In order to determine the effect of the interface type upon the accumulation of damage and ion mixing in heterostructures, the damage that was produced by the 77K implantation of single-layer GaAs/AlGaAs/GaAs and double-layer GaAs/AlGaAs/ GaAs/AlGaAs/GaAs heterostructures was investigated by using Rutherford back-scattering spectrometry and transmission electron microscopy. In the case of the single-layer geometry, the degree of disorder increased with depth. The mixing was greater at the AlGaAs-on-GaAs interface than at the GaAs-on-AlGaAs interface. The damage distribution in samples with the double-layer geometry was different in the 2 layers but it was generally similar to that in the single-layer geometry. These trends were observed in samples with Al fractions of 0.6 and 0.2. The results indicated that the migration of charged defects, due to the presence of an implantation-induced electric field, was not responsible for an asymmetry in damage accumulation across the layer, interface disorder and ion mixing, or the initiation of amorphization at interfaces. It was concluded that these effects could be better understood in terms of a depth dependence of the density of cascade events.

B.A.Turkot, B.W.Lagow, I.M.Robertson, D.V.Forbes, J.J.Coleman, L.E.Rehn, P.M.Baldo: Journal of Applied Physics, 1996, 80[8], 4366-71