Problems in Keithley 4200-SCS Labview Driver

[HoffyReg]

I am using labview drivers for Keithley 4200-SCS, downloaded from Tektronix official website: https://www.tek.com/software/4200-scs-labview-lv-version-7-driver-beta-release-25mb

I take a test by measuring the I-V curve of a resistor on a probe station using KITE in 4200-SCS or using Labview program KI4200.vi. Parameters in two cases are all the same but the results don't agree with each other. And I find even when there is no device on the probe station, test using  Labview still gives the same result as there is a resistor. So I guess there must be something wrong with the drivers.

Attached are the curves I get. Thank you in advance for your answer.

[HoffyReg]

I am using labview drivers for Keithley 4200-SCS, downloaded from Tektronix official website: https://www.tek.com/software/4200-scs-labview-lv-version-7-driver-beta-release-25mb

I take a test by measuring the I-V curve of a resistor on a probe station using KITE in 4200-SCS or using Labview program KI4200.vi. Parameters in two cases are all the same but the results don't agree with each other. And I find even when there is no device on the probe station, test using  Labview still gives the same result as there is a resistor. So I guess there must be something wrong with the drivers.

Attached are the curves I get. Thank you in advance for your answer.

[JustNI]

Hi HoffyReg,

The drivers you mentioned were developed by Tektronix and are marked as being beta builds that aren't guaranteed to work, have you gotten in contact with them about this? Since they're the ones who developed it they'll have access to the resources to understand what might be happening

[HoffyReg]

I think so. I will try to contact them. Thank you.

[cstorey]

Show your code. Withe the settings you used saved as defaults!

The Keithley drivers are fairly generic and does work, they like Google marked everything beta for a long time.  I imagine your SMU setups are incorrect. 

The K4200 can be configured a lot of different ways and you need to pay careful attention to what SMUs you have installed and specify all their settings in your code.  

[HoffyReg]

Attached are the settings I used. SMU1 and SMU3 are drain and source. SMU2 and SMU4 are not enabled. The settings of SMUs are also used in KITE, which gives normal curves. 

I am not familiar with controlling SCS4200 using Labview, so I might make some mistakes without awareness. I will appreciate it very much if you point them out. Thank you.

[cstorey]

Hmm.. From what you show, the instrument performs exactly the measurement you specify.  Your setup looks fine!

It sweeps -0.1V..to..+0.1V and measures current Id.  The resistance Rds is 10kOhms.

In the Kite example you plot the absolute value of current ( Is, Id ) and measures 20 ohms.  Now is that for Is or Id? The Y-axis says both with Is first, but I only see one plot.  Try plotting just Id and see what that is.

Post photo of your Kite setup also.

[HoffyReg]

Since it is a resistor and I used only two SMUs, Idrain should be equal to Isource (for absolute value). So I don't think that is the point. Attached are the settings for KITE example.

The main problem of the Labview program is that, even if I remove the resistor, separate the two probes I used, and then take the measurement with the same SMU settings, the Labview program gives the same Id-Vd curve (10kOhms) just as there was a resistor connected to probes. But in KITE, the resistance rise to (10^16 Ohms). It doesn't make sense.

Have you ever managed to take a correct measurement using the KI4200.vi to control 4200SCS? I'm not sure whether there is something wrong in the drivers or it's just my fault.

[cstorey]

Hmm, so you do have a 20Ohm resistor there?

In Kite what happens if you set SMU1/3 to measure with full auto-ranging, not 100pA limit.

In Kite can you swith to the 2 wire resistor setup and re-measure.

Its strange that you see 10kOhms no matter what.  I know there are options to attenuate or add resistors inline with SMUs, perhaps you need to make sure you do a reset of 4200 before running the code. 

I note that the Keithley 4200 detects pre-amplifiers but these are not configured here.  Are these setup properly?  I've never used the pre-amps or coded for them.  I'd read the manual and SCPI commands to control those.  500x amplification is what you are seeing!

Its been a long time (2001?) since I automate the 4200.  It was LabVIEW 7.  It worked, but took some time with the manual to get all the commands and the proper order of commands to get it working.  The instrument isn't here anymore unfortunately.  

[HoffyReg]

What I measured is a metal paddle evaporated on a wafer. The resistance should be ~10Ohm which agrees with the result of KITE. So  I think KITE is good.

I take further tests and I find that the Labview driver does send correct GPIB commands to KI4200. However, it still gives a IV curve of 10kOhm resistor. Pretty strange.

Maybe there are some settings problems in my system. I'll check it and take a test without preamps.

Thank you very much!