Four-Point Probe System

Transcription

1 Manual version: 2.0.E Product code: T2001A2 Product version: 2.0 Software version: 1.1 enabling materials science ossila.com

2 Contents 1. Safety Warning Caution Introduction Component List Specifications Requirements Getting Started Software Installation Taking a Measurement Connection System Settings Experiment Parameters Sample Details Saving and Loading Settings Saving Results Controls Choosing a Target Current Troubleshooting Related Products Revision History ossila.com 2 Ossila Limited 2018

3 1. Safety 1.1 Warning To avoid safety hazards, obey the following: Do not leave devices with applied bias or current unattended as a power failure may result in board damage or device damage and potentially hazardous situations. The maximum allowed driving voltage is ±10 V and the maximum current is ±100 ma. Operating the system outside the operational range can cause damage to the device and greatly increase the risk of electrical shock. Do not operate the switches or touch the system when voltage and/or current are applied. 1.2 Caution To avoid damaging devices or equipment obey the following: Do not connect a voltage source to either of the SMUs on the X100 Source Measure Unit as this will damage the system. Avoid electrostatic discharge (ESD) as this may damage the device. To avoid damage, use static discharge and prevention equipment where necessary. Only use the device for the purposes intended (described in this document) Do not expose the device to any inappropriate cleaning fluids or solvents. Follow good practice when setting up the test system. Avoid placing near sources of electromagnetic interference. ossila.com 3 Ossila Limited 2018

4 2. Introduction The Ossila Four-Point Probe System is a low-cost solution for rapid and reliable characterisation of conducting thin films. The compact, vertically stacked design offers the ideal solution for a busy lab where space is at a premium. Operation of the system is controlled by specifically designed software which automatically calculates appropriate geometrical correction factors for the sample to give accurate values for the sheet resistance, and will further calculate resistivity and conductivity if the sample thickness is provided. 2.1 Component List X100 Source Measure Unit 4-Point Probe Head Manual Vertical Translation Stage with Micrometre Baseplate and Top-plate 2 x BNC Cables Spacers and Fittings 18 V DC Power Supply Micro USB to USB A Cable 100 nm ITO Coated Glass Substrate (20 x 15 mm) 2.2 Specifications Measurement Specifications Voltage range Current range Sheet resistance range 100 μv to 10 V 10 na to 100 ma 10 mω/ to 10 MΩ/ Measurement accuracy < ±4% Measurement precision ±0.5% ossila.com 4 Ossila Limited 2018

5 2.2.2 Physical Specifications Probe Spacing Rectangular Sample Size Range Circular Sample Size Range (Diameter) Maximum Sample Thickness Overall Dimensions 1.27 mm Long Edge Minimum: 4 mm Short Edge Maximum: 60 mm 4 mm to 76.2 mm 5 mm Width: 120 mm Height: 100 mm Depth: 300 mm 2.3 Requirements The system requires a computer running Windows (Vista or newer) with an available USB (recommended) or network port. Further details are given below: Monitor Resolution The software requires a monitor resolution of at least 1440 x 900. o The optimum resolution is 1920 x Power The system requires an 18 V DC power supply. A power supply fitting this description is provided along with the system. USB To use the USB, your controlling device should support USB communication. A USB-B cable is supplied with system. NOTE: The USB connection does not supply power to the system. Network The system should be connected to a network supporting 10/100Mbps transmission. DHCP must also be running on the network, and available to the system for the device to operate properly. o To check if DHCP is running on your network you should attempt to connect another device to the network as you would the system. If the device automatically obtains an IP address, then DHCP is working correctly. ossila.com 5 Ossila Limited 2018

6 3. Getting Started Connect the system to your computer using either the USB cable provided, or an Ethernet cable if preferred. Next, plug in the power supply for the system and check that the green ON LED turns on. Both the USB and power cables plug into the ports at the rear of the system. Finally, ensure the switch next to the Vsense being used is in the Off position (Figure 3.1); this isolates the Vsense from the SMUs, enabling accurate measurement of the sheet resistance. Figure 3.1. Vsense switch in the off position. 3.1 Software Installation Run the file Ossila Sheet Resistance Installer.exe on the USB drive provided and follow the on-screen instructions. I. This will install the Sheet Resistance Measurement software. Open the x100-driver folder and run the file Windows 32-bit Xtralien Driver for 32-bit operating systems or Windows 64-bit Xtralien Driver for 64-bit operating systems. I. This will install the drivers for the Four-Point Probe System. II. Alternatively, the drivers may be downloaded from: III. Note, on Windows 10 computers the drivers will install automatically when the system is plugged in. 3.2 Taking a Measurement 1. Place your sample in the centre of the vertical stage. 2. Raise the platform until the probes start raising to ensure good contact with the sample. ossila.com 6 Ossila Limited 2018

