Understanding Diode Barrier Potential and Its Role in PN Junction Diodes

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The barrier potential in a PN junction diode is often equated with the 'forward voltage' listed in datasheets, as it represents the voltage needed for conduction. When the applied voltage exceeds this barrier potential under forward bias, the diode begins to conduct. The conduction behavior of a diode is not a simple threshold but follows a continuous exponential function, as described by the Shockley equation. This means that while there is a forward voltage, the relationship between current and voltage is smooth and exponential until ohmic effects take over at higher currents. Understanding these characteristics is crucial for accurately interpreting diode behavior in electronic circuits.
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Hi,

For a PN junction diode, am I correct in thinking that the barrier potential (due to depletion region and hole-electron recombination etc.) is the same as the 'forward voltage' quoted on datasheets? Also, when a forward bias condition is created and the applied voltage is greater than the barrier potential, am I correct in thinking that the diode will then conduct?
 
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You've pretty much got it.
 
One thing people don't seem to get is that the conduction of a diode is a continuous exponential function.

From the wikipedia article:
"The diode is commonly said to have a forward "threshold" voltage, which it conducts above and is cutoff below. However, this is only an approximation as the forward characteristic is according to the Shockley equation absolutely smooth".

The flow is exponential relative to the barrier voltage until it is dominated by ohmic effects at higher currents.
 

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