The Keithley 24XX. Figure 7. Then click the green Run arrow at the top left of the VI. Figure 8. Create an "Enable Auto Range" boolean control by right clicking the "Enable Auto Range" boolean constant and selecting Change to control. Reposition controls on the Diagram for Configure Output and Enable Output nodes to make room for extra controls.
Create a Manual Range control for each Configure Measurement by right clicking each "manual range 1 " terminal and selecting Create control. Rename each control to match the measurement that's being configured, "Voltage Manual Range" for example. Figure 9. Right click terminals and choose Create control to create a control wired to that terminal.
Go back to the Panel by selecting Panel on the View Selector. Place all new controls on the Panel by selecting the Unplaced items box and placing each onto the Panel. You can then place items down one by one on the Panel. Figure Place Controls onto the Panel using the Unplaced items box.
Find the section of the Diagram between the third Configure Measurement node and the Configure Output node. Create some extra space here by holding Ctrl while clicking and dragging your mouse to the right on the Diagram.
Delete the purple Instrument and yellow Error wire connecting the Configure Measurement node and Configure Output node by selecting both wires and pressing the Delete key. Connect the purple Instrument and Yellow error wires between the Configure Measurement node and Configure Output node. To create a constant input for the Auto Zero node so that the Auto Zero is always enabled, create a Constant at the Autozero terminal on the Auto Zero node.
We want users to be able to choose to have the Auto Zero enabled, disabled, or run immediately so we will create a Control at the Autozero terminal. Right Click the Autozero terminal and select Create control. Place the new control on the Panel by selecting the Unplaced items box and placing it onto the Panel. We'll be focusing on the section containing the "Read Multiple Points " Node. Connect the Signal terminal at the top left of the Histogram Node and connect it to the voltage wire.
Wire together the Voltage values so that they feed into the Signal terminal of the Histogram Node. The Histogram Node can be configured with several inputs. Add an input for the number of bins to create by right clicking the number of bins 10 terminal on the left hand side of the Histogram Node and selecting Create control.
Create the histogram graph by right clicking the histogram terminal on the top right hand side of the Histogram Node and selecting Create indicator. Do the same for actual maximum and actual minimum terminals on the right hand side of the Histogram Node. Rename the X and Y axis of the Histogram graph to correspond with the values being measured by clicking on axis label and replacing the text or by clicking on the axis label and changing the Name text at the top of the Configuration Pane on the right.
Select the center of the graph and change the plot type by selecting Bar in the Plots section of the Configuration Pane. Select the number of desired bins in the histogram using the number of bins control.
The default value is Delete the yellow "Error" wire between the two. Expand the Build Array Node to add an extra terminal by dragging down with the mouse after seeing the expansion cursor appear on the bottom of the Node. On the Build Array Node connect the first terminal Element 1 to the voltage indicator wire, Element 2 to the current indicator wire, and Element 3 to the resistance indicator wire.
Put "," into the constant to make the file comma delimited. Then create an indicator for the new file terminal on the top right of the Write Delimiter Spreadsheet Node.
Rename this indicator "New File Path". Wire together the path with new extension terminal on the top right of the Replace File Extension Node to the file terminal on the top left of the Write Delimited Spreadsheet Node. On the Write Delimited Spreadsheet Node create a constant for the top format terminal.
View how to create a Format Specifier by selecting the Write Delimited Spreadsheet Node and selecting Online manual in the Configuration pane on the right. Wire together the appended path terminal on the top right of the Build Path Node to the path terminal on the top left of the Write Delimited Spreadsheet Node. Create a constant for the new extension terminal on the left side of the Replace File Extension Node. Place ".
Wire together the system directory terminal on the top right of the Get System Directory Node to the base path terminal on the top left of the Build Path Node.
Create a control for the name or relative path terminal on the left hand side of the Build Path Node. Rename the control "File Name". Create a constant for the type terminal on the top left side of the Get System Directory Node. The "File Name" control enables users to name the new. Open the Panel by selecting Panel in the View Selector. Place the unplaced controls and indicators down onto the Panel. TestStand is a ready-to-run test management software that is designed to help you develop, execute, and deploy automated test and validation systems faster.
Finally, you can specify execution flow, reporting, database logging, and connectivity to other enterprise systems for your test system. Therefore, there has been no attempt to optimize the code for larger data sets. It is likely that, after a large number of points have been recorded, the rate of measurements will decrease as the computer becomes fully burdened with storing measurements in memory.
When DC mode is operating, you can change the source current or voltage value as well as the compliance value. The changes will be reflected immediately on the instrument. Auto-ranging, integration time, averaging, and sweep delay can also be changed on the fly.
