The relaxation of Si-doped In0.04Ga0.96As epitaxial layers on (001)GaAs was studied by using in situ high-resolution X-ray diffraction during molecular beam epitaxy growth. By using a novel technique to measure the wafer curvature, 3 regions were identified in the relaxation process as a function of epilayer thickness. At thicknesses below that for multiplication of slow A(g) misfit dislocations, the behaviour was effectively elastic in that there was no detectable change in curvature at the critical thickness for dislocation nucleation. Beyond the thickness at which A(g) dislocations multiplied, there was total or substantial relaxation; with very little increase in elastic strain as a function of thickness in this region (which corresponded to stage-1 of work-hardening in cubic materials). At

much greater thicknesses (corresponding to stage-2 of bulk work-hardening), only partial relaxation occurred as the lattice hardened due to the creation of misfit dislocations. A substantial elastic strain was observed to be locked into highly mismatched epilayers which were many times thicker than the critical value.

Observation of Hardening during Relaxation of InGaAs on GaAs. B.K.Tanner, P.J.Parbrook, B.Lunn, J.H.C.Hogg, A.M.Keir, A.D.Johnson: Journal of Physics D, 2003, 36[10A], A198-201