UCLA

There are many parameters necessary for magnetic tunnel junctions (MTJs) to be commercially competitive with established CMOS memory technologies, and one is the reliability of switching, characterized by the write error rate (WER) parameter. WER is a key requirement particularly for magnetoresistive random access memory (MRAM) applications. For lower energy consumption, better bit density, and higher endurance, electric field controlled devices can be used instead of current controlled spin-torque transfer (STT) switching. This thesis experimentally investigates low WER of voltage controlled MTJs using a large number of write trials. In addition, other parameters of MTJ performance are characterized and investigated, including perpendicular magnetic anisotropy (PMA), the voltage-controlled magnetic anisotropy (VCMA) effect, and critical switching voltage at different device sizes. Experimental WER results for our presently fabricated devices are presented and analyzed. Methods are proposed to further reduce the WER by reducing switching speed, as well as materials optimization of the MTJ to reduce damping factor.