Radiative recombination in stressed superlattices

Abstract

The properties of superlattices (SL) formed by layers with different lattice constants differ from the properties of isoperiodic SLs because of the presence in the layers of appreciable stresses containing both hydrostatic and uniaxial components. The energy levels of stressed SLs at a fixed composition of the layers are governed by two mechanisms. First, the energy of the SL bands relative to the bottom of the corresponding quantum wells is determined by the width and depth of the well, as well as by the distance to other wells. In particular, if at a fixed distance between wells, the authors increase their width, the minimum energies of the superlattice bands relative to the bottom of the well will decrease (quantum dimensional effect). This behavior is usually observed in isoperiodic SLs. Second, the energy of the bottom and edges of wells depends on the stresses in the layers, which, in turn, are determined by the thickness ratio of the layers. Thus, if at a fixed spacing between the wells, their width is changed, the energies of the bottom and of the edge of the wells will change. Such behavior is typical only of stressed SLs.