The effects of TiN top electrode composition (TiN vs Ti-rich TiN) on the resistive switching characteristics of selector-less TiN/TiO x /Ta2O5/TiN resistive random access memory (ReRAM) are investigated. Ti-rich TiN enables TiO x to have a higher concentration of oxygen vacancy and reduce barrier height between top electrode and TiO x . This leads to higher on/off current ratio and lower operation voltage without degradation of non-linearity which is the important factor for selector-less type ReRAM, compared to the stoichiometric TiN resistor stack. Consequently, it is verified that the switching mechanism is hybrid combination of filament formation and redox reaction in switching operation. This work is applicable to both high density and cost-effective ReRAM.

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We report the large-scale assembly of type-switchable field effect transistors (FETs) based on carbon nanotubes (CNTs) and nanoparticles (NPs). In this device, the charges stored in NPs adjacent to ambipolar CNT channels were adjusted to control the carrier type and density in the channels. We demonstrated the real-time reconfiguration of individual FET types and logic circuit functionality. Theoretical simulation of a model system was provided to explain this doping effect. This work takes advantage of the ambipolar properties of CNTs and opens up the possibility to build new types of devices with reconfigurable functionalities.

IntroductionReRAM without selector is essentially desirable compared to other types such as 1D1R, and 1T1R because of high scalability and its simplicity in process. Thus, from that point of view, it is imperative to achieve good switching properties with high non-linearity in selector-less ReRAM. However, non-linearity, On/Off ratio, and operation voltage are complicatedly entangled in tradeoff relationship. In this study, we investigated the effect of non-stoichiometric TiN top electrode on switching behaviors and non-linearity properties of Ta 2 O 5 based ReRAM. As a result, thermodynamic approach has been made in explaining improvement of the amount of oxygen vacancies as well as the change in operation voltage with respect to Ti/N ratio has been scrutinized by measurement of the workfunction of the top electrodes.

Ni-silicide with TiN barrier metal has been demonstrated for NAND flash memory devices with 24 nm technology node as a gate word line. When a TiN layer with 200 Å thickness by physical vapor deposition (PVD) is inserted in the control gate polysilicon, inter-diffusion of Ni and grain growth of NiSi are successfully suppressed. As results, no significant sheet resistance increase is observed even at the narrow gate line with 24nm width and its thermal stability is maintained up to 900 ℃.