Periodic doping structure in GaAs

Abstract

A new type of superlattice consisting of a periodic sequence of ultrathin p- and n- doped semiconductor layers, possibly with intrinsic (i-) layers in between, is considered. In addition to the features related to the subband formation, as known from the study of the familiar heterostructure superlattices of the type GaxAl1−xAs, crystals with doping superstructure also show other intriguing pecularities. A semiconductor miconductor with doping superstructure, in fact, represents a crystal whose band gap and carrier concentration can be tuned within wide limits. In the first part of this review, some of the unique features of this class of materials are discussed. In the second part, approaches for the realization of doping structures and nipi superlattices in GaAs by the technique of molecular beam epitaxy are outlined.