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.