Effects of Si and Ti impurities on electrical properties of sol-gel-derived amorphous SrTa_2O_6 thin films by UV/O_3 treatment

摘要

Sol-gel-derived SrTa_2O_6 thin films were fabricated at a low temperature of 500 ℃. To improve their leakage current properties, additional UV/03-assisted annealing was performed from room temperature to 290 ℃. UV/O_3 treatment at 290 ℃ gave a very low leakage current that was six orders of magnitude lower than that of an untreated thin film. During UV/03-assisted annealing, Si and Ti ions diffused from the substrates into the SrTa_2O_6 thin films and occupied the Ta~(5+) sites, subsequently generating Si~- and Ti~-. At a heating temperature of 290 ℃, large amounts of Ti ions diffused throughout the SrTa_2O_6 thin film. These Ti ions contributed to the generation of inactive combinations of (Si~--V_o~+)~+-Ti~- and (Ti~--V_o~+)~+-Ti~-, which greatly reduced oxygen vacancies (V_o). Thus, the leakage current was significantly reduced.