1.3 Magnetic Effects in Semiconductors

Galvanomagnetic effects are exploited in solid-state magnetic sensors. They are the result of the magnetic induction on mobile carriers through the Lorentz force

$$\mathbf{F} = q \cdot (\mathbf{v} \times \mathbf{B})$$ (1.2)

where $q$ is the electronic charge and $\mathbf{v}$ denotes the velocity of the carriers.

Four different effects arise when a magnetic induction is applied to a semiconductor device carrying a current: a Hall voltage, a carrier deflection, a magnetoconcentration, and a magnetoresistance. The last one gives a quadratic response to the magnetic induction whereas the others result in a linear response. A solid-state magnetic sensor is designed in such a way that one or several of those effects are maximized within the device body.

Galvanomagnetic effects are used as a classification of solid-state magnetic sensors. Hall devices exploit the Hall effect. Magnetotransistors use the magnetoconcentration and carrier deflection. MAGFETs use carrier deflection as the physical effect to detect a magnetic field. This is not a fully appropriate classification of the solid-state magnetic sensors, because it is not clear that only one of such galvanomagnetic effects would prevail over the others. Besides, the solid-state magnetic sensors must fulfill some other specifications depending on their application.