[SOLVED] Diode Reverse Bias Current

[noobler]

noob question: I tested a diode fwd bias circuit measuring 12mA. When I applied negative voltage, I am expecting a very small I reading. The source meter can be set to negative voltage. Why am I seeing a negative current value? If I tried to swap polarity of voltage (and sourcemeter set to +V), the current is small but positive. Any ideas? thanks

 

[Jack// ani]

How much current does your meter read under reverse bias? If its no too much, its pretty much usual, else you have broken diode due to reverse voltage breakdown!!

Small reverse bias current is inherent in diodes due to leakage current in opposite direction.

Hope this helps

 

[noobler]

Im using a Keithley 236 as sourcemeter (nA resolution) and I want to minimize connect/disconnect. Setting it to -1V then gives me a negative current, around -60nA to -2nA. When I reversed the wiring and voltage (+1V setting on SM) I get 2-10nA. I dont get it why I get two different readings?

 

[Jack// ani]

That's because characteristic curve of diode is not same on either side. So even if you apply same voltage with different polarity, you can not expect same current flowing across.

BTW, which diode are you testing? Its worth while to have a look at datasheet specs.

 

[noobler]

its a part of an MIC. test spec limit is 200nA. I am not sure on what setup I will use.

---------- Post added at 03:51 ---------- Previous post was at 02:59 ----------

I just did a sweep from +1 to -1 with 0.1 step @1sec delay. Thanks Jack for the help.