Second harmonic generation in Si/SiO2 systems.
Second harmonic generation (SHG) has been utilized as a sensitive and non-invasive optical tool to investigate the interface in Si/SiO2 systems. This dissertation encompasses two major topics: 1) Polarization-dependent SHG in Si/SiO2 systems and 2) characterization of boron-induced interface charge traps in Si/SiO2 systems. Polarization-dependent temporal behavior is investigated in these systems by a time-dependent SHG (TD-SHG) approach. A critical polarization angle is defined in which no temporal SHG response is shown in P-polarized SHG signals. The critical angle is observed to be independent of wafer dopant type, doping concentration, oxide type and oxide thickness. During the growth of the oxide in boron-doped silicon, boron atoms migrate into the oxide creating charge traps near the interface. The charge traps induce a built-in DC electric field across the interface. The properties of the boron-induced charge traps are characterized by TD-SHG measurements including the determination of an energy threshold for filling the boron charge traps.