INTERDIFFUSION AND THERMALLY-INDUCED STRAIN RELAXATION IN GAAS/IN0.2GA0.8AS/GAAS SINGLE-QUANTUM-WELL STRUCTURES

Interdiffusion and strain relaxation in 10 nm thick In0.2Ga0.8As/GaAs single strained layers (SL) covered either with a 30 nm or 10 nm GaAs overlayer subjected to rapid thermal annealing have been studied using RBS and channeling. The diffusion constants of In atoms at temperatures T greater-than-or-equal-to 1000-degrees-C have been estimated from the In RBS profiles. It has been shown that the intermixing rate depends on thickness of the GaAs surface overlayer and is faster for a 10 nm capping. Angular scans through the [110] off normal channels were taken to follow the strain in SLs. No evidence of nonsubstitutional location of In atoms nor the formation of misfit dislocations has been found. It is concluded that strain relaxation is due solely to compositional homogenization of heterostructures.