{n,\text{drift}}$$

Electron drift-current density.

Intrinsic semiconductor

Pure, undoped semiconductor with equal electron and hole concentrations.

Extrinsic semiconductor

Semiconductor whose carrier concentration is altered by adding dopants.

Doping

Adding impurity atoms to control a semiconductor's carrier concentrations.

Donor impurity

Dopant that provides an additional free electron to silicon.

Acceptor impurity

Dopant that creates a hole by accepting an electron.

Phosphorus

A typical donor dopant used to make n-type silicon.

Boron

A typical acceptor dopant used to make p-type silicon.

N-type semiconductor

Donor-doped semiconductor with electrons as majority carriers.

P-type semiconductor

Acceptor-doped semiconductor with holes as majority carriers.

Majority carriers

Charge carriers more abundant in a doped region.

Minority carriers

Charge carriers less abundant in a doped region.

Majority carriers in n-type silicon

Electrons.

Minority carriers in n-type silicon

Holes.

Majority carriers in p-type silicon

Holes.

Minority carriers in p-type silicon

Electrons.

Electron-hole pair

A free electron and the hole left by its liberation from a covalent bond.

Thermal generation

Creation of mobile electrons and holes by thermal energy.

Recombination

A mobile electron fills a hole, removing both free carriers.

Mass-action law

At equilibrium, electron and hole concentrations have a fixed product.

Drift

Motion of charge carriers caused by an electric field.

Diffusion

Motion of carriers from higher to lower concentration.

Drift current

Current due to carrier motion in an electric field.

Diffusion current

Current due to nonuniform carrier concentration.

Electric field

Force per unit charge; drives carrier drift.

Electron drift direction

Opposite the electric-field direction.

Hole drift direction

Same as the electric-field direction.

Conventional current

Direction of positive charge flow; opposite electron motion.

Mobility

Carrier drift response to an electric field.

Diffusion coefficient

Material parameter describing carrier diffusion.

Concentration gradient

How rapidly carrier concentration changes with position.

Current density

Amount of current flowing per unit cross-sectional area.

Conductivity

A material's ability to conduct electric current.

Resistivity

A material's opposition to electric-current flow.

Einstein relation

Relationship between carrier diffusion coefficients, mobilities, and thermal voltage.

PN junction

Boundary within one crystal between p-type and n-type regions.

Anode

The diode terminal connected to its p-type region.

Cathode

The diode terminal connected to its n-type region.

Depletion region

Junction region with very few mobile majority carriers.

Space-charge region

Another name for the depletion region containing uncovered dopant ions.

Ionized donor

Immobile positive dopant ion left after a donor supplies an electron.

Ionized acceptor

Immobile negative dopant ion formed after an acceptor takes an electron.

Depletion electric field direction

From positive ionized donors on the n side toward the p side.

Built-in barrier

Internal potential across the depletion region that opposes majority-carrier diffusion.

Built-in voltage at external open terminals

Internal barrier exists, but measured terminal voltage is zero.