Heterostructure

These semiconducting materials have unequal band gaps as opposed to a homojunction. It is often advantageous to engineer the electronic energy bands in many solid state device applications including semiconductor lasers, solar cells and transistors to name a few. The combination of multiple heterojunctions together in a device is called a heterostructure although the two terms are commonly used interchangeably. The requirement that each material be a semiconductor with unequal band gaps is somewhat loose especially on small length scales where electronic properties depend on spatial properties. A more modern definition may be to say that a heterojunction is the interface between any two solid state materials including crystalline and amorphous structures of metallic, insulating, fast ion conductor and semiconducting material.

In 2000, the Nobel Prize was awarded with one half jointly to Herbert Kroemer (University of California at Santa Barbara, California, USA) and Zhores I. Alferov (A.F. Ioffe Physico-Technical Institute, St. Petersburg, Russia) for "developing semiconductor heterostructures used in high-speed- and opto-electronics".