Semiconductor Physics Vocabulary

Vocabulary flashcards covering intrinsic and extrinsic semiconductors, carrier concentrations, mobility, drift velocity, and current density equations based on lecture notes.

Intrinsic Semiconductor

A pure semiconductor where the number of holes and free electrons are equal ($n = p$).

Extrinsic Semiconductor

An impure semiconductor formed by doping, classified into P-type and N-type semiconductors.

P-type Semiconductor

An extrinsic semiconductor doped with trivalent elements (such as Boron or Al), where holes are majority carriers and electrons ($e^-$) are minority carriers.

N-type Semiconductor

An extrinsic semiconductor doped with pentavalent elements (such as Phosphorus, Ph, or Sb), where electrons ($e^-$) are majority carriers and holes are minority carriers.

Doping

The addition of impurities to a semiconductor to increase its conductivity.

Extrinsic Semiconductor Conductivity Formula

The formula $\sigma = q (n \mu_n + p \mu_p)$, where $\sigma$ is conductivity, $q$ is electron charge, $n$ is electron concentration, $\mu_n$ is electron mobility, $p$ is hole concentration, and $\mu_p$ is hole mobility.

Electron Concentration ($n$)

The concentration of electrons present in a semiconductor.

Hole Concentration ($p$)

The concentration of holes present in a semiconductor.

Electron Mobility ($\mu_n$)

The mobility corresponding to electrons in a semiconductor material.

Hole Mobility ($\mu_p$)

The mobility corresponding to holes in a semiconductor material.

Intrinsic Semiconductor Temperature Characteristic

Conductivity of a pure semiconductor is low at room temperature, zero at $0\,\text{K}$ (Zero Kelvin), and increases as temperature increases.

Drift Velocity ($v_d$)

The velocity of charge carriers in the direction opposite to an applied electric field $E$, with magnitude $v_d = \mu E$ proportional to the constant electric field.

Mobility ($\mu$)

The proportionality constant relating drift velocity $v_d$ to electric field $E$ in $v_d = \mu E$.

Current Density ($J$)

The total electric current per unit area, defined as $J = n q v_d = n q \mu E = \sigma E$, where $\sigma = n q \mu$.

Conduction Electrons

Electrons in the valence band that acquire thermal energy greater than the bandgap energy, moving into the conduction band where they become free charge carriers.

Electron Current Density ($J_n$)

The current density due to the motion of electrons, expressed as $J_n = n \mu_n q E = \sigma_n E$.

Hole Current Density ($J_p$)

The current density due to the motion of holes, expressed as $J_p = p \mu_p q E = \sigma_p E$.

Total Current Density Formula

The combined current density $J = J_n + J_p = (\sigma_n + \sigma_p) E = q (n \mu_n + p \mu_p) E = \sigma E$.

Intrinsic Current Density Formula

For an intrinsic semiconductor where $n = p = n_i$, total current density is $J = n_i (\mu_n + \mu_p) q E$.

Recombination

The process where an electron and a hole meet and disappear, balancing the continuous generation of new electron-hole pairs by thermal energy.

Carrier Motion in Electric Field

Negative electrons and positive holes move in opposite directions under an applied electric field $E$, but because they carry opposite charges, their resulting currents flow in the same direction.