Breaking Barriers in Oxide Nanoelectronics: Advancements in In Situ TEM Studies

In today's microelectronic industry, oxide nanoelectronics are at its core. To gain insights into the dynamic processes within these nano electronic devices at the nano and sub-nanometer scale, in situ/operando transmission electron microscopy (TEM) has become a vital research avenue. Recent advancements in the integration of microelectromechanical systems (MEMS) within electron microscopes have made it possible to apply various stimuli to samples directly inside the microscope, including electrical biasing.<br/><br/>However, achieving reliable sample preparation for these experiments using focused ion beam (FIB) techniques has been an intricate challenge. Conventional FIB methods have often led to the inadvertent creation of short circuits along the MEMS platforms and TEM devices during sample attachment and electrical contacting. This has obscured the true performance of these devices.<br/><br/>In this study, our innovative FIB sample preparation protocol overcomes these challenges, allowing for the dependable operation of two-terminal oxide devices within the TEM. We have investigated structural changes in materials like SrTiO3-based memristors, Nb-doped lead zirconate titanate (PNZT) piezoelectric, and BaSrTiO3 ferroelectric, directly correlating these observations with the simultaneous acquisition of current-voltage (I-V) curves. This has facilitated meaningful comparisons with their macroscopic counterparts.<br/><br/>Furthermore, our investigations encompass multi-stimuli experiments, introducing gas nano cells into the equation. Interestingly, we have observed the impact of device oxidation induced by electron beam irradiation that alters the electrical response of a SrTiO3-x and BaSrTiO3-x (BST) tunable dielectric device when subjected to an oxygen-rich environment.<br/><br/>Moreover, a suppression of leakage current in TEM lamella devices exposed to Ar/O2 plasma cleaning has also been investigated. Additionally, the effects of electron beam irradiation on the electrical properties of oxide devices, employing them as a tool for checking sample connectivity through STEM (SE)EBIC techniques, have also been explored. These findings collectively contribute to a more comprehensive understanding of oxide nanoelectronics and their behavior at micro and sub-nanometer scales.<br/><br/>In conclusion, our innovative FIB-based sample preparation technique not only enables the study of nano electronic devices under various stimuli conditions within a TEM environment but also facilitates the direct correlation of electrical properties with structural changes. Moreover, we have introduced the use of gas nano cells for multi-stimuli experiments, further enhancing our ability to probe sample connectivity and uncover microstructural factors influencing current-driven mechanisms.