Determination of the Band Structure and Conductivity of the Si@O@Al Nanocomposite

The purpose of this work is to study the characteristics of the junction between the titanium down conductor of a thin-film solid-state lithium-ion battery ($a$-Si) and a negative Si@O@Al nanocomposite electrode. The results of measuring the band gap of the Si@O@Al nanocomposite and the height of the Schottky barrier of the Ti-Si@O@Al junction are presented. The transmission and reflection spectra of Si@O@Al films and its main phases $a$-Si, $a$-SiO$_x$ and $a$-Si(Al$_x$) are studied. The band gap of Si@O@Al was determined by the Tauc method, which is 1.52 eV for $a$-Si and 1.15 eV for $nc$-Si. The IV characteristics of Ti|Si@O@Al, Ti|$a$-Si, Ti|$a$-SiO0.8, and Ti|$a$-Si0.9(Al0.1) structures have been studied and the height of the Schottky barrier has been determined. The results obtained make it possible to estimate the Fermi energy of the nanocomposite and to interpret the hike in the SSLIB charging voltage as a result of the Al acceptor impurity compensation during lithiation. A change in the majority charge carriers in Si@O@Al leads to a decrease in the hole current and an increase in the density of the over-barrier electron current, as a result of which a step with a height of 1.5 V is formed on the charging curve.