Validation and extension of the temperature extraction method of conductive filaments in resistive switching materials

The resistive switching (RS) effect is among the leading future non-volatile memory technologies; however, its implementation is hampered by the lack of full understanding of the switching and conduction mechanism. The switching is generally attributed to the formation and rupture of conductive filaments in the oxide, which are generated by temperature-enhanced nano-ionic and thermal effects. One of the main experimental challenges in studying the RS effect is monitoring of the local filament temperature. We have recently presented an experimental approach for evaluating the conducting filament temperature using a metal-insulator-semiconductor bipolar transistor (MIS-BT) structure [1]. To the best of our knowledge, there are no alternative method to obtain this information, which is of crucial importance for understanding the physics of the formation and rupture of the conducting filaments [2]. The detected temperatures in the experiments reported in [1] were much higher than ambient temperature due to Joule heating of the filaments. To verify the method, it is desirable to extract the filament temperature at much lower current levels, when no significant Joule heating occurs. However, due to the limitations explained below, we were previously not able to extract the temperatures at sufficiently low current levels. Here, we show that when the current through the filament is reduced by the introduction of a semiconductor energy barrier, the method yields, as expected, the ambient temperature both at 5 K and 300 K. This result thus verifies the accuracy and reliability of the temperature extraction method. Moreover, the new structure allows the investigation of the entire current range of interest by modulating the thickness of the semiconductor barrier layer.