Computer simulation of ion bombardment collision cascades

Abstract

A Monte-Carlo code is described which simulates features of collision cascades due to ion bombardment. The effects of including an energy loss, U, from the recoiling atom during the displacement process is investigated for 0 ≤ U ≤ E_d . Depending on whether U = 0 or U = E_d is used, the fraction of replacement collisions is determined as 0.28 or 0.19 respectively. Also the fraction of energy expended in elastic collisions and displacement events, v(E) is determined dependent upon the value of U. These results are compared to transport theory solutions. Individual collision cascades are generated and quantitative values determined for the ratio between the individual cascade volume and the cascade volume obtained using the longitudinal and transverse moments of the deposited energy distributions evaluated from transport theory by Winterbon. These volume ratios are compared to the equivalent ratio's calculated by Sigmund.