7 I. The probes should be in the centre of the sample, with the long edge aligned parallel to the probes if the sample is rectangular. 3. Start the program Ossila Sheet Resistance and the window shown in Figure 3.2 will open. There are several settings in the program which must be filled in before taking a measurement, which are detailed below. Additionally, this information can be found by clicking the help buttons next to each field (labelled? ). Figure 3.2. Layout of Ossila Sheet Resistance Software graphical user interface window Connection Figure 3.3. Connection settings. (I) Connection type Select the type of connection you are using, either USB or Ethernet. I. The program will automatically search for any available X100s connected to the computer and will populate the System Address box. II. To rescan for connected X100s (in case the connection is changed) just select the type of connection being used. ossila.com 7 Ossila Limited 2018

8 (II) System Address Select the COM port or IP address of the connected X100 (USB and Ethernet connection respectively). I. This box will be populated automatically with the address and board number of any X100s connected to the computer via the method selected in the Connection Type box. II. If you are unsure which X100 to connect to, the board number is written on the underside of the board and in the documentation supplied with the system System Settings Figure 3.4. System settings. (I) Current Source Select which number SMU on the X100 the outer probes of the probe head are connected to I. The SMU numbers are labelled on the board and highlighted in Figure 3.5. (II) Voltmeter Select which Vsense on the X100 the inner probes of the probe head are connected to I. The Vsense numbers are labelled (as VS1 and VS2 ) on the board and highlighted in Figure 3.5. ossila.com 8 Ossila Limited 2018

9 Figure 3.5. X100 Source Measure Unit, Vsense and shutter output connection ports. (III) Range Select the range of the SMU to be used for the measurement. I. This defines the upper limit and sensitivity of current measurements that can be performed by the SMU. These values for each range are given in Table 3.1 below. II. The maximum current values for each range are also shown in the range selection box. Table 3.1. Maximum current and resolution for the different range settings for the X100 SMUs. Range Maximum Current Resolution ma 100 μa 2 10 ma 10 μa μa 1000 na μa 100 na 5 10 μa 10 na Warning: The range must be set physically on the X100 using the 5 yellow switches next to the SMU being used (Figure 3.6), as well as being set in the program. ossila.com 9 Ossila Limited 2018

10 Figure 3.6. Manual range switches on the X100. (IV) Samples per Point Select the number of samples to be taken for each measurement. I. A higher number of samples per point will improve the accuracy of the measurement, but will increase the time taken for it to be performed Experiment Parameters Figure 3.7. Experimental parameters settings. (I) 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 range. The value that should be used for this field is dependent upon the resistance of the sample being tested: I. higher values for less resistive samples II. lower values for more resistive samples ossila.com 10 Ossila Limited 2018

11 (II) Maximum Voltage Sets the maximum voltage that can be applied to the sample to achieve the target current (maximum of 10 V for the X100 sourcemeter). (III) Voltage Increment Sets the step size for increasing the voltage when trying to achieve the target current. (IV) Repeats Sets the number of measurements that will be taken to generate an average for the result Sample Details Figure 3.8. Sample Details settings. (I) Geometry Select the geometry of the sample being measured. I. This is required to calculate the geometrical correction factor for the current sample. II. 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. (II) Long Side (Rectangular Sample) Sets the length, in mm, of the long side of the sample if the sample is rectangular. I. This is required for calculating the appropriate geometrical correction factor. II. This has a minimum value of 4 mm, as smaller samples will result in not all probes making contact with the sample. (III) Short Side (Rectangular Sample) Sets the length, in mm, of the short side of the sample if the sample is rectangular. I. This is required for calculating the appropriate geometrical correction factor. II. This has a minimum value of 4 mm, as smaller samples will result in not all probes making contact with the sample. ossila.com 11 Ossila Limited 2018

12 III. If the sample is square set this to be the same as the long edge. (IV) Diameter (Circular Sample) Sets the diameter, in mm, of the sample if the sample is circular. I. This is required for calculating the appropriate geometrical correction factor. II. This has a minimum value of 4 mm, as smaller samples will result in not all probes making contact with the sample. (V) Thickness (Optional) Sets the thickness of the sample in μm. I. Enables the calculation of the resistivity and conductivity of the sample. II. Not needed for sheet resistance measurement, so can be set to 0 if not known Saving and Loading Settings Figure 3.9. Controls for saving and loading settings. (I) Saving Settings To save the current settings for use at another time, click the Save Settings button. I. The user will be prompted to name the settings configuration. If the name is already in use, the user will be asked if they wish to overwrite the previous configuration. The name cannot contain the characters: \ / : *? < > To change the default settings choose the name Default. II. The settings will be added to the drop-down box using the given name. (II) Loading Settings There are 2 ways to load settings: I. Select a settings configuration from the drop-down box. This will load settings that have been saved using the Save Settings button. II. Click the Load Settings button. In the dialog box the opens, select the desired file and click Open. The program will populate the settings fields with the values in the settings file. ossila.com 12 Ossila Limited 2018

