Strained Layer Superlattices of GaInAs-GaAs

Abstract

Since the pionneering work of Matthews and Blakeslee [1] on GaAs-GaAsP strained semiconductor superlattices, the improvement of the Molecular Beam Epitaxy (M.B.E.) and Metalorganic Vapor Phase Epitaxy (M.O.V.P.E.) has allowed the growth of numerous strained systems. This development is due to the potential interest of these structures for device applications. Their use broadens the choice of epitaxial materials on a given substrate by removing the drastic condition of lattice matching. In turn, the thicknesses of the sublayers must be kept small enough so that the mismatch can be elastically accomodated inside the structure. By adapting the design parameters of the superlattices, their band gap and mean lattice parameter can be independently varied in wide ranges [2]. Their ability to prevent the propagation of dislocations make it possible to grow good quality thick strained superlattices on a graded buffer layer matching this mean parameter. For the same reason, they constitute interesting buffer layers between two largely mismatched materials [3]. Moreover, the modifications of the properties of the grown semiconductors by the built-in strains they experience make them potentially useful.