Disorder saturation in heavy ion implanted semiconductors

Studies of ion implantation induced disorder production in Si, GaAs and InP as a function of heavy ion fluence are examined for similarities. In all cases disorder increases rapidly then reaches a quasi saturation with increasing fluence. The 'knee' at which the transition to quasi-saturation occurs is identified, from disorder-depth distribution function measurements, as corresponding to production of a continuous amorphous layer. The thickness of this layer is found, for all three substrates and a range of ion species and energies to be well described by the relations: X=X_d+(2.7×0.5)ΔX_d where X_d is the mean damage depth and ΔX_d is the standard deviation of damage profile. This allows reasonable prediction to be made of critical fluences required for initial amorphous layer production.