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Delta Mode destroying devices (ESD?)

6220, 6221 Current Sources
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dbellisario
Posts: 4
Joined: December 16th, 2014, 2:43 pm
Country: United States

Delta Mode destroying devices (ESD?)

Post by dbellisario » May 18th, 2015, 12:25 pm

Hi there. I'm using the 6221-2182 setup to make differential conductance measurements.

With resistors, it is working fine, but our devices are very sensitive to static discharge and something in the delta mode setup appears to be destroying them. I know it is the delta-mode setup because the nV meter registers any voltage buildup across the device prior to running the code, and can see that after attempting a differential conductance measurement the gap has blown (nV meter measures overflow voltage across terminals due to ESD.

I have put the commands I use below. Do you see any issues among them, in particular anything that might explain our device failures using the delta mode?

Please feel free to call me - message me for a number since this is a public forum (it appears to be your only means of contact). if it is possible to connect today that would be ideal. Thank you! Darin

I use Matlab via a GPIB connection to control the setup. If you want the actual code for matlab let me know.

I usually operate in the 10-150mV range, uA range, about 2-5 uA steps, similar deltas, 1NPLC integration time on the voltage measurement, 20 millisecond time delay to let it settle (I've found that's necessary, and more effective than the NPLC)


SOUR:CURR:COMP vcompliance
OUTP:ISH OLOW
UNIT:VOLT:DC SIEMENS
CURR:FILT ON
OUTPut:LTEarth ON
SOUR:CURR:RANG maxcurrent
SYST:COMM:SER:SEND "VOLT:RANG:UPP ',num2str(vComp) ,'"
SYST:COMM:SER:SEND "VOLT:NPLC ', num2str(vRate), '"
SOUR:DCON:STARt Istart
SOUR:DCON:STEP Istep
SOUR:DCON:STOP Istop
SOUR:DCON:DELTa Idelta
SOUR:DCON:DELay tDelay
SENS:AVER:STATE OFF
TRAC:CLE
TRAC:FEED SENS1
TRAC:FEED:CONT NEXT
FORM ASC
SOUR:DCON:ARM
INIT:IMM
fprintf(isrc, 'FORM:ELEM READ');
fprintf(isrc, 'TRAC:DATA?');
dIdV = str2num(fscanf(isrc));

fprintf(isrc, 'FORM:ELEM SOUR');
fprintf(isrc, 'TRAC:DATA?');
current = str2num(fscanf(isrc));

fprintf(isrc, 'FORM:ELEM AVOL');
fprintf(isrc, 'TRAC:DATA?');
voltage = str2num(fscanf(isrc));
SOUR:SWE:ABOR

brian.d.smith
Keithley Applications
Keithley Applications
Posts: 402
Joined: June 10th, 2013, 6:00 am
Country: United States

Re: Delta Mode destroying devices (ESD?)

Post by brian.d.smith » May 19th, 2015, 5:06 am

Have you successfully measured your device using the front panel controls? I would not attempt an automated measurement until I know the behavior of the device under various currents and voltages.

What value are you setting voltage compliance to?

If you are measuring millivolts at microamps, I question the need for a delta-mode system. Indeed, if your device is sensitive to a spike, changing current quickly, which is what delta mode is, will induce spikes from any inductance in your cabling V = L * di/dt

My suggestion, using the front panel, is to set the 6221 to 0 amps on the appropriate microamp range, enable the output, measure the voltage with the front panel of the 2182A. This is your device+cables offset, V_o. Watch the voltage reading and look for drift, this will be cabling and connections thermal drift.

Slowly increase current via the front panel until you reach the maximum current you desire. Record the voltage V_1 and current I_1. Your device resistance = (V_1 - V_o)/I_1.

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