The rapid amorphisation of In_0.53Ga_0.47As relative to both InAs and GaAs

Rutherford backscattering spectrometry in combination with channeling has been used to compare the ion-irradiation-induced amorphisation of In _0.53Ga_0.47As with that of InAs and GaAs. In contrast to the well-known behaviour of Al_xGa_1-xAs, the ternary alloy In_0.53Ga_0.47As did not exhibit amorphisation kinetics intermediate between those of the two binary extremes. Specifically, the critical nuclear energy deposition required to render In_0.53Ga _0.47As amorphous was less than that of both InAs and GaAs for irradiation temperatures of -196°C and 23°C. This rapid amorphisation resulted from a greater probability for direct-impact amorphisation in the ternary alloy. We suggest irradiation-induced defect clusters or amorphous nuclei in In_0.53Ga_0.47As serve as a means of relieving strain and accordingly exhibit enhanced stability. Such strain is present in the ternary alloy, at the atomic scale, due to the significant differences in In-As and Ga-As bond lengths and the random ordering of In and Ga on the Group III sub-lattice and is manifested by a broadening of the bond length and bond angle distributions.