Higher Physics Lab Soild State Physics



Exp-1 Measurement of resistivity of semiconductor by four probe method.
Exp-2 Determination of Energy Band Gap.

  • Built-in constant current source, dual range millivoltmeter & power supply for oven.
  • Pointed spring loaded probes ensure good electrical contacts with the sample.
  • Sample crystal (Germanium).
  • Resistivity.
  • Energy band gap.
  • Electrical conductivity.
  • Semiconductor.
  • Four probe.

Principle and Working:
The resistivity of Ge crystal is given by r=(V/I). 2ps,
Where V is voltage, I is current (mA) and s is spacing between two point electrode.
While the energy band gap is given by Eg =(2k loge r)/T
Where T is absolute temperature & k is Boltzmann constant.
In the present setup, the four probes are placed collinearly with equal spacing between them on the sample. The current is passed through the two outer probes and the potential is measured between the two inner probes. The errors due to electrical contacts are absent because the current and voltage leads are separate.


Cat. No. Item Name Qty.
SN168 Four probe experimental setup 1
CK135 Oven 1
C4192 Four probe arrangement 1
R4636 Sample crystal (Ge) 1
SG395 Thermometer 1

Solid State Physics Experiments