heterojunction

A heterojunction is an electrical junction formed between two different materials, typically semiconductors. This junction is crucial in semiconductor devices like transistors and diodes.12

In a heterojunction, two dissimilar semiconductors are brought together. For example, gallium arsenide (GaAs) and aluminum gallium arsenide (AlₓGa₁₋ₓAs) can form a heterojunction. Unique properties arise at the interface of these materials, which are not found in conventional junctions made of a single semiconductor type.3

These unique features allow for the creation of conductive channels at the interface. By controlling the bandgaps and impurity concentrations of the two materials, a channel can be formed that allows a large current to flow. Applying a gate voltage can then alter the channel's conductivity, thereby controlling the current. This principle is utilized in heterojunction field-effect transistors (FETs) to achieve higher operating speeds compared to devices made from a single semiconductor material.3