M.Sc Thesis

M.Sc StudentRecher Shani
SubjectThe Impact of Oxide-Oxide Interfaces in Resistive Switching
DepartmentDepartment of Electrical and Computer Engineering
Supervisor PROFESSOR EMERITUS Yosef Salzman
Full Thesis textFull thesis text - English Version


Recent advances in information technology require the development of novel high performance, high density and low power consumption non-volatile memory devices. The resistive switching random access memory is a potential candidate to replace current flash memory technology. Since the geometry of the resistive switching device is often a simple metal-oxide-metal structure it is quite easily scaled, fabricated and integrated with existing CMOS processes.

Typically, the memory devices consists of an active layer, sandwiched between two, either inert or easily oxidized, electrodes. Resistive switching is based on subtle change in the stoichiometry of a path in the switching layer turning the device from high resistance state to low resistance state and vice versa. Stable switching usually requires an initial forming step, in which a connecting filament would grow, permanently reducing the device resistivity.

The main objective of this work is to further elucidate the role of interfaces, specifically oxide-oxide interfaces, in resistive switching device operation and offer an improved solution to the oxygen vacancy concentration control issue. The research goal is addressed using material characterization and electrical measurements on a series of similarly structured devices with different oxide composition. The electrical measurements were conducted in the sub-forming regime (before a forming step had been performed) that had never been addressed before and reveal novel switching behavior. Measurements in this regime enables better viewing of filament formation as no connecting filament, which masks the influence of any partial filaments, is present.

Measurements in the sub-forming regime are able to reveal the electrode type (inert or oxygen exchange layer) experimentaly, which can not be done easily through other electrical measurements nor material charactrization. As this important attribute is determined by various factors such as fabrication conditions, thermal annealing, material selection and more it is oftern hard to pre-determine the interface type. Thus,  we expect this work to be valuable for further studies of switching in the sub-forming regime, interface identification and oxide-oxide interfaces that will add great insight both in the field of forming and device fabrication.