Critical-thickness and growth-mode transitions in highly strained In_{x}Ga_{1-x}As films

Singular phenomena in highly strained ${\mathrm{In}}_{\mathit{x}}$ ${\mathrm{Ga}}_{1\mathrm{-}\mathit{x}}$As are used to test current theories of dislocation dynamics in thin films. Strong support is found for a temperature-dependent frictional force which has an activation energy of magnitude of the Peierls energy. With this force, an abrupt temperature-dependent transition in the critical thickness of pseudomorphic growth is explained for the first time; the island-to-layer growth-mode transition which occurs at this temperature is shown to be equivalent to a similar x-dependent transition, and island growth is attributed to nucleation by misfit dislocations.