Evidence for Chemicals Intermingling at Silicon/Titanium Oxide (TiO<i>_x</i>) Interface and Existence of Multiple Bonding States in Monolithic TiO<i>_x</i>

Abstract

Abstract Metal oxides (MOs) are used in photovoltaics and microelectronics as surface passivating layers and gate dielectrics, respectively. The effectiveness of MOs predominantly depends on their structure and the nature of the semiconductor/MO (S/MO) interface. While some efforts are made to analyze interface behavior of a few MOs, greater fundamental understanding on the interface and structural behaviors of emerging MOs is yet to be established for enhanced scientific and technological developments. Here, the structure of atomic layer deposited titanium oxide (TiO x ) and the nature of the c‐Si/TiO x interface on the atomic‐ to nanoscale are probed. A new breed of mixed oxide (SiO x +TiO x ) interfacial layer with a thickness of ≈1.3 nm at the c‐Si/TiO x interface is discovered, and its thickness further increases to ≈1.5 nm after postdeposition annealing. It is observed that both as‐deposited and annealed monolithic TiO x films comprise multiple bonding states at varying film thickness, with an oxygen‐deficient TiO x layer located close to the mixed oxide/TiO x interface. The stoichiometry of this layer improves when reaching the middle and near surface regions of the TiO x layer, respectively. This work uncovers several critical structural and interface aspects of TiO x , and thus creates opportunities to control and design improved photovoltaic and electronic devices for future development.