A GENERALIZED TRANSPORT-EQUATION FOR ION-IMPLANTATION INTO INFINITE TARGETS

In this paper a transport equation (TE) is derived which incorporates arbitrary distribution functions and a cut-off energy. Integral equati ons for the gas-like and liquid free-flight path length distribution m odels are both incorporated into the transport theory computer code KU BBIC using the two-parameter differential nuclear scattering cross sec tion. Simulations for the ion As implanted into a-Si are compared with those performed using a parallel processor Monte Carlo (MC) code base d on TRIM. Excellent agreement is obtained when using four versions of the liquid model, including use of the Biersack free-flight path exte nsion formula and the time integral hard sphere approximation. In addi tion, the effects of varying the maximum impact parameter are investig ated as is the effect of the ordering of nuclear and electronic intera ctions. The TE formalism and solver presented in this paper serve as a powerful tool for testing new approximations which may be incorporate d into MC codes in order to improve computational efficiency.