# How charge moves through a diode during the reverse recovery time?

My textbook says something like this :
When a diode is switched from forward bias to reverse, the current changes direction but the magnitude doesn't decrease immediately. The charges continue to flow and the diode draws the power from the battery through out the reverse recovery time.

During forward bias, there exist some "excess" minority carriers near the junction. These contribute to the current during reverse recovery time.

In forward bias, negative plate of the battery pushes electrons from n side to the junction, then the electrons recombine with holes and travel in the valence band through the holes of p side and reach the positive plate of the battery. It seems electrons only travel in valence band in p side. I'm happy having this mental picture for the charge movement during forward bias. But I'm failing to visualize a similar picture for the charge movement during reverse recovery time. I keep getting questions like :

1) Does the negative terminal of the battery put electrons at the edge of the p side, then these electrons fall into holes, the electrons then travel through the holes to the junction and they see depletion region! Then what happens ?
2) What happens to the excess minority carries on the p side near the junction ? Do they feel the battery and move to the n side ? Even if they move to the n side, the excess electrons on p side are never going to disappear because an equal number of electrons seem to enter from the negative terminal of the battery... Highly appreciate any help. Thanks!

• current flow in a diode is a mixed flow of holes and electrons, you seem to be concentrating on electrons so only getting half the picture. Check out this link as a general background before getting into the specifics of a semiconductor diode Commented Jun 7, 2017 at 4:38
• Ahh @Neil_UK amasci was my favorite site when I was in high school. I read almost everything in that site! That link doesn't answer the question I've posted. I'm not looking for the accurate quantum mechanical model at this time; if possible I simply want to treat hole as a missing electron and keep going with the cheap model given by my textbook... I know hole is much more than a missing electron, but I don't know enough quantum mechanics to study diodes using fermi dirac stats and other clever ideas :( Commented Jun 7, 2017 at 4:58
• I know the link doesn't answer your specific question. However 'a hole being a missing electron' is just enough information to get you stuck. Treat it as a moving charge carrying entity with mass just like you treat an electron, you don't need the full QM treatment. Think about it, why do you treat an electron as a charge carrying particle? You've never seen one, don't know how they exist in the orbitals of an atom in fixed energy levels, how they get emitted from neutrons in beta radiation, all weird. Why get weirded out by a moving charge carrying hole? Just go with it, as for electrons. Commented Jun 7, 2017 at 5:09
• Excellent. Now if you do want to get slightly more into holes, bear in mind that the contacts to a diode junction are heavily doped N and P type, so the majority (not the only) carrier is electrons in one, and holes in the other. The ohmic junction with metals, in which the only carrier is electrons, occurs way away from the junction, and is a different issue from the diode junction itself. That's where you can, with profit, start thinking about holes being 'missing electrons', at the metal interface. Commented Jun 7, 2017 at 5:26
• Where an electric current flows in a material, the current is the sum of all mobile carriers. In a hot plasma (like the arc of an electric welder), it's a mix of electrons and positive ions, in semiconductors it's a mix of electrons and holes, in ice it's protons, in metals it's electrons. If you connect your battery with metal wires, it's all electron flow in them. If you connect your battery with ice blocks, it's all protons. At the interfaces between different types of material, that's where it's worthwhile to consider the mechanism whereby one type of flow is continuous with the other. Commented Jun 7, 2017 at 5:30