# Drift current in PN Junction

Ok guys, first of all thanks for your support and your help, I can't understand how the drift current work, let's say that we have this junction

By the definition of the drift current we can understand that this current is made from minority carriers, so it is made between the holes in the N region and the free electrons in the P region (The minority carriers) but how can the drift current flow if the free electrons in the P region are pushed away from negative zone of the depletion zone that attract holes, and the holes in N zone are pushed away from the positive zone of the depletion region (That will attract free electrons), so if the minorities carrier are pushed away how can this current flow?Thanks for read have a great day :)

By the definition of the drift current we can understand that this current is made from minority carriers, so it is made between the holes in the N region and the free electrons in the P region (The minority carriers)

Both majority and minority carriers can participate in drift current, not just minority carriers. However, pn junction diodes are considered a "minority carrier device" due to the current control coming from the diffusion of minority carriers.

Drift current occurs whenever there an some electric field that causes the carriers to exhibit a net flow. There is no reason an electric field would effect just the minority carriers.

but how can the drift current flow if the free electrons in the P region are pushed away from negative zone of the depletion zone that attract holes, and the holes in N zone are pushed away from the positive zone of the depletion region (That will attract free electrons),

Exactly what you describe is what causes the drift current. I'm unclear about why you think it doesn't.

The electric fields created in the depletion region by the ionized dopants are what create the electric field leading to the drift current. A free electron in the depletion region will be forced toward the N side of the junction (right in your picture) and a hole will be forced toward the P side of the junction (left in your picture).

A diode in equilibrium is a balance of drift and diffusion currents that at equilibrium exactly cancel each other out.

The minority carriers (holes in the n-type and electrons in the p-type) aren't pushed away from the depletion region because there is no electric field outside the depletion region (under equilibrium with no externally applied voltage).

To understand why, look at the electric field of an infinitely large sheet of charge. The electric field is constant, regardless of your distance from the sheet of charge. Electric field due to an infinite thin flat sheet of charge

Now take two infinite sheets of equal but opposite charge in parallel. The electric field between the sheets combine to form a uniform field from the positive to the negative sheet, but outside the sheets of charge the electric fields cancel out.

Images Source: Electric field in a parallel plate capacitor

If you think of the depletion region as two sheets of infinite charge, you can see why there is no electric field outside the depletion region. A hole in the n-type material that gets close to the edge of the depletion region would feel an electrostatic repulsion from the uncovered positive atoms and an equal-but-opposite attraction to the uncovered negative atoms, resulting in zero net force. This is also why the free electrons in the n-type material and free holes in the p-type material aren't attracted to the edge of the depletion region.

I know this question is old, but I was struggling with the same thing so I wanted to post what I figured out.