The time between measurements is determined by the software "sweep delay" setting, as well as instrument settings including the selected sensitivity range, integration period, and number of averages. Due to variations in communication and software execution speed, measurements do not occur at precisely timed intervals.
Unlike sweep measurements, the time data values are not based on the instrument's internal timer; rather, they are based on a software timer.
The accuracy of these time values is not specified. Thus, the time data might include a slight long-term drift that might vary from one computer to the next. Also, each data point's time value might differ slightly from the actual time of measurement due to variations in software execution order and speed.
In practice, I have found the time values to be sufficiently accurate for all applications encountered to date. To assist with probing sensitive or fragile devices, this feature provides instant visual or audible feedback when contact has been made.
To use: configure DC voltage source operation at a safe voltage such as 1V, with a reasonable current compliance such as 2 mA; then start DC-mode operation. Set the contact threshold to 0. Then, approach the device with the probe s. Contact feedback will occur once the measured device current reaches 1 mA.
The appropriate values for bias and contact threshold will depend on the I-V behavior of the device under test. When sourcing current and measuring voltage, the contact threshold specifies a voltage below which contact occurs.
Make sure to use a safe voltage compliance if such usage might expose the operator to live probe voltages--and never intentionally touch probes, conductors, or devices while the SMU is ON. Beep means that the computer will play the default Windows notification sound, and that the SMU will beep 24XX series only. The custom commands sweep allows you to manually specify commands to perform sweep types that are otherwise not supported in this software.
These commands are combined with advanced instrument setting commands. In general, 23X-series instruments should use the wait-for-SRQ read method, whereas 24XX-series instruments can be configured either way. In this mode, except for the initial RESET command, no other commands are automatically generated by the software. So, none of the instrument timing settings from the timing and averages tab will be transmitted to the instrument.
To assist in verifying or debugging a custom command sweep, turn on the "debug" option under advanced instrument settings. After the sweep data has been returned, the software will parse the data and display it on the graph. The preferred format commands are:. Example: these commands should perform a pulsed voltage sweep on a SMU.
This program comes from the instrument manual, Table Basic pulse programming example. Wait for SRQ to read? There are several ways to export data from the I-V software: Save data.
This button will open a file dialog to save the I-V data. Copy data. This button copies the data to the clipboard in tab-separated ASCII format, suitable for pasting into most data processing or spreadsheet software. If selected, the analysis results if displayed are also included.
Copy graph as bitmap. To copy the graph as an image, exactly as it is displayed on screen, right-click on the graph area and select "Copy data. Export graph as image or data table. To export the graph in a different image format, or to directly export the data plotted, right-click on the graph area and select the "Export" submenu.
With this approach it is possible to export the graph in vector graphics format emf or eps. To load prior trace data, use the "Load Data" button. The data file format much match that of files saved by this software, i. If trying to import data from other sources, open a previously saved file in a text editor to view the file format.
The software provides numerous options to plot the measured data. The graph mode selector provides the following options: Current vs. Voltage Voltage vs. Current Current vs. Time Voltage vs. Time Power vs. The resistance fit performs a linear fit to a selected region of I-V data, and is useful for these applications.
Drag the graph cursors to indicate the start and stop of the fit range. The default type of fit is a linear regression fit. Options: Hold shift while pressing the resistance analysis button to perform a simple, 2-point fit to the two cursors instead of a regression fit. Double-click the resistance fit button to automatically select the fit range. The software will select the largest span of data points for which valid i.
This is generally useful for linear resistive devices, and is especially useful when using 23X-series instruments, which lack source read-back capability. The 4-point probe is the standard instrument for quickly measuring wafer resistivity, or checking the sheet resistance of an epi or diffused layer.
The probe comprises a Wenner electrode array with four colinear equally spaced electrodes. This configuration is illustrated below, along with the relevant equations. A brief discussion of the theory can be found here , or in any microelectronics fabrication textbook or website.
However, note that terminology and symbol usage vary between authors; make sure to understand the purpose of the lateral correction factor C as used in this software. This software uses the general equations for sheet resistance and resistivity shown above labeled "otherwise".
This resistivity equation already includes the first-order wafer thickness correction factor. This occurs with small wafers, or with small diffusion test areas on a process wafer. The value of C has been analyzed extensively for various test geometries the "Haldor-Topsoe geometric factors" ; as of this writing, two online resources can be found here and here. Most semiconductors have well-established relationships between resistivity and dopant concentrations; as of this writing, a useful online calculator for silicon can be found here.
