Hall Effect Part 2

Majority Carrier

The charge carrier present in the greatest concentration inside a semiconductor. Examples: Electrons in n-type material; holes in p-type material.

Minority Carrier

The charge carrier present in the lowest concentration inside a semiconductor.

Carrier Concentration

The number of mobile charge carriers per unit volume.

Carrier Lifetime

The average time an electron or hole exists before recombination.

Thermal Excitation

The process by which heat supplies enough energy for electrons to move into the conduction band.

Recombination

The process where an electron fills a hole, removing both carriers.

Generation

The creation of an electron-hole pair.

Electron-Hole Pair (EHP)

A free electron and corresponding hole created simultaneously when sufficient energy is supplied.

Fermi–Dirac Distribution

A function describing the probability that an electron state is occupied at a given energy.

Donor Atom

An impurity atom that contributes an extra electron to the semiconductor. Example: Phosphorus in silicon.

Acceptor Atom

An impurity atom that creates a hole in the semiconductor. Example: Boron in silicon.

Donor Level

An energy level introduced slightly below the conduction band by donor impurities.

Acceptor Level

An energy level introduced slightly above the valence band by acceptor impurities.

n-Type Semiconductor

A semiconductor whose majority carriers are electrons.

p-Type Semiconductor

A semiconductor whose majority carriers are holes.

Degenerate Semiconductor

A heavily doped semiconductor whose Fermi level enters a conduction or valence band.

Carrier Freeze-Out

A low-temperature condition where dopant atoms are not fully ionized.

Direct Band Gap Semiconductor

A semiconductor whose conduction-band minimum and valence-band maximum occur at the same momentum. Efficient for LEDs and lasers. Examples: GaAs; GaN.

Indirect Band Gap Semiconductor

A semiconductor whose conduction-band minimum and valence-band maximum occur at different momenta. Examples: Silicon; Germanium.

Radiative Recombination

Recombination that releases energy as a photon.

Non-Radiative Recombination

Recombination that releases energy as heat instead of light.

Carrier Mobility

The ease with which electrons or holes move through a material under an electric field.

Saturation Velocity

The maximum average velocity charge carriers reach in a strong electric field.

Hall Coefficient

A quantity relating Hall voltage to magnetic field and current. Symbol: RH.

Hall Mobility

The carrier mobility calculated from Hall-effect measurements.

Hall Angle

The angle between the direction of current flow and the net carrier motion.

Hall Electric Field

The electric field generated by charge separation inside a Hall-effect system.

Hall Measurement

A technique used to determine carrier type, carrier concentration, and mobility.

Two-Carrier Conduction

A conduction mechanism where both electrons and holes contribute significantly to current flow.

Charge Compensation

A condition where donor and acceptor impurities partially cancel each other's effects.

Corbino Disk

A conducting disk with concentric circular electrodes.

Corbino Geometry

An experimental arrangement that removes Hall-voltage buildup.

Radial Current

Current flowing between the center and edge of a Corbino disk.

Azimuthal Current

Current flowing around the circumference of a Corbino disk.

Corbino Effect

The generation of circular currents in a conducting disk placed in a magnetic field.

Corbino Magnetoresistance

Magnetoresistance measured using a Corbino disk.

Geometric Magnetoresistance

Magnetoresistance produced primarily by the geometry of a device.

Magnetoresistance

The change in electrical resistance caused by a magnetic field.

Positive Magnetoresistance

Resistance increases as magnetic field strength increases.

Negative Magnetoresistance

Resistance decreases as magnetic field strength increases.

Ordinary Magnetoresistance

Magnetoresistance caused by Lorentz-force deflection of charge carriers.

Magnetoresistive Ratio

The fractional change in resistance due to an applied magnetic field.

Giant Magnetoresistance (GMR)

A large resistance change occurring in layered magnetic materials. Discovered in 1988.

Tunnel Magnetoresistance (TMR)

Magnetoresistance arising from electron tunneling through an insulating barrier.

Colossal Magnetoresistance (CMR)

An extremely large magnetoresistance observed in certain manganese oxide materials.

Magnetic Read Head

A sensor that uses magnetoresistance to read data from magnetic storage devices.

Hall Parameter

The ratio of gyrofrequency to collision frequency.

Gyrofrequency

The frequency at which a charged particle circles magnetic field lines.

Larmor Radius

The radius of the circular path followed by a charged particle in a magnetic field.

Magnetized Plasma

A plasma whose charged particles are strongly influenced by magnetic fields.

Hall Current in Plasma

A current caused by the different magnetic responses of electrons and ions.

E × B Drift

The drift motion of charged particles caused by crossed electric and magnetic fields.

Plasma Conductivity Tensor

A mathematical description of conductivity in different directions within a magnetized plasma.

Hall-Effect Thruster

An electric propulsion device that accelerates ions using crossed electric and magnetic fields.

Xenon Propellant

The most common propellant used in Hall thrusters.

Ionization Chamber

The region where neutral xenon atoms become ionized.

Acceleration Channel

The region where ions are accelerated and expelled.

Magnetic Confinement

The use of magnetic fields to trap electrons.

Electron Trap

A magnetic configuration that restricts electron motion while allowing ions to escape.

Neutralizer Cathode

A cathode that injects electrons into the exhaust plume to maintain charge neutrality.

Specific Impulse (Isp)

A measure of propulsion efficiency. Units: seconds.

Ion Beam

A stream of accelerated ions leaving the thruster.

Exhaust Velocity

The speed at which propellant leaves the thruster.

Anomalous Hall Effect (AHE)

A Hall voltage generated partly by the material's internal magnetization.

Intrinsic Anomalous Hall Effect

Anomalous Hall behavior originating from the electronic band structure itself.

Extrinsic Anomalous Hall Effect

Anomalous Hall behavior caused by scattering processes.

Skew Scattering

Asymmetric scattering of electrons that contributes to the anomalous Hall effect.

Side-Jump Mechanism

A small lateral displacement of charge carriers during scattering that contributes to the anomalous Hall effect.

Berry Curvature

A property of electronic band structures that acts like a magnetic field in momentum space.

Spin

An intrinsic quantum property of particles that behaves like angular momentum.

Spin-Up State

An electron spin orientation aligned with a chosen reference direction.

Spin-Down State

An electron spin orientation opposite to the chosen reference direction.

Spin Current

A flow of spin angular momentum.

Spin Hall Effect (SHE)

The generation of transverse spin currents from an ordinary electric current.

Inverse Spin Hall Effect (ISHE)

The conversion of a spin current into an electrical voltage.

Spin Accumulation

The buildup of excess spin-up or spin-down electrons at a material boundary.

Spin-Orbit Coupling

An interaction between an electron's spin and its orbital motion around the nucleus.

Spintronics

A field of electronics that exploits both charge and spin.