COMPUTER STUDIES OF NONSTOICHIOMETRIC RECOIL PRODUCTION IN BINARY COMPOUNDS

Nonstoichiometric recoil production in binary compounds due to ion bombardment induced collision cascades is studied using Monte Carlo simulation. Metallic oxides of the type A(c)O1-c where A is W, La, Mo, Fe, Ti or Al are studied as an example of binary compounds possessing large mass differences of constituent atoms. The deviation from stoichiometry is explored as a function of the concentration of A-atoms. It is shown that when the energy of the incoming projectile is in the range 10-200 keV the ratio of generated A recoils to O recoils per energy interval (the recoil density ratio) is nearly independent of the generation depth and of the energy and mass of the incoming ion. Comparison of simulation results with analytical calculations based on transport equations shows that the recoil density ratio can be obtained from a simple analytical estimate if c less-than-or-equal-to 0.5. An interpolation formula for the threshold energy dependence of the recoil density ratio is given.