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Having problem with 3 terminal device analyzation

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jjoll1234
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Joined: July 8th, 2015, 6:16 pm
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Having problem with 3 terminal device analyzation

Post by jjoll1234 » July 21st, 2015, 2:37 pm

Hi,
Recently I have started using keithley 2636B sourcemeter. It is my first time using any sourcemeter and so far I have been able to figure out how to sweep for an I-V curve of a two terminal diode but I have a problem with sweeping a 3 terminal devices such as 2N7000 transistor. I am using Ivy app and connecting SMUB to the Gate for STEPPING (Vgs= 3V, 4.6,6.2, 7.8, 9.4) and SMUA to the Drain for SWEEPING, and I am grounding the Source. I have uploaded - of my configuration.
http://imgur.com/a/onPL0

I am using triax to alligator cables to connect the transistor to the SMU channels. Unfortunately the results that I am getting on the Ivy app dont make sense to me (I have uploaded screen shot of my results). Based on the 2N7000 datasheet the I-V curve (Vds over Ids) is different than the strange results that I am getting right now.
http://imgur.com/a/onPL0

I am not sure if something is wrong with my setup or I am not using the app properly. Also I dont know why I cannot sweep the voltage bigger than 20V?? whenever that I want to sweep higher than 20V app says: "to set a level greater than 20v please lower the limit to 100mA or less" but what if I want to sweep it at high voltage with high current? I always set up the limits to the 100V and 1A on the 2636B but when I connect the sourcemeter to my phone and open up the app, it resets back all the current and voltage limits to the 100mA and 20V respectively.

Any idea and feedback would be appreciated.
Thanks

Dale C
Keithley Applications
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Re: Having problem with 3 terminal device analyzation

Post by Dale C » July 22nd, 2015, 10:37 am

Pulse is the only way to get 1A at 100V on the Model 2635B.
Using DC you have run into the 20V, 1A limit.
Take a look at the power envelope in the attached data sheet. (page 4).
Attachments
2600B_SourceMeterSMU_DS2.pdf
(854.16 KiB) Downloaded 1430 times

jjoll1234
Posts: 5
Joined: July 8th, 2015, 6:16 pm
Country: United States

Re: Having problem with 3 terminal device analyzation

Post by jjoll1234 » July 22nd, 2015, 5:42 pm

Dale C wrote:Pulse is the only way to get 1A at 100V on the Model 2635B.
Using DC you have run into the 20V, 1A limit.
Take a look at the power envelope in the attached data sheet. (page 4).
thanks, I am trying to sweep 2N7000. The I-V curve given in the datasheet shows that Vds is being swept from 0 to 5 voltage therefore I think according to what you mentioned, in this case I can use the DC setting (5 volt, 1A) but I am not sure I am getting weird results (as you can see below)
http://imgur.com/a/onPL0

is it possible that something is wrong with the way that I have connected my transistor to the 2636B sourcemeter? my suspicion comes from reference manual pg-80 (http://imgur.com/6PcfdXJ). Because it is showing another cable that is connecting CH B LO to the S terminal on transistor. Since I only had two cables I didnt do that and I just grounded the S terminal.

Andrea C
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Re: Having problem with 3 terminal device analyzation

Post by Andrea C » July 23rd, 2015, 5:44 am

When you connect the LO of the SMU to GND at the three position Phoenix connector on back of 2636B, then the green booted alligator clip of the triax cable on the HI connector is GND/LO.

Your connection of the GND/LO to source terminal of your DUT should be fine.

However I will mention that there should have been a three position screw terminal mating connector in the box with the 2636B that will let you manage the connections of LO the GND a little better than just jamming wires in the connector.

I looked at data sheet of 2N7000 and for the TO-92 package type, it shows that center pin is Gate. It looks like you have the green booted alligator connected to center pin (GND/LO) rather than SMUB. Can you double check device pinout and connections to DUT.

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