Titanium oxynitride films for surface passivation of crystalline silicon deposited by plasma-enhanced atomic layer deposition to improve electrical conductivity

For achieving improved electrical conductivity through surface passivation of crystalline silicon, we investigated TiON films by combining TiO2 and TiN deposition cycles in plasma-enhanced atomic layer deposition. To control the composition of the TiON films, a super-cycle—composed of one cycle of TiO2 and x-cycles of TiN—was adopted. The thickness of the films could be precisely controlled on the nanometer and sub-nanometer scale, regardless of the TiO2:TiN sub-cycle ratio. The chemical state, crystalline phase, and interface characteristics of the TiON films were examined. For the TiO2:TiN = 1:20 film, the carrier lifetime was increased from 30 to 243 μs, while the resistivity decreased from 3.1 × 108 to 7.1×10−1 Ω•cm compared to the TiO2 film.