Four Probe Tester

Four probe tester is a dedicated instrument for semiconductor materials or bulk materials (sheet resistance). It can be used to test the resistance and sheet resistance of silicon wafers, diffusion layers, epitaxial layers, ITO conductive films, metal films and other materials.

The four-probe test technology is to use 4 equally spaced probes to stick on the surface of the semiconductor, and the constant current source provides an appropriately small current I to the two outer probes, and then measures the voltage V between the two middle probes to obtain the resistivity of the semiconductor.

1. The resistivity of a solid conductor can be measured by Ohm's law and the law of resistance.

2. The resistance obtained by the test can be converted to obtain the conductivity.

3. The relationship between conductance and resistance, if R is resistance (unit: ohm, Ω), conductance is G (unit: Siemens, S), then G = 1/R.

4. Resistance = square resistance × film thickness.

Sample Requirements

• Powder samples need to be pressed into tablets before testing, the mass is greater than 50 mg or the volume is greater than 2 - 3 ml.
• Thin film, providing accurate film thickness and uniform thickness.
• The block sample is parallel up and down, and it is best to polish it.
• The sample size should be at least 10 mm in diameter or length at room temperature.
• The size of the variable temperature sample is less than 10×10 mm, and the thickness is greater than 0.3 mm and less than 2 mm.
• The surface is clean and does not pollute the probe.
• Note: Powder compression will affect the test results, free retesting is not supported, and sample delivery after tablet compression is supported.

Application

• Semiconductors and solar cells (monocrystalline silicon, polycrystalline silicon, amorphous silicon, perovskite)
• LCD panel (ITO / AZO)
• Functional materials (thermoelectric materials, carbon nanotubes, graphene, silver nanowires, conductive fiber cloth)
• Semiconductor process (metal layer / ion implantation / diffusion layer)

Instrument and Result Display

FAQ

Q1. Is the test square resistance or surface resistance?

A. Square resistance.

Q2. Why is there no data for the four-probe test sample?

A. The four probe test is generally fine for conductors. If there is no result, most of the reasons are that the resistance value is out of range.

Q3. For the four-probe resistivity test, does the size and thickness of the sample affect the result?

A. The size generally requires more than 10×10 mm, or at least one side of the long strip is larger than 10 mm, so as not to place the probe. The thickness does not exceed 3 mm, and the correction factors are different for different thicknesses. If the thickness exceeds 3 mm, the 3 mm thickness factor is used for correction by default, and the result will have a certain error.

Recommended Projects

For more information about our four probe tester testing services, please contact us.