# Holes as positive charge carriers in semiconductors

1. Sep 12, 2015

### fog37

Hello Forum,

An electric current is the flow of electric charge: charge in motion. The charges can be electrons, ions, etc. movingi in a solid, liquid, gas.

When dealing with semiconductors the concept of hole is introduced. I understand that only the electrons are moving and the constitute the real, actual particles. Holes are just a vacancy of electrons and have positive charge.

The concept of hole must have been introduced because of some mathematical convenience in dealing with energy levels discussions, etc... I would like to appreciate a little more why the concept of hole was introduced. It must make life easier or some explanations more clear...

Can anyone add any further conceptual explanation of why the concept of hole is so useful? If we only used electrons, would the theory become really mathematically untreatable?

thanks,
fog37

2. Sep 12, 2015

### Staff: Mentor

Note that the "electrons" considered in semiconductors are quasiparticles as well. They have the same charge, but their mass is different from the electron mass.
In nearly every aspect, holes act like real particles. They have a mass, they react to electric and magnetic fields, they lead to a different Hall effect (try to describe this with moving electrons - you'll get the sign wrong), and so on.

Describing everything in terms of electrons with the electron mass would be really messy.

3. Sep 12, 2015

### Legolaz

They come in pairs, married to one another if and only if additional energy is applied.

You may think this way with the figure, the atomic model : Stable elements usually has the same number of electrons, protons and nuetrons.
Electrons around the orbitals are fixated or attracted by opposite charge protons, but the only thing is, electrons are arrange in energy levels or orbitals. The farthest or the outer most orbitals experienced low attraction force as compared to the nearest 2s electrons, so more often if a force field is applied to it, which is greater than the binding force of the atom's protons, electrons at the outer shell will be easily displaced. Once displaced, this will result to a positively charge atom-meaning electrons are missing, obviously. When electrons are missing, we term this as "hole", could be similarly thought as "electron vacancy" -my personal term.

Last edited: Sep 12, 2015
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