Structural and optical characterization of alternately strained GaAs/GaP/GaAs/InP superlattices grown by atomic layer molecular beam epitaxy

Abstract

A new type of highly perfect strained layer superlattices matched to GaAs substrate is presented. (GaAs)N(GaP)M(GaAs) N(InP)M superlattices with N = 6, 10 and 90 and M = 2 were grown by atomic layer molecular beam epitaxy. In these superlattices, strain in Gap and InP layers has opposite signs enabling us to obtain a mean lattice parameter perfectly matched to the GaAs substrate. Thicknesses of GaP and InP layers are restricted by the critical thicknesses of these materials on the GaAs substrates. The thickness of GaAs layers in the superlattice is not limited and plays the role of tailoring the band gap of the structure, a feature that widens the applications of similar GaP/InP strained layer superlattices. Double crystal X-ray diffraction measurements show that all samples studied have a high crystalline quality, thicknesses of the different layers are very close to the designed growth values, and the superlattices as a whole are coherent with the substrate, indicating the effectiveness of compensating strains in opposite directions in the GaP and InP layers. High resolution electron microscopy analysis shows sharp interfaces with good lateral uniformity. Neither dislocations nor other crystalline defects are observed. © 1993.