Ossila Sheet Resistance Software User Manual

Ossila Sheet Resistance Software

Product Information

The Sheet Resistance Software is a software developed by Ossila for measuring the sheet resistance of samples. It is designed to work with the Windows 10 operating system and requires a minimum computer specification of a dual-core 2 GHz CPU, 2 GB RAM, 160 MB available hard drive space, and a monitor resolution of 1280 x 720.

Product Usage Instructions

Requirements

Before installing the Sheet Resistance Software, ensure that your computer meets the minimum system requirements mentioned in Table 1.1.

Installation

1. Insert the USB memory stick provided with the software into your PC.
2. Run the file “Ossila-Sheet-Resistance-Installer-vX-X-X-X.exe” from the USB memory stick.
3. Follow the on-screen instructions to complete the installation of the software.
4. Note: Alternatively, you can download the Ossila Sheet Resistance software from ossila.com/pages/software-drivers.

Operation

Taking a Measurement

1. Place your sample in the center of the vertical stage.
2. Raise the platform until the probes have retracted approximately halfway into their housing.
   • To ensure good electrical contact, make one full turn of the micrometer after initial contact is made.
   • Ensure that the probes make contact with the center of the sample.
   • For rectangular samples, align the longest edge parallel to the probes.
3. Start the Ossila Sheet Resistance software to open the measurement window.
4. Set the desired settings in the software (explained in more detail in Section 3.2).
5. Click the “Measure” button.
   • The software will apply a voltage and measure the current across the sample.
   • The voltage will be increased until either the target current is achieved or the maximum voltage is reached.
   • If the target current is achieved, the sheet resistance will be measured.
   • The measurement will be repeated for the number of times set in the “Repeats” option.

For more troubleshooting information, refer to the Troubleshooting section in the user manual.

Requirements

• Table 1.1 details the minimum computer specifications for the software.
• Table 1.1. Ossila Sheet Resistance software requirements

Installation

1. Install the Ossila Sheet Resistance software on your PC.
   • Run the file ‘Ossila-Sheet-Resistance-Installer-vX-X-X-X.exe’ on the USB memory stick provided.
   • Follow the on-screen instructions to install the software

Note: The Ossila Sheet Resistance software can be downloaded from ossila.com/pages/software-drivers

Operation

Taking a Measurement

1. Place your sample in the center of the vertical stage.
2. Raise the platform until the probes have retracted approximately halfway into their housing.
3. One full turn of the micrometer (after initial contact is made) is a good way to ensure that there is good electrical contact between the probes and your sample.
4. Ensure that the probes make contact with the center of the sample.
5. For rectangular samples, the longest edge should be aligned parallel to the probes.
6. Start the Ossila Sheet Resistance software. The window is shown in Figure 3.1Error. Reference source not found. will open.
7. Set the appropriate settings in the software (explained in more detail in Section 3.2).
8. Click the ‘Measure’ button.

Sheet Resistance Software

• The unit will apply a voltage and measure the current across the sample.
• The voltage will be increased until either the target current is achieved, or the maximum voltage is reached.
  • If the maximum voltage is reached before the target current is achieved the measurement will cancel.
• If the target current is achieved, the sheet resistance will then be measured.
• The measurement will be repeated for the number of times set in the ‘Repeats’ field, and the average will be displayed on the right.
  • These measurements will use the applied voltage found in the initial sweep to supply the current.
• If a thickness has been provided, the average resistivity and conductivity will also be displayed.

If automatic saving is turned on, the measurement data and settings will be saved.

Figure 3.1. Ossila Sheet Resistance software

Software Settings

There are several settings in the program that must be filled in before taking a measurement. These are found in the column on the left of the window. Additionally, information about each setting can be found by clicking the ‘?’ buttons next to each field.

Connection

Connection Type

• Select the type of connection you are using, either USB or Ethernet.
• Any connected units will be automatically detected when a selection is made and the ‘System Address’ box will be populated.
  • To rescan for connected units (in case the connection is changed) click the refresh icon next to the ‘System Address’ box.

Table 3.1. Current specifications for each range of the Four-Point Probe System.

