Heterojunctions between group‐III nitride short‐period superlattices

Abstract

Group-III nitride short-period superlattices (SPSLs) and heterojunctions between them are studied theoretically in terms of the parameters, normally invoked for bulk materials. Relationships between the SPSL structure and their macroscopic characteristics, bandgap, band offsets, and polarization, are considered. The SPSL bandgap is found to depend directly on the quantum-well width/composition and on the barrier width/composition via competition between the quantum-confinement Stark effect (QCSE) and miniband broadening. The mean (period-averaged) electric field is shown to break at the SPSL heterojunction. The break depends on the difference in the SPSL macroscopic polarization which is similar to the spontaneous polarization of bulk nitride materials. In contrast to bulk semiconductors, the bandgap and macroscopic polarization of a SPSL can be controlled independently by adjusting the well/barrier width and composition. A light emitting diode (LED) heterostructure containing SPSL regions is discussed to illustrate the contact phenomena occurring at the SPSL junctions. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)