Influence of electrolyte selection on performance of tantalum anodic oxide memristors

Anodic memristors obtained by electrochemical anodization of Ta in phosphate, borate and citrate buffer solutions are studied. Memristive behaviour is demonstrated by electrical switching between high and low conductive states. The endurance and retention of devices are analysed. The use of phosphate leads to 4 switching levels and the highest ratio between high and low resistive states. All studied oxides are stoichiometric Ta2O5 and only P is detected inside anodic memristors. The improved memristive characteristics of oxides anodized in phosphate are attributed to an increase of O vacancies due to the presence of Ta oxyphosphate, which is believed to mediate spatial pinning of conductive filaments positions during read/write. The anodic memristors show high stability, enhanced endurance and retention that combined with their active layer low fabrication cost makes them ideal candidates for industrial implementation.