Positron annihilation at the Si/SiO₂ interface

Variable-energy positron annihilation depth-profiling has been applied to the study of the Si/SiO2 interface in Al-gate metal-oxide- semiconductor (MOS) structures. For both n- and p-type silicon under conditions of negative gate bias, the positron annihilation S-factor characteristic of the interface (Sint) is substantially modified. Temperature and annealing behavior, combined with known MOS physics, suggest strongly that S int depends directly on holes at interface states or traps at the Si/SiO2 interface.