Extraction of trap location from random telegraph noise in multi-bit AlO_x Magnetic Tunnel Junctions

Jhen-Yong Hong^1*, Chun-Yen Chen¹, Chun-Ting Lee¹, César González-Ruano², Farkhad G. Aliev²

¹Department of Physics, Tamkang University, New Taipei City, Taiwan
²Depto Fisica de la Materia Condensada, Universidad Autonoma de Madrid, Madrid, Spain

* Presenter:Jhen-Yong Hong, email:jyhong@mail.tku.edu.tw

In this study, random telegraph noise (RTN) measurements were performed on AlO_x magnetic tunneling junctions (MTJs) with four different resistance states. An obvious RTN signal was found at low resistance state (LRS), which was resulted from trapping/de-trapping process during the electron transport through AlO_x barrier. By investigating the bias dependence of RTN fluctuations in time and frequency domains, the capture (τ_c) and emission (τ_e) time constant of vacancy-mediated charge transport through AlO_x barrier were extracted to reveal the dynamics of underlying charge transport mechanism. The analysis indicates that the observed fluctuations could arise from electrically activated oxygen vacancy induced or ionic traps which trigger voltage fluctuations while charge transport through AlO_x barrier, showing a 0.72 nm-deep traps distribution below the top electrode. The findings reveal the complex dynamics involved in transport properties which is helpful to guide optimization in the design and operation of multi-bit memory devices.

Keywords: Magnetic Tunnel Junction (MTJ), Magnetoresistance, Low frequency noise (LFN), Random Telegraph Noise (RTN), Resistive Switching