The accurate extraction and the reliable, repeatable reduction of graphene–metal contact resistance (R_C) are still open issues in graphene technology. Here, the importance of following clear protocols when extracting R_C using the transfer length method (TLM) is demonstrated. The example of back‐gated graphene TLM structures with nickel contacts, a complementary metal oxide semiconductor compatible metal, is used here. The accurate extraction of R_C is significantly affected by generally observable Dirac voltage shifts with increasing channel lengths in ambient conditions. R_C is generally a function of the carrier density in graphene. Hence, the position of the Fermi level and the gate voltage impact the extraction of R_C. Measurements in high vacuum, on the other hand, result in dependable extraction of R_C as a function of gate voltage owing to minimal spread in Dirac voltages. The accurate measurement and extraction of important parameters like contact‐end resistance, transfer length, sheet resistance of graphene under the metal contact, and specific contact resistivity as a function of the back‐gate voltage is further assessed. The presented methodology has also been applied to devices with gold and copper contacts, with similar conclusions.

We here report a joint experimental and theoretical analysis of polarization switching in ferroelectric tunnel junctions. Our results show that the injection and trapping of charge into the ferroelectric-dielectric stack has a large influence on the polarization switching. Our results are relevant to the physical understanding and to the design of the devices, and for both memory and memristor applications.

An in–house modeling framework for Ferroelectric Tunnelling Junctions (FTJ) is here presented in details. After a precise calibration again experiments, the model is exploited for an insightful study of the design of FTJs as synaptic devices for neuromorphic networks. Our analysis explains and addresses the tradeoff between the reading efficiency and the effects of the depolarization field during the retention phase. The reported results show that a moderately low- $\kappa $ tunnelling dielectric (e.g., SiO ₂ ) can increase the read current and the current dynamic range. The study shows also how the contribution of trapped charge may favor the stabilization of the polarization inside the FTJ, but also reduces the maximum read current.

In this work, we present a clear evidence, based on numerical simulations and experiments, that the polarization compensation due to trapped charge strongly influences the ON/ OFF ratio in Hf _0.5 Zr _0.5 O ₂ (HZO)-based ferroelectric tunnel junctions (FTJs). Furthermore, we identify and explain compensation conditions that enable an optimal operation of FTJs. Our results provide both key physical insights and design guidelines for the operation of FTJs as multilevel synaptic devices.