Range| Maximum Current| Accuracy| Precision| Resolution
---|---|---|---|---
1| ±200 mA| ±500 μA| 10 μA| 1 μA
2| ±20 mA| ±10 μA| 1 μA| 100 nA
3| ±2 mA| ±1 μA| 100 nA| 10 nA
4| ±200 μA| ±100 nA| 10 nA| 1 nA
5| ±20 μA| ±20 nA| 1 nA| 0.1 nA

Samples per Point

• Select the number of samples to be taken for each measurement.
• A higher number of samples per point will improve the accuracy and precision of the measurement. However, this will increase the time taken for it to be performed

Measurement

Probe Spacing

• Sets the spacing between each of the probes in mm.
• This is required to determine the appropriate geometric correction factor for the sample being measured.

Target Current

• Sets the current to apply to the sample for the measurement.
• The units and maximum values of this field will be dependent upon the selected Range.
• This value can be positive or negative.
• The value that should be used for this field is dependent upon the resistance of the sample being tested (see Section 3.3Error! Reference source not found.):

Sheet Resistance Software

1. Higher values for less resistive samples.
2. Lower values for more resistive samples

Maximum Voltage

• Sets the maximum voltage in volts that can be applied to the sample to achieve the target current.
• The polarity of the voltage will be determined automatically, based upon the target current.

Voltage Increment

• Sets the step size for changing the voltage when trying to achieve the target current.

Repeats

• Sets the number of measurements that will be taken to generate an average for the results.

Sample Details

Geometry

• Select the geometry of the sample being measured.
• This is required to calculate the geometrical correction factor for the current sample.
• If the shape of the sample is irregular, consider whether it is closer to rectangular or circular and then estimate what size of that shape could fit within the sample.

Long Side (Rectangular Sample)

• Sets the length of the long side of the sample in mm for rectangular samples.
• This is required for calculating the appropriate geometrical correction factor.

Short Side (Rectangular Sample)

• Sets the length of the short side of the sample in mm for rectangular samples.
• This is required for calculating the appropriate geometrical correction factor.

Diameter

• Sets the diameter of the sample in mm for circular samples.
• This is required for calculating the appropriate geometrical correction factor.

Thickness (Optional)

• Sets the thickness of the sample in μm.
• This enables the calculation of the resistivity and conductivity of the sample.
• It is not needed for sheet resistance measurements and can be set to 0 if not known.

Settings Profiles

Save Settings

• Saves the current settings as a profile that can be loaded quickly for use at another time.
• When clicked, you will be prompted to name the settings profile.
  1. If the name is already in use, you will be asked if you wish to overwrite the previous profile.
  2. The name cannot contain the characters: \ / : * ? “ < > |
• The settings profile will be added to the drop-down box using the given name.
• The settings used in the most recent measurement are automatically saved to the ‘Last Used’ profile.

Load Settings

• Opens a dialog box to navigate to a settings file that has been created as part of a previous measurement.
• The settings fields will be populated with the values in the settings file.

Settings Profiles

• Select a saved settings profile from the drop-down box.
• The settings fields will be populated with the saved values.
• Settings profiles can be deleted by selecting the profile and then clicking the red ‘delete’ icon next to the drop-down box.
• The settings used in the most recent measurement are automatically saved to the ‘Last Used’ profile.

Saving Results

Save After Measurement

• When turned on the measurement data will be saved automatically when a measurement is completed.
• Data will not be saved if the measurement is canceled.
• The data will be saved to the location specified in ‘Save Directory’ using the name specified in ‘Sample Name’.

Save Directory

• Sets the location in which to save the results.
• This can be set either by:
  1. Manually typing the directory into the field.
  2. Copying and pasting it from your file explorer.
  3.  Clicking the folder icon, will open a dialog box to allow the selection of a folder to save to.

