Real-time x-ray studies of strain kinetics in ${\mathrm{In}}_{\mathit{x}}$${\mathrm{Ga}}_{1\mathrm{-}\mathit{x}}$As quantum-well structures

A new time-resolved x-ray method of probing the kinetics of interfacial strains in semiconductor heterostructures is presented. High-resolution synchrotron-radiation measurements of the strain relaxation during rapid thermal annealing show that the lattice dilation of an as-grown quantum-well structure is relieved cooperatively by a series of sluggish discontinuous transitions. Well-defined metastable states of strain are observed between the transitions.