Four Probe Set-up (Research Model)

We offer Four Probe Method is one of the standard and most widely used method for the measurement of resistivity. In its useful form, the four probes are collinear. The error due to contact resistance, which is significant in the electrical measurement on semiconductors, is avoided by the use of two extra contacts (probes) between the current contacts. In this arrangement the contact resistance may all be high compare to the sample resistance, but as long as the resistance of the sample and contact resistance's are small compared with the effective resistance of the voltage measuring device (potentiometer, electrometer or electronic voltmeter), the measured value will remain unaffected. Because of pressure contacts, the arrangement is also specially useful for quick measurement on different samples or sampling different parts of the sample.

The experiment consists of the following:

1. Probes Arrangement, FPA-RM:
The probes arrangement is mounted in a suitable stand, which holds the sample plate and RTD (A class) sensor.

2. PID Controlled Oven, PID-200

Temperature Range: Ambient to 200°C   
Resolution: 0.1°C
Short Range Stability: ±0.2°C     
Long Range Stability: ±0.5°C
Measurement Accuracy: ±0.5°C (typical)
Oven: Specially designed for Four Probe Set-Up
Display: 3½ digit, 7 segment LED with autopolarity

3. Constant Current Source

a) Constant Current Source, Model : CCS-01
(for low resistivity samples)
The current source is suitable for the resistivity measurement of low to medium resistivity samples such as thin films of metals/ alloys and semiconductors like germanium.

Specifications
Open Circuit Voltage: 12 V
Current Range: 0-20mA, 0-200mA
Resolution: 10μA
Accuracy: ±0.25% of the reading
Display: 3½ digit, 7 segment LED
Load Regulation: ±0.1% for 0 to full load
Line Regulation: ±0.1% for 10% changes

b) Low Current Source, Model : LCS-02
(for high resistivity sample)
This current source is especially suitable for the resistivity measurement of polymer ceramics and Si crystals.

Specifications
Open Circuit Voltage: 15V
Current Range: 0-2μA, 0-20μA, 0-200μA & 0-2μA
Resolution: inA at 0-2μA range
Accuracy: ±0.25% of the reading ±1 digit
Display: 3½ digit, 7 segment LCD with autopolarity
Load Regulation: ±0.1% for 0 to full load
Power: 3 x 9V batteries

4. D.C. Microvoltmeter, DMV-001

Range: 1mV, 10mV, 100mV, 1V & 10V with 100% over-ranging.
Resolution: 1μV.
Accuracy: ±0.2%.
Stability: Within ±1 digit.
Input Impedance: >1000MΩ (10MΩ on 10V range).
Display: 3½ digit, 7 segment LED with auto .polarity and decimal indication

The experiment complete in all respect