In Situ Biasing STEM Investigation of Mg-Based Electrochemical Ionic Synapses (EIS) Devices

Developing and understanding innovative electronic components are essential for next-generation computing devices. In this work, we used in situ STEM techniques to measure Mg-based electrochemical ionic synapse (EIS) devices with a soft electrolyte layer. We first developed a focused ion beam (FIB) sample preparation procedure to minimize structural damage to the prepared lamella. The thin lamella was then deposited on a TEM chip for dedicated <i>in situ</i> biasing STEM experiments. We observed the dynamics of these Mg-based devices with atomic resolution imaging and spectroscopy when voltage was applied. The electron dose of the STEM probe was adjusted to create minimal structural damage to the device, especially the beam-sensitive electrolyte layer composed of MgF₂. We also demonstrated how electron energy loss spectroscopy can be adjusted to obtain critical information about dynamics in sensitive materials during <i>in situ</i> biasing experiments. This work underlines a pathway to characterize beam-sensitive materials with <i>in situ</i> STEM that can be expanded to a larger class of materials.