Effect of external bias potential on secondary charged emissions from polycarbonate by C1+ and C8+ bombardments

Atomic dose dependence of the secondary charged emission current during monoatomic ion C1+ and cluster ion C8+ bombardments to an organic insulator was measured at various external bias potentials. The secondary charged emission current for C8+ varied with the external bias potential at a relatively low dose (3 x 1011 atoms/cm2). The external bias potential dependence of the charged emission current became weaker with increasing dose, and the emission current finally became equal to the injected beam current at a relatively high dose (1 x 1014 atoms/cm2). The stabilization of the secondary emission current at 1 x 1014 atoms/cm2 was observed for C8+ bombardment, but not for C1+ bombardment