Four-Point Probe
Lab Equipment,
Easy and Reliable Characterization of Your Thin Films
Fast and accurate sheet resistance measurements for a wide range of materials
Overview | Specifications | Features | Gallery | Software | In the Box | Accessories | Resources and Support
Quick and easy measurement of sheet resistance, resistivity, and conductivity of thin films. The spring-loaded, rounded contacts allow for high quality surface measurements without damaging delicate samples, making it ideal for characterizing nanometer-thin polymer films. Both models can fit seamlessly into any lab environment thanks to their compact and self-contained design, while the Plus model can take measurements in setups without a PC.
Built with the Ossila Source Measure Unit at its core, the wide current range is suitable for a variety of measurements. Choose the four-point probe for rapid and reliable material characterization.
The Ossila Four-Point Probe was used by NASA in sheet resistance measurements to investigate the effects of space exposure on indium tin oxide coatings.
Non-Destructive Probes
Protect your sensitive samples
Free Software
Keeping your software up to date
Wide Current Range
For versatile sample measurements
Upgrade to Plus
In-built display for quick measurements
Quick Measurements with the Four-Point Probe Plus
Characterize your samples without connecting to a PC. The Four-Point Probe Plus includes embedded software that is easily controlled by the LED screen and keypad.
The system can independently measure the sheet resistance and, after inputting the dimensions and thickness, the conductivity and resistivity of a sample. It also provides real-time display of both the current and voltage between the outer pins and the voltage between the inner pins. For more complex experiments, this model still includes free PC software so you can record your data.
Specifications
| Voltage Range | ±100 μV – ±10 V |
|---|---|
| Current Ranges | ±20 μA – ±200 mA (5 ranges) |
| Sheet Resistance Range | 100 mΩ/sq – 10 MΩ/sq |
For more information on the current ranges, see our SMU specifications.
Equipped with Soft Contact Probes
The Ossila Four-Point Probe is equipped with soft contact probes to reduce the potential of damaging delicate thin films. Our probes have rounded tips (unlike other probes which are like sharp needles) and a larger surface area with a radius of 0.24 mm. The gold-plates probes are mounted on springs to allow them to retract into the probe head when making contact with the sample. This design spreads out the downward force and ensures that a uniform force of 60 grams is applied to the sample.
Please note: at the moment, our 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, which our probes are designed to avoid.
Sheet Resistance
| Sheet Resistance | SMU Accuracy* | Precision | Measured at Range |
|---|---|---|---|
| 100 mΩ/sq | ±8% | ±3% | 200 mA |
| 1 Ω/sq | ±2% | ±0.5% | 200 mA |
| 10 Ω/sq | ±1% | ±0.5% | 200 mA |
| 100 Ω/sq | ±1% | ±0.05% | 20 mA |
| 1 kΩ/sq | ±1% | ±0.03% | 20 mA |
| 10 kΩ/sq | ±1% | ±0.02% | 2000 µA |
| 100 kΩ/sq | ±2% | ±0.05% | 200 µA |
| 1 MΩ/sq | ±8% | ±0.5% | 20 µA |
| 10 MΩ/sq | ±30% | ±5% | 20 µA |
* The probe head can introduce up to 4% additional measurement error.
