Optimization of the metamorphic growth of GaAs for long wavelength VCSELs

In this paper, we present the study of the growth conditions of metamorphic GaAs on InP(0 0 1) substrate using gas source molecular beam epitaxy (GSMBE). We examined the influence of various growth parameters, such as growth temperature and Group V pressure, and determined optimized conditions to produce low roughness (11.6 Angstrom rms) GaAs. We also demonstrate the existence of a critical thickness limit under which dislocations are generated, or propagate, in the substrate. We experimented different types of post-growth cooling rates, annealing and observed their influence on the localization of the substrate dislocations. Altogether, these experiments indicate that the metamorphic growth of GaAs on InP is a valid approach for long wavelength vertical cavity surface emitting lasers. (C) 1999 Elsevier Science B.V. All rights reserved.