Optical properties of GaAs/GaP strained-layer superlattices

Abstract

The optical properties of a novel system, the GaAs/GaP strained-layer superlattice, are studied and compared with a theoretical model. Photoluminescence and photoreflectance measurements revealed that among the set of superlattices under study type-I and type-II behaviors (similar to those found in the lattice-matched GaAs/AlAs system) are present. The evolution of the photoluminescence peaks as a function of temperature and excitation density supported the assignment of the transitions involved. This is to our knowledge the first observation of direct (type-I) and indirect (type-II) transitions in strained-layer superlattices. A comparison with a theoretical model has led to an estimation of the conduction-band offset as 0.4 eV, which is the first value obtained from experiment in a GaAs/GaP heterojunction.