Physical Specifications
| Probe Spacing | 1.27 mm (0.05") |
|---|---|
| Rectangular Sample Size Range |
Long edge minimum: 5 mm (0.20") Short edge maximum: 152.4 mm (6") |
| Circular Sample Size Range (Diameter) | 5 mm – 152.4 mm (0.20" – 6.00") |
| Maximum Sample Thickness | 8 mm (0.31") |
| Overall Dimensions (W x H x D) | 145 mm x 150 mm x 240 mm (5.71" x 5.91" x 9.45") |
Resistivity and Conductivity Range
As the system measures the sheet resistance of a sample, a general range of measurable resistivities or conductivities cannot be given. This is because the measurable resistivity range depends on the thickness of the sample being tested. The resistivity of a sample can be calculated from its sheet resistance and thickness using the following equation:
The system is capable of measuring between 100 mΩ/□ and 10 MΩ/□, so if we use these values in the formula above with a sample 50 nm thick, then the resistivity (conductivity) range that can be measured by the system will be 5 nΩ.m to 500 mΩ.m (2 S/m to 200 MS/m). If the sample is 400 µm thick, then the resistivity (conductivity) range of the system is 40 µΩ.m to 4 kΩ.m (250 µS/m to 25 kS/m). Below is a table of the resistivity and conductivity ranges of the system for samples with thicknesses of different orders of magnitude:
| Coating Thickness | Resistivity Range | Conductivity Range |
|---|---|---|
| 10 nm | 1 nΩ.m – 100 mΩ.m | 10 S/m – 1 GS/m |
| 100 nm | 10 nΩ.m – 1 Ω.m | 1 S/m – 100 MS/m |
| 1 µm | 100 nΩ.m – 10 Ω.m | 100 mS/m – 10 MS/m |
| 10 µm | 1 µΩ.m – 100 Ω.m | 10 mS/m – 1 MS/m |
| 100 µm | 10 µΩ.m – 1 kΩ.m | 1 mS/m – 100 kS/m |
| 1 mm | 100 µΩ.m – 10 kΩ.m | 100 µS/m – 10 kS/m |
Four-Point Probe Features
Non-Destructive Soft Contact Probes
Designed to measure delicate samples. Rounded, soft contact probes, with a 0.24 mm radius, spread the downward force applied to the sample. The probes are gold plated and mounted on springs for good electrical contact. When making contact, they retract into the head to ensure that a uniform force of 60 grams is applied.
Wide Current Range
Our four-point probe is capable of delivering currents between 1 μA and 200 mA, and can measure voltages from as low as 100 μV up to 10 V. The system can measure sheet resistances in the range of 100 mΩ/□ to 10 MΩ/□, enabling the characterization of a wide range of materials.
High Accuracy
Positive and negative polarity measurements can be performed to calculate the average sheet resistance between positive and negative currents. This eliminates any voltage offsets that may have occurred, hence increasing the accuracy of your measurements.
Linear Translation Stage
With micrometer height control for simple and controlled soft sample contact. The manual knob makes it easy to achieve good electrical contact each time. Plus, the non-slip stage keeps your samples steady and ensures your delicate samples are not damaged by movement during characterization.
Characterize Large Samples
The large stage area means you can characterize larger samples up to a 6 inch diameter (152.4 mm). Larger samples are less reliant on correction factors and provide more accurate measurements when characterizing your materials.
Quick Measurements (Plus model only)
The inbuilt data display includes a bright LCD display and tactile keypad, allowing you to characterize your samples without needing to connect to a PC. Simply plug in the four-point probe, raise your sample so that it makes contact with the probes, and press the OK button.
Four-Point Probe Gallery*
*Photos include both Original and Plus models
Software
Your four-point probe can be controlled using a PC, running our free, user-friendly Ossila Sheet Resistance Lite software. With the Plus model, you can also use the embedded software on the inbuilt data display. Both pieces of software can calculate appropriate geometrical correction factors for the sample geometry and the resistivity and conductivity of the sample to allow for extensive, accurate electrical characterization of materials (if you would like to record your data, you will need to use the Ossila Sheet Resistance Lite software).
The Sheet Resistance Lite software is supplied on the included USB memory stick along with a copy of the user manual and QC data. In addition, the latest version is always available to download for free from our website.
The Sheet Resistance Lite software saves data to comma-separated value (.csv) files, facilitating importing the data into your preferred analysis software. Advanced settings give you greater control over the measurment, allowing you to set voltage and current limits, perform negative polarity measurements, or use probes with different spacings.
Sheet Resistance Lite Software Requirements
| Operating System | Windows 10 or 11 (64-bit) |
|---|---|
| CPU | Dual Core 2 GHz |
| RAM | 2 GB |
| Available Hard Drive Space | 270 MB |
| Monitor Resolution | 1440 x 900 |
| Connectivity | USB 2.0, or Ethernet (requires DHCP) |
In the Box
- Ossila Four-Point Probe with head and stage
- Integrated source measure unit
- Inbuilt data display with sheet resistance measurement capability (T2001A5 only)
- 60 x 60 mm glass substrate coated with 400 – 450 nm of FTO
- Power adapter (24 VDC)
- USB Driver with QC test report & QC test data
- USB-B cable
Accessories and Related Products
Resources and Support
How to Measure Sheet Resistance using a Four-Point Probe
This guide gives an overview of how to use the Ossila Four-Point Probe System, as well as some general tips and tricks for measuring sheet resistance.
Read more...