On ultra-thin oxide/Si and very-thin oxide/Si structures prepared by wet chemical process

• Published in: Applied surface science 2010-07, Vol.256 (19), p.5757-5764
• Main Authors: Pincik, E., Kobayashi, H., Rusnak, J., Kim, W.B., Brunner, R., Malinovsky, L., Matsumoto, T., Imamura, K., Jergel, M., Takahashi, M., Higashi, Y., Kucera, M., Mikula, M.
• Format: Article
• Language: English
• Subjects: Annealing; Aqueous solutions; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Cross-disciplinary physics: materials science; rheology; Crystal defects; Deep levels; Density; Ellipsometry; Exact sciences and technology; Materials science; Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity); Optical constants: refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Optical properties of bulk materials and thin films; Oxidation; Oxides; Passivation; Photoluminescence; Physics; Quantum confinement; Silicon; Silicon substrates; Surface treatments; Very-thin oxide
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2010.03.096

The properties of ultra-thin oxide/Si and very-thin oxide/Si structures prepared by wet chemical oxidation in nitric acid aqueous solutions (NAOS) and passivated in HCN aqueous solutions were investigated by electrical, optical and structural methods. n- and p-doped (1 0 0) crystalline Si substrates were used. There were identified more types of interface defect states in dependence on both post-oxidation treatment and passivation procedure. On samples prepared on n-type Si, continuous spectrum of defect states of 0.05–0.2 eV range and discrete defect traps, ∼ E CB − 0.26 eV and ∼ E CB − 0.39 eV, were found. All mentioned defects are related with various types of Si dangling bonds and/or with SiO x precipitates. Post-metallization annealing of investigated MOS structures reduced the interface defect density and suppressed the leakage currents. It did not change spectral profile of interface defect states in the Si band gap. In addition, there are presented following two optical phenomena: relation between amplitude of photoluminescence signal of NAOS samples and parameters of chemical oxidation process and quantum confinement effect observed on samples containing Si grains of size less as ∼2 nm.