Oxidation of Si Surfaces: Effect of Ambient Air and Water Treatments on Surface Charge and Interface State Density

Surface sensitive methods, UV-VIS spectral ellipsometry (SE), surface photovoltage (SPV) measurements, and X-ray photoelectron spectroscopy (XPS) measurements were combined to investigate in detail the Si substrate oxidation and resulting interface electronic properties. Various wet-chemical oxidation methods utilizing hot deionized water with different HCl or Ozone content were optimized in order to prepare ultra-thin oxide layers with reproducible oxide thicknesses ( 0.3 to 3.5 nm), low values of interface state densities and well-defined interface charges. The simulation tool ELifAnT (Effective Lifetime Analysis Tool) was utilised to analyse experimental excess minority charge carrier density (Δn) dependent charge carrier lifetimes τeff (Δn), and to establish correlations between preparation induced interface charges Qit and defect densities Dit on both p-and n-type substrates.