Four Probe Method For Resistivity Measurement

The resistivity of Ge crystal is given by ρ=(V/I). 2πs,
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 log_e 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.

Features:

• Built-in Temperature sensor with seven segment digital display.
• Dual Purpose seven segment digital display.
• Multi-Turn Pot for fine tunning of Current.
• Pointed spring loaded probes ensure good electrical contacts with the sample.
• Different types of Semiconductor Sample can be used for measurement.

Objectives:

• Measurement of resistivity of semiconductor by four probe method.
• Determination of Energy Band Gap.

Technical Data:

• Power supply : Voltage range X1 (0-200.0mV DC) & X10 (0- 2.00 V DC), Current Range 0-20mADC,
• Oven Supply : 60V AC, Heating resistance 35 ohm, Temp. range ambient to 200º C, Fuse 2A
• Temp. sensor : PT100, range -10º C to 250º C
• Four Probe : Spring loaded, Spacing 25mm, Connection Arrangement 4mm safety socket
• Arrangement 4mm safety socket
• Sample : P type Ge Wafer, Size : 12 x14 x 0.5mm Resistivity 1~10 ohm-cm, Orientation<100>

Scope of Delivery:

• 1 Four probe power supply
• 1 P-Type Ge Crystal
• 1 Oven
• 1 Four probe arrangement
• 1 Sample crystal (p-type Ge)
• 1 PT 100, Temperature sensor (Fixed)
• 1 Screw driver
• 1 Power cord
• 1 N-Type Ge Crystal (Optional)