Computer evaluation of primary deposited energy profiles in ion-implanted silicon under channeling conditions

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Abstract
Primary deposited energy profiles produced by 40-keV P ions channeled along the [110] direction in silicon are computed. The model takes into account impact-parameter-dependent electronic energy loss and dechanneling mechanisms, such as thermal vibrations, electronic scattering, and a surface oxide layer. The deposited energy is converted to damage by using Kinchin and Pease's model and distributed along the range of primary recoils or dechanneled ions in two ways: either uniformly or localized at the average damage depth, evaluated using Winterbon, Sigmund, and Sanders's theory. The model is tested for the random case with experiments available. When no dechanneling mechanism is present, radiation damage is reduced by a factor of 10 compared to the random case. Thermal vibrations increase damage almost uniformly along all the channeled path, while the oxide layer increases the damage mostly at the surface. The combined effect of these mechanisms gives a reduction of radiation damage of only a factor of [inverted lazy s]2 compared to the random case. The results show also that damage is mostly concentrated at the surface: about 85% in the first 2000 Å compared to a maximum penetration of 7600 Å.