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The structure and stability of isolated amorphous zones, produced by heavy ion irradiation of semiconductors, has been modeled by using the randomization and relaxation method. The evolution of the temperature and the size of the relaxation volume during annealing process was calculated by using the thermal spike model. To extend the method to III–V compounds, we used the Martin potential which takes into account the partly ionic character of the atomic bonds. The “higher-order-neighbours effective order” approximation was introduced to permit the electrostatic part of the potential to be calculated. This model has been used to study the minimum cascade size which is necessary to produce a stable amorphous zone. In addition, an attempt has been made to examine the absence of direct-impact amorphization in the ternary alloy Al x Ga 1- x As (with x ⪆0.5), which is experimentally observed. No significant difference was found between AlGaAs and GaAs, which we attribute to the simplicity of the Martin potential. |
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