Principle

The resistivity and Hall voltage of a rectangular germanium sample are measured as a function of temperature and magnetic field. The band spacing, the specific conductivity, the type of charge carrier and the mobility of the charge carriers are determined from the measurements.

Benefits

• Hall effect unit to control temperature, voltage, and supports intrinsic, p- and n-type Ge crystals
• Version with PC control and data acquisition
• Direct connection to PC via USB connection
• No extra interface necessary
• Magnetic field sensor can be connected directly with the Hall effect unit

Tasks

1. The Hall voltage is measured at room temperature and constant magnetic field as a function of the control current and plotted on a graph (measurement without compensation for defect voltage).
2. The voltage across the sample is measured at room temperature and constant control current as a function of the magnetic induction B.
3. The voltage across the sample is measured at constant control current as a function of the temperature. The band spacing of germanium is calculated from the measurements.
4. The Hall voltage U_H is measured as a function of the magnetic induction B, at room temperature. The sign of the charge carriers and the Hall constant R_H together with the Hall mobility μ_H and the carrier concentration p are calculated from the measurements.
5. The Hall voltage U_H is measured as a function of temperature at constant magnetic induction B and the values are plotted on a graph.

Learning objectives

• Semiconductor
• Band theory
• Forbidden zone
• Intrinsic conductivity
• Extrinsic conductivity
• Valence band
• Conduction band
• Lorentz force
• Magnetic resistance
• Mobility
• Conductivity
• Band spacing
• Hall coefficient

 Software included. Computer not provided.