Atomic Layer Deposition of Titanium Oxide-Based Films for Semiconductor Applications-Effects of Precursor and Operating Conditions.

Two widely used atomic layer deposition precursors, Tetrakis (dimethylamido) titanium (TDMA-Ti) and titanium tetrachloride (TiCl 4 ), were investigated for use in the deposition of TiOx-based thin films as a passivating contact material for solar cells. This study revealed that both precursors are suited to similar deposition temperatures (150 °C). Post-deposition annealing plays a major role in optimising the titanium oxide (TiO x ) film passivation properties, improving minority carrier lifetime (τ eff ) by more than 200 µs. Aluminium oxide deposited together with titanium oxide (AlO y /TiO x ) reduced the sheet resistance by 40% compared with pure TiO x . It was also revealed that the passivation quality of the (AlO y /TiO x ) stack depends on the precursor and ratio of AlO y to TiO x deposition cycles.