13 (III) Deleting Saved Settings Configurations 1. Select the settings configuration to be deleted from the drop-down box. 2. Press the red X button Saving Results The program allows for data to be saved automatically, as well as manually once the measurement is complete. I. To enable or disable automatic saving, choose the appropriate option from the dropdown box. II. For automatic saving, the Saving fields must be filled in before the measurement can start, these are detailed below. III. The Save Results button is enabled once a measurement has been completed. A save directory must be specified. This can be done either by: I. Manually typing the directory into the Save Directory field II. Copy and pasting it from your file explorer, III. Clicking the Select Directory button, which will open a dialog box to allow the selection of a folder to save to. Figure Save settings pane. Enter a name for the experiment in the Experiment Name field. Results can also be saved manually by clicking the Save Results button after a measurement has finished. When saving, a folder with the experiment name chosen will be created in the specified directory and populated with 3 files: I. The data for the initial current-voltage sweep II. The sheet resistance measurements III. The settings of the experiment (this file can be loaded by the program if you wish to use the same settings again). Note, if you forget to change the save file name, your previous files will not be overwritten as the filenames include the time the file was saved. ossila.com 13 Ossila Limited 2018

14 3.2.7 Controls Figure Controls of the Ossila Sheet Resistance Software. 1. Once the settings have been set, click the Measure button and the measurement will begin. I. The X100 will apply a voltage and measure the current across the sample II. The voltage will increase 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. 2. If the target current is achieved, the sheet resistance will then be measured. I. This measurement will be repeated for the number of times set in the Repeats field, and the average will be displayed on the right-side program. II. If a thickness has been provided, the average resistivity and conductivity will also be displayed. The measurement can be stopped by the user by clicking the Cancel button. I. Note that if the measurement is stopped before it completes, the user will be unable to save the experimental data. If any errors occur during operation, a message describing the error will appear at the bottom of the screen. ossila.com 14 Ossila Limited 2018

15 Figure Typical output plots and measurement results of a 100 nm layer of ITO on a 20 x 15 mm glass substrate. 3.3 Choosing a Target Current The choice of target current will depend upon the 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 sample provided: I. A target current between 1 and 10 ma should be used because this sample is fairly conductive. Range 2 should be selected in the program in addition to manually setting range 2 on the X A less resistive material, such as a 100 nm aluminium film (sheet resistance of ~265 mω/ ): I. A higher target current greater than 10 ma is required to be able to measure a decrease in voltage between the inner probes Range 1 should be selected in the program in addition to manually setting range 1 on the X More resistive materials (sheet resistance kω/ ) I. A target current of μa is needed where the voltage drop between the inner probes will be much more significant Range 3 should be selected in the program in addition to manually setting range 1 on the X100. ossila.com 15 Ossila Limited 2018

16 4. Troubleshooting Before we send you your system we run extensive tests to verify that it is stable and working. However, sometimes you may have issues connecting to and using the system. Most of the issues that may arise will be detailed here, however, if there is any issue that isn t detailed that you encounter then please don t hesitate to contact us by at info@ossila.com and we will respond as soon as possible. Problem Possible Cause Action No power/display Software does not start Cannot connect to the system via USB Cannot connect to the system via Network The power supply may not be connected properly. The power supply adaptor has a fault. The wrong version of Windows is installed on the computer. The software has not installed properly. The USB cable may not be connected properly. The USB cable may not be connected to a working USB port. The drivers may not be installed or may not have installed properly. The USB cable is defective. The MAC address of the system is not registered with the internal network. The Ethernet cable may not be connected properly. The Ethernet cable is defective. Ensure the system is firmly plugged into the power supply and the plug is connected to both the adaptor and a working power socket. Contact Ossila for a replacement power supply adaptor. Install the software on a computer with Windows Vista or newer. Try reinstalling the software. Ensure the USB cable is firmly plugged in at both ends. Try connecting the system to a different USB port on the computer. Try installing or reinstalling the drivers, they can be downloaded from the address given in the Software Installation section. Try using a different micro-usb cable (any should work), and contact Ossila if necessary. Register the system on the network using the MAC address obtained via a USB connection (see Source Measure Unit manual). Ensure the Ethernet cable is firmly plugged in at both ends. Try using a different Ethernet cable. ossila.com 16 Ossila Limited 2018

17 5. Related Products ITO Glass Substrates (Unpatterned) S111 FTO Coated Glass (Unpatterned) S301/S302/S303/S304 Full ITO Scale-Up Substrates S281 UV Ozone Cleaner L2002A1 ossila.com 17 Ossila Limited 2018

18 6. Revision History Rev Date Description A Oct 2017 Initial version B Feb 2018 Change company s address C Apr 2018 Updated screenshots and Saving Results section Added Saving and Loading Settings section. D July 2018 Updated instructions for switching the system on. Updated network troubleshooting section. E Aug 2018 Warranty section removed now a separate document ossila.com 18 Ossila Limited 2018