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 and p-type semiconductor such as silicon, this is called a p-n junction.
This is not a necessary condition as the only requirement is that the same semiconductor 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.
