Ossilas四点探针介绍
Part of the Institute of Physics award-winning Ossila Solar Cell Prototyping Platform, the Ossila Four-Point Probe System is an easy-to-use tool for the rapid measurement of sheet resistance, resistivity, and conductivity of materials.
Built with a high-specification Ossila Source Measure Unit at its core, the Ossila Four-Point Probe is a low-cost system that allows a wide measurement range. The probe head uses spring-loaded contacts instead of sharp needles, preventing damage to delicate samples, such as polymer films with thicknesses on the order of nanometres. The price includes a four-point probe, in-built source measure unit, easy-to-use PC software, and an ITO-coated glass substrate. With free tracked worldwide shipping as standard, more laboratories across the globe can now measure sheet resistance to empower their materials characterisation and thin-film development programs.
The Ossila Four-Point Probe is backed by the Ossila Guarantee and is covered by our FREE 2-year warranty.
What is a Four-Point Probe?
The four-point probe is the most commonly-used piece of equipment for measuring the sheet resistance of a material. Sheet resistance is the resistivity of a material divided by its thickness, and represents the lateral resistance through a thin square of conducting/semiconducting material. This measurement uses four probes arrayed in a line, with equal spacing between each probe. A current is passed between the outer two probes, causing a reduction in voltage between the inner two probes. By measuring this change in voltage, the sheet resistance can then be calculated.
Four-Point Probe Measurement Specifications
| Voltage range | ±100 μV to ±10 V |
| Current range | ±1 μA to ±200 mA |
| Sheet resistance range | 100 mΩ/□ to 10 MΩ/□ (ohms per square) |
| Sheet Resistance | Accuracy* | Precision** | Measured at Range |
| 100 mΩ/□ | ±8% | ±3% | 200 mA |
| 1 Ω/□ | ±2% | ±0.5% | 200 mA |
| 10 Ω/□ | ±1% | ±0.5% | 200 mA |
| 100 Ω/□ | ±1% | ±0.05% | 20 mA |
| 1 kΩ/□ | ±1% | ±0.03% | 20 mA |
| 10 kΩ/□ | ±1% | ±0.02% | 2000 µA |
| 100 kΩ/□ | ±2% | ±0.05% | 200 µA |
| 1 MΩ/□ | ±8% | ±0.5% | 20 µA |
| 10 MΩ/□ | ±30% | ±5% | 20 µA |
*Accuracy is the maximum deviation from the true value.
** Precision is the maximum deviation between identical measurements (useful for comparative measurements).
Physical Device Specifications
| Probe Spacing | 1.27 mm |
| Rectangular Sample Size Range | Long Edge Minimum: 5 mm Short Edge Maximum: 60 mm |
| Circular Sample Size Range (Diameter) | 5 mm to 76.2 mm |
| Maximum Sample Thickness | 10 mm |
| Overall Dimensions | Width: 145 mm Height: 150 mm Depth: 240 mm |
Applications
Sheet resistance is an important property of materials, which is commonly used in material characterisation and in the development of thin-film devices such as perovskite solar cells or organic LEDs.
Material Characterisation
Resistivity is an inherent characteristic of a material, and an important electrical property. It can be determined by measuring the sheet resistance of a thin film with a known thickness, making the four-point probe measurement a key technique for the electrical characterisation of materials.
Thin-Film Solar Cells and LEDs
Thin-film devices require thin conducting electrodes that transport electrical charge laterally to be extracted, so materials with low sheet resistances are required to reduce potential losses. This becomes even more important when attempting to scale up these devices, as the electrical charges must travel further along the electrodes before they can be extracted.
Please note, this system is not suitable for silicon or other materials which naturally form insulating oxide layers. To measure such materials, the oxide layer needs to be penetrated by the probes, which may not be possible with the spring-loaded, round tipped probes utilised by this system.
Included with the Ossila Four-Point Probe
The Four-Point Probe Unit
Built-in Ossila Source Measure Unit
The Ossila Four-Point Probe is powered by our Source Measure Unit. Supplied with a 24 V / 2 A power adapter and USB-B cable.
For more information, please refer to the Source Measure Unit product page.
Four-point probe head
Providing a constant contact force of 60 grams, the spring-loaded four point probe head is perfect for delicate samples. The probes are gold-plated to ensure good electrical contact is made without excess force, and are rounded to further prevent them from causing damage to thin films and other fragile samples (note that they are not suitable for silicon or other materials with insulating oxide layers).
Linear translation stage
With micrometer height control and a sample stage with non-slip rubber