Damage production in a-Si under low-energy self-atom bombardment

Using a molecular-dynamics simulation, we study the buildup of damage in an a-Si specimen bombarded by Si atoms with energies between 10 and 150 eV for fluences up to ${\text{1.4×10}}^{15}{\mathrm{ cm}}^{\text{−2}},$ i.e., an equivalent of 2 monolayer growth. The production rate of overcoordinated atoms increases with the bombarding energy; we analyze its fluence and bombarding-energy dependence in detail. The number of undercoordinated atoms decreases for low-energy bombardment due to the saturation of dangling bonds at the surface; for higher bombarding energies, it increases slightly, but shows only little dependence on bombarding energy. The depth distribution of the damage, of the induced stress, and of the atom relocation in the target demonstrate that bombardment modifies the target at considerably greater depths than the ion range.