Semiconductor heterostructures

Article By:

Casey, H. C., Jr. Department of Electrical Engineering, Duke University, Durham, North Carolina.

Woodall, Jerry M. Department of Electrical Engineering, Yale University, New Haven, Connecticut.

Last reviewed:January 2020

DOI:https://doi.org/10.1036/1097-8542.614030

Structures consisting of two different semiconductor materials in junction contact, with unique electrical or electrooptical characteristics. A heterojunction is a junction in a single crystal between two dissimilar semiconductors. The most important differences between the two semiconductors are generally in the energy gap and the refractive index. In semiconductor heterostructures, differences in energy gap permit spatial confinement of injected electrons and holes, while the differences in refractive index can be used to form optical wave­guides. Semiconductor heterostructures have been used for diode lasers, light-emitting diodes, optical detector diodes, and solar cells. In fact, heterostructures must be used to obtain continuous operation of diode lasers at room temperature. Heterostructures also exhibit other interesting properties such as the quantization of confined carrier motion in ultrathin heterostructures and enhanced carrier mobility in modulation-doped heterostructures. Structures of current interest utilize III–V and IV–VI compounds having similar crystal structures and closely matched lattice constants. See also: Band theory of solids; Laser; Light-emitting diode; Optical detectors; Refraction of waves; Solar cell

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