1 keV hydrogen implantation in a-Si and c-Si: Physical vs computational modeling

We have used the codes MARLOWE, CRYSTAL-TRIM, TRIM-SP and TRIM-95, to simulate our experimental data on the penetration of 1-keV hydrogen ions in a-Si and in c-Si in ''random'' and channeled directions. The dominant energy loss mechanism is inelastic for most of the path length of the penetrating ion. The effect of using an impact parameter dependent inelastic energy loss using the Oen-Robinson (OR) model or a drag force as in the LSS and ENR theories was investigated. In the case of c-Si, the data can be reproduced with the OR model using a single set of physical parameters, whereas in the case of a-Si only partial agreement was found. Even though elastic energy loss is not dominant, simultaneous collisions have to be taken into account. Also, the effect of the computationally required maximum impact parameter (imposed by the binary collision approximation) was examined.