The phenomenon in which a transverse voltage (Hall voltage) is developed across a conductor or semiconductor when it carries current in the presence of a perpendicular magnetic field.
Table of Contents
Principle of Hall Effect
- Charge carriers (electrons or holes) experience a force called Lorentz force.
- This force pushes carriers to one side of the conductor.
- As a result, a potential difference is developed across the sides — called Hall voltage.
Mathematical Expression
The Hall voltage is given by:
\[
V_H = \frac{B I}{n q t}
\]
Where:
- \( V_H \) = Hall voltage
- \( B \) = Magnetic field (Tesla)
- \( I \) = Current (Ampere)
- \( n \) = Charge carrier concentration
- \( q \) = Charge of carrier
- \( t \) = Thickness of conductor
Hall Coefficient
The Hall coefficient (\( R_H \)) is defined as:
\[
R_H = \frac{E_H}{J B} = \frac{1}{n q}
\]
Where:
- \( E_H \) = Hall electric field
- \( J \) = Current density
Key Points:
- Positive \( R_H \) → Indicates p-type semiconductor
- Negative \( R_H \) → Indicates n-type semiconductor
Working of Hall Effect
- A conductor/semiconductor is connected to a DC supply → current flows.
- A magnetic field is applied perpendicular to current.
- Charge carriers deflect due to Lorentz force.
- Charges accumulate on one side → Hall voltage is generated.
Applications of Hall Effect
- Measurement of Magnetic Field
- Hall probes are used to measure flux density.
- Determination of Carrier Type
- Helps identify whether semiconductor is n-type or p-type.
- Measurement of Carrier Concentration
- Used in semiconductor analysis.
- Hall Effect Sensors
- Speed detection (motors)
- Position sensing
- Proximity sensors
- Current Measurement
- Non-contact current sensing devices.
Advantages
- Simple and reliable
- Works for both conductors and semiconductors
- Non-contact measurement possible
Limitations
- Hall voltage is very small → requires amplification
- Sensitive to temperature variations
- Accuracy affected by material properties