Critical layer thickness of GaN thin layers embedded in GaAs

GaAs/GaN/GaAs thin-layer structures were grown by plasma-assisted low-pressure metalorganic chemical vapor deposition. GaN layers were formed by exposing the surfaces of GaAs epitaxial layers to nitrogen-radical fluxes. When the nitrogen amount exceeded that in one-monolayer-thick GaN, drastic deterioration of the GaN/GaAs interfaces and the GaAs cap layers were observed by X-ray diffraction, etch-pit-density measurement and transmission electron microscopy. This suggests that the critical layer thickness of GaN embedded in GaAs is one monolayer thick. (C) 1997 Elsevier Science Ltd.