Rapid amorphization in In_xGa_1-xAs alloys at temperatures between 15 K and 300 K

The amorphization kinetics of In_0.53Ga_0.47As and In_0.20Ga_0.80As alloys has been investigated in comparison to its binary extremes as a function of the Ge ion fluence at room temperature and 15 K. The irradiated samples were analysed by means of Rutherford backscattering-channeling spectroscopy using an in situ technique in case of the 15 K experiments. Contrary to the Al_xGa_1-xAs alloys, the system In_xGa_1-xAs does not exhibit amorphization kinetics intermediate between those of its two binary extremes especially at room temperature. For In_xGa_1-xAs a smaller ion fluence is necessary to render the material amorphous at room temperature than GaAs or InAs. This surprising behaviour is explained in terms of differences in the In-As and Ga-As bond-lengths leading to strain at the atomic scale. We suggest irradiation-induced defect clusters or amorphous nuclei in In_xGa _1-xAs may serve to relieve residual strain and, consequently, retardation of dynamic annealing.