Homojunction

A homojunction is a <a href="/facts/Semiconductor/zFf3mGTE">semiconductor</a> interface that occurs between layers of similar semiconductor material; these materials have equal <a href="/facts/Band_gap/IjIeh95l">band gaps</a> but typically have different <a href="/facts/Doping_(semiconductor)/WrGdtWnm">doping</a>. In most practical cases a homojunction occurs at the interface between an <a href="/facts/N-type_semiconductor/d9GPL5tV">n-type</a> (<a href="/facts/Donor_(semiconductors)/TuroVQVE">donor</a> doped) and <a href="/facts/P-type_semiconductor/d9GPL5tV">p-type</a> (<a href="/facts/Acceptor_(semiconductors)/WFKD3jha">acceptor</a> doped) semiconductor such as <a href="/facts/Silicon/cgWx0hdr">silicon</a>, this is called a <a href="/facts/P%25E2%2580%2593n_junction/CaKIdLPg">p–n junction</a>. 
This is not a necessary condition as the only requirement is that the same semiconductor (same <a href="/facts/Band_gap/IjIeh95l">band gap</a>) is found on both sides of the junction, in contrast to a <a href="/facts/Heterojunction/mvnxnIU7">heterojunction</a>. 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 <a href="/facts/Band_bending/3G59hpkj">band bending</a>, and a <a href="/facts/Depletion_region/54fB1pfE">depletion region</a> will be formed at the interface, as shown in the figure to the right.

Homojunction open-in-new

Homojunction