# What is the Hall Constant?

If a current-carrying conductor is located in a magnetic field, a force acts on the charge carriers perpendicular to the current and magnetic field direction. The **resulting charge separation is called Hall effect** and **results in a measurable Hall voltage**. This is **proportional to the Hall coefficient** and the magnetic field strength. The Hall coefficient and its sign in turn depend on the charge carrier density and the type of charge carriers.

In a doped semiconductor, either negatively charged electrons or positively charged “holes”, ie missing electrons, can be responsible for a current flow. In a conventional electrical conductor such as copper, however, only electrons flow.

The **Hall coefficient can be measured** if the magnetic flux density of the magnet used is known, by determining the **conductor thickness, the Hall voltage and the current intensity**.

The effect described above allows a non-contact and precise measurement of magnetic fields. However, using a permanent magnet with known magnetic flux density, a whole range of other parameters can be determined.

This is used for example in the **automotive industry**, where numerous sensors for example **for the measurement of speed, level or torque are used**. Thanks to contactless measurement, Hall effect sensors are hardly susceptible to external influences and therefore wear-resistant.

Even very strong magnetic fields, such as those used in magnetic resonance imaging (MRI) can be determined by means of the Hall effect.

## Measuring instruments for determining the Hall constant

### HCS 1/10/100

The HCS System permits the characterization of semiconductor devices, it measures: **mobility, resistivity, charge carrier concentration and Hall constant.**

### TFA

**Unique** device for a comprehensive **thin film** characterization from the **nm** to the **µm** scale. The TFA permits the characterization of semiconductor devices, it measures (among other parameters): **mobility, resistivity, charge carrier concentration and Hall constant.**