Double-click the 4-probe fit button to automatically select the fit range. This is particularly useful for 4-probe measurements with 23X-series instruments. The solar cell analysis automatically extracts the open-circuit voltage, short-circuit current, fill factor, and other parameters related to photovoltaic behavior. Efficiency is calculated based on the provided values for the device area and incident power density.
The analysis works regardless of the polarity of the photovoltaic device, i. A graph cursor will indicate the point of maximum power. The software can try to detect suspicious PV analysis results, by looking for non-monotonic fluctuations in photocurrent. The "flicker" parameter sets this threshold.
The analysis will also extract the local slope resistance of the I-V curve at the open-circuit and short-circuit points.
These values can be useful in identifying major problems with shunt and series resistance; however, unless the I-V data is "clean and smooth", these extracted values tend to reflect measurement artifacts. The "slope neighborhood" field sets the number of points over which each slope is calculated.
The diode analysis fits the exponential current-voltage behavior of a semiconductor p-n or Schottky junction diode. The result is a linear fit on a semilog plot, allowing extraction of diode parameters including ideality factor n and saturation current I 0. To use, position the graph cursors to select the region of exponential I-V behavior, i.
Then press the diode analysis button and view the fit on a semilog plot. If the device is at a different temperature, press shift while pressing the diode analysis button. This will bring up a dialog box to input the device temperature.
This occurs automatically during DC measurements. Time" or "Voltage vs. Results will be displayed automatically. As discussed in the description of DC-mode measurements, software timing issues might introduce slight errors in total power and charge calculations.
These errors should be negligible in all but the most demanding applications. Sometimes, the integrated power or charge values will report 'NaN' not a number. This means that the selected time interval contains invalid measurement points, or measurement points from which power or charge cannot be determined. The most frequent cause is that the instrument reported compliance for one or more measurements. The 23X-series source meters lack source-readback capability, thus when compliance occurs, the actual power delivered to the device cannot be determined.
Sweep delay specifies the delay between voltage or current steps in a sweep, and is programmed to the SMU prior to sweep start. Specifically, this setting controls the delay between changing the bias level and beginning the reading s.
Depending on instrument configuration, this delay is usually added to or merged with a default delay for each measurement range. During DC-mode measurements, the sweep delay determines the approximate minimum delay between successive measurements, and is not transmitted to the SMU as part of the measurement process.
Integration period controls analog integration on the SMU. Available integration periods are instrument-dependent. Averages controls digital integration on the SMU. For each data point, the SMU performs the specified number of readings and returns the average as the result. Config delay is a software setting that specifies the approximate time delay between preparing the SMU for a sweep, and commanding the start of the sweep.
Sweeps with many commands or data points might take longer for the instrument to receive and process, and the actual delay between the end of configuration and the beginning of the sweep might be reduced. Note that during DC-mode operation, the SMU bias is applied without any delay; in this case only the first measurement is delayed. Sweep timeout is a software setting that specifies the amount of time to wait for the sweep results to be returned by the instrument.
In the event that a communication or configuration error occurs, this timeout should prevent the software from remaining unresponsive indefinitely. However, if very long sweeps are being performed, a correspondingly longer sweep timeout is required; otherwise the software will timeout without reading the sweep results. Presets provide a way of storing and recalling commonly used sweeps, analysis options, export actions, and graph zoom settings. They are accessed using keyboard shortcuts.
Measurement presets: There are four measurement preset banks, F5-F8. Each preset can be associated with a sweep or DC-mode measurement configuration. Sweep configuration presets can also be associated with an analysis action resistance, 4-probe, solar cell, or diode and an export action save data or copy data. To program a preset e. F5 , first configure and perform the desired measurement.
The F5 indicator will flash on screen. The preset will be associated with whichever sweep type is shown on the screen including all settings for that sweep type , the most recently performed analysis type and options if performed , and the most recently performed export action save or copy, if either. To recall the preset, perform the measurement, perform the analysis, and export the data, double-tap the F5 key. Graph view presets: There are two graph view preset banks, F11 and F The presets store the graph's zoom, display mode, and axis mapping settings.
To recall the graph view settings, press the F11 key. Advanced instrument commands enable custom instrument commands to be integrated within the software's sweep and DC-mode routines. For example, with a instrument in a solar cell testing laboratory, I used the commands shown above to provide an audible beep at the start and end of each sweep, and to control the shutter on the solar simulator.
For shutter control, we fashioned a cable assembly to connect the relevant pins of the digital output connector on the , to the TTL input pins on our solar simulator's shutter. This window shows all commands that are sent to the instrument, and is helpful for identifying syntax errors or invalid command sequences.
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