Answer to Question #112710 in Atomic and Nuclear Physics for Amina

Question

Why are there no holes in copper?

Answer 1

Copper belongs to the so-called normal metals.These are substances that have an free electrons in a conduction band [1]. The fact is that when individual atoms are combined into a solid, they come together at such distances that the electronic wave functions begin to change and instead of narrow atomic levels, continuous zones of states of various structures may appear. The structure of the energy bands that arise strongly depends on many factors, for example, on the initial atomic levels and their filling (mainly substances with an unfilled atomic shell become metals) the distances between the atoms and the coordination environment of the atom. The most striking example in this regard is carbon. In the form of graphite it is a conductor, and in the form of diamond an insulator. Copper, like many other normal metals, has a zone shown in the left part figure.

Owing to such a band structure, electrons can freely move through copper, changing their energy by an arbitrarily small amount, i.e. can conduct current. Holes as current carriers arise in a substance in the presence of a completely filled energy zone, which is often found in substances such as semiconductors. In such substances, in order for free charge carriers to arise, electrons need to acquire additional energy in order to transfer to the conduction band. At the same time, empty sites appear in the filled zone that also have the ability to move through the substance. Such current carriers are called "Holes".

Answer: Copper cannot have holes because in its electronic band structure there is no bandgap.

[1] https://en.wikipedia.org/wiki/Electronic_band_structure