Sample Name

• Sets the name to append to the saved data files.
  • The name cannot contain the following characters: \ / : *? “ < >

Save Results

• Clicking this button will manually save the measurement results

Saved Data Format

• Add data is saved to .csv (comma-separated value) files.
• Sheet resistance measurement data is saved in the specified directory with the name ‘SAMPLE NAME Sheet-resistance’. It has columns for:
  • Applied outer current (A)
  • Measured inner voltage (V)
  • Sheet resistance (Ohms/square)
  • Resistivity (Ohm.m)
  • conductivity (S/m)
• Current-voltage sweep data is saved into a folder named ‘I-V’ in the specified directory with the name ‘SAMPLE NAME Current-voltage-sweep’. It has columns for:
  • Applied outer voltage (V)
  • Measured outer current (A)
  • Measured inner voltage (V)
• Measurement settings are saved into a folder named ‘Settings’ in the specified directory with the name ‘SAMPLE NAME Settings’.
• This file can be loaded by the software.

Note: If files already exist with the specified sample name, an incrementing number will be appended to the file names, i.e., ‘SAMPLE NAME Sheet-resistance (2)’.

Controls

Measure

• Clicking this button will start the measurement using the chosen settings.
• This button cannot be clicked if the software has not detected a unit.

Cancel

• Stops a measurement that is currently in progress.
• If the measurement is stopped before it completes, any measured data cannot be saved.

Note: If files already exist with the specified sample name, an incrementing number will be appended to the file names, i.e., ‘SAMPLE NAME Sheet-resistance (2)’.

Choosing a Target Current+

The choice of target current will depend upon how resistive the sample is. Lower target currents should be set for samples with higher resistivity and vice versa.

Examples

1. For the 100 nm indium tin oxide (ITO) sample provided:
   • A target current between 1 and 10 mA (Range 2) should be used because the sample is fairly conductive.
   • The sample should have a sheet resistance between 10 and 16 Ω/square (see Figure 3.9).
2. A less resistive material, such as a 100 nm aluminum film (sheet resistance of ~265 mΩ/square):
3. A target current of greater than 10 mA (Range 1) is required to be able to measure a decrease in voltage between the inner probes.
4. More resistive materials (sheet resistance ≈kΩ/square):
   • A target current of 100 – 1000 μA (Range 3) is needed as the resistance of the material prevents higher currents from being reached.
5. If the resistances are higher than that, even lower target currents (Range 4 or 5) will be required.

Best Practice

If you are unsure how resistive your sample is, the best technique for measuring sheet resistance is as follows:

1. Start with Range 1 currents (10 – 200 mA).
2. If these currents cannot be reached, attempt to use Range 2 currents (1 – 20 mA).
3. Keep decreasing the target current and switching to lower current ranges until the target current can be achieved

Troubleshooting

Most of the issues that may arise will be detailed here. However, if you encounter any issues that are not detailed here, then contact us by email at info@ossila.com. We will respond as soon as possible.

system is firmly plugged into the power supply, and that the plug is connected to both the adaptor and a working power socket.
 | The power supply adaptor has a fault.| Contact Ossila for a replacement power supply adaptor.
The software does not start| The wrong version of Windows is installed on the computer.| Install the software on a computer with Windows Vista or newer.
 | The software has not been installed properly.| Try reinstalling the software.
Cannot connect to the system via USB| The USB cable may not be connected properly.| Ensure the USB cable is firmly plugged in at both ends.
 | The USB cable may not be connected to a working USB port.| Try connecting the unit to a different USB port on the computer.
 | The USB drivers may not be installed or may not have installed properly.| Try installing or reinstalling the USB drivers. If the drivers on the USB provided are not working, try following the Windows 7 installation instructions found in the Installation Guide.
 | The USB cable is defective.| Try using a different USB-B cable, and contact Ossila if necessary.
Cannot connect to the system via network| The MAC address of the unit is not registered with the internal network.| Register the system on the network using the MAC address obtained via a USB connection (see Source Measure Unit manual).
 | The Ethernet cable may not be connected properly.| Ensure the Ethernet cable is firmly plugged in at both ends.
 | The Ethernet cable is defective.| Try using a different Ethernet cable.

• www.ossila.com

References

• Software and Drivers | Ossila
• Ossila | Low Price Lab Equipment & Materials | Enabling Science
• Ossila | Low Price Lab Equipment & Materials | Enabling Science
• Software and Drivers | Ossila

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