Low-Energy-Ion-Bombardment Damage in Germanium

Abstract

The depth of damage induced in Ge films by ions of energies of 200–1000 eV has been measured for He, Ne, Ar, and Kr bombardment, the depth decreasing for heavier ions. The effects exhibit saturation at critical ion dosages. From the results the damaged layer is deduced to consist of two main regions. The one nearer the surface consists mainly of lattice disorder plus trapped gas, which extends to a depth of approximately 10 atomic layers at 1000-eV ion energy. The second, lower region consists mainly of gas atoms trapped in the relatively ordered lattice, the depth of this region increasing with decreasing ion mass. It is concluded that focused atom emission observed in diamond-type lattices is due to the undisturbed surface region structure and focusing is weakened by the damage induced by ion bombardment.