Hi guys:
>
> I'm an ME, so I have a basic knowledge of semiconductors, but not as
> in-depth as you EE's.
>
> When a diode is connected in reverse (the direction where current
> doesn't flow), does it behave like an insulator or like a
> semiconductor? In other words, does it have an extremely high
> resistivity, like a dielectric, or does it just have a high
> resistivity and pass some very small amount of current, like a
> semiconductor?
>
> I know about avalanche breakdown; that's not what I'm talking about.
> I'm talking about at voltages below breakdown.
>
> Thanks for any replies.
>
> Don
Check the datasheet specs for the terms Leakage Current or Peak Reverse Current. Typically on the order of a few microamps for small silicon diodes in the region before breakdown. This can be modeled as a high resistance of tens of megohms.
A sample data sheet:
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Beware of another property, junction capacitance, which can be on the order of several picofarads. This can permit AC components of a signal to leak through even when reverse biased.