Dependence of ion sheath collapse on secondary electron emission in plasma immersion ion implantation

The collapse of the ion sheath in front of a dielectric substrate during argon plasma immersion ion implantation is investigated using a Langmuir probe. The probe signals during the buildup and collapse of the ion sheath are recorded from a lime glass substrate with a magnesium metal plate placed on top. The collapsing speed of the ion sheath is shown to strongly depend on the secondary electron emission coefficient of the substrate. The authors’ results show that it is possible to derive secondary electron emission coefficients from insulating materials based on the probe signals.