I know that when the anode is at a higher potential than the cathode the diode is said to be forward biased and current can flow.

My question is this:

If the anode and the cathode is at the same potential, is the diode said to be forward biased, reverse biased, or what?

I know that an ideal diode doesn't exist and that no current will ever flow if there is zero potential difference. I'm more concerned with the correct terminology to use for this situation.

 

Non-conductive.
Similar to the effect you get when you test a diode with a VOM on the resistance range it appears open, as there is insufficient current to forward bias it.
Max.

 

Or zero-biased.

 

I know that when the anode is at a higher potential than the cathode the diode is said to be forward biased and current can flow.

My question is this:

If the anode and the cathode is at the same potential, is the diode said to be forward biased, reverse biased, or what?

I know that an ideal diode doesn't exist and that no current will ever flow if there is zero potential difference. I'm more concerned with the correct terminology to use for this situation.

Hi there,

If there is no potential difference then there is no current flow, and that is not just with a diode, that is with any two terminal device. Even a direct short circuit will not conduct current if there is no potential difference, and that idea is actually used to simplify some circuits.

In practice the regular Si diode requires a little voltage to start conducting with some small current, somewhere around 0.4v at room temperature. Some Schottkey diodes though will conduct significantly even with 0.2 volts difference. Germanium diodes conduct sooner too.

There is also a tiny current in the reverse direction due to leakage, but with zero voltage difference this wont happen either.

 

I did the experiment with a junction transistor and tracked it down to a nano-amp. I suspect from the curves published for diodes, this is true for them, but zero is zero and that makes your question easy to answer.