Homojunction

A homojunction is a semiconductor interface that occurs between layers of similar semiconductor material, these materials have equal band gaps but typically have different doping. In most practical cases a homojunction occurs at the interface between an n-type (donor doped) and p-type (acceptor doped) semiconductor such as silicon, this is called a p-n junction.

A homojunction PN junction. The band at the interface is continuous. In forward bias mode, the depletion width decreases. Both p and n junctions are doped at a 1e15/cm3 doping level, leading to built-in potential of ~0.59V. Observe the different Quasi Fermi levels for conduction band and valence band in n and p regions (red curves).

This is not a necessary condition as the only requirement is that the same semiconductor (same band gap) is found on both sides of the junction, in contrast to a heterojunction. An n-type to n-type junction, for example, would be considered a homojunction even if the doping levels are different.

The different doping level will cause band bending, and depletion region will be formed at the interface, as shown in the right figure.

See also
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