Arsenic implanted specimens after liquid phase epitaxy followed by annealing treatment were studied in the range 450° C-900° C. A detailed analysis of As and interstitial profiles reveals that arsenic diffuses, starting from 550° C, in two stages : as an interstitial-arsenic complex for 550° C ≤ T ≤ 650° C and independently of interstitials for T ≥ 750* C. It is shown that interstitials are created during the liquid to solid transformation prior to the annealing treatments.