Study of the Resistive Switching Effect in Chromium Oxide Thin Films by Use of Conductive Atomic Force Microscopy

Abstract

Reversible resistive switching of Cr 2 O 3 films was studied by use of conductive atomic force microscopy. Resistive switching in Cr 2 O 3 films occurs as a result of Ag filament paths formed during electrochemical redox reactions. A large memory density of 100 Tbit/sq. inch was achieved with a small filament diameter of 2.9 nm under the action of a compliance current of 10 nA. A fast switching speed of 10 ns, high scalability, and low set/reset currents suggest that Cr 2 O 3 -based resistive memory is suitable for nanoscale devices.Recent research has shown that resistance switching random access memory (ReRAM) is a promising candidate for nanoscale nonvolatile memory applications. Oxide-based ReRAM structures exploit the functionality of capacitor structures in which the oxide materials, for example perovskite (Cr-doped SrTiO 3 , Cr-doped SrZrO 3 , Pr 0.7 Ca 0.3 MnO 3 , etc.), 1-8 chalcogenide materials (GeSbTe), 9 transition metal oxides (TMOs), or binary oxides (NiO, TiO 2 , CuO x , HfO 2 , ZrO x , ZnO, Nb 2 O 5 , Al 2 O 3 , WO x , CrO x ) 10-18 are sandwiched between two metal electrodes. Choosing a material compatible with CMOS processes is a crucial challenge in current research on ReRAM. Among the different materials used, TMOs have the major advantages of simple fabrication and compatibility with CMOS processes. [19][20][21][22] We have focused on correlation of the switching behavior of oxide films (SrTiO 3 , ZnO, TiO 2 , WO 3 and CrO x ) with crystallinity and electrode material. [5][6][7][8][14][15][16][17] From the perspective of application, the basic requirement for next-generation non-volatile memory is high scalability. Because it has recently been shown that switchable conducting nano-filaments may have potential for realizing high-density devices, filamentary switching in nanoscale devices has attracted much attention. 20-23 Further physical insights into geometrical aspects of conducting filaments, for example their number, size, and location, can be obtained by use of conductive atomic force microscopy (C-AFM). Recently, we reported the switching behavior of CrO x thin films, and that the mechanism of switching was an electrochemical redox reaction. 17 To complement previous work, in this paper we report the progressive appearance of conducting filaments in CrO x thin films during resistance switching, studied by use of C-AFM.Silver and chromium oxide films were fabricated, by use of the DC sputtering technique at room temperature, from metallic Ag and Cr targets, on commercial Pt substrates. Deposition of 100-nmthick chromium oxides was performed in a gaseous mixture of 6% oxygen in argon with the total pressure kept at 7 9 10 À3 Torr. During deposition of the Ag top electrode, in an argon environment at 7 9 10 À3 Torr, a mask was used for top electrode patterning. X-ray photoelectron spectroscopy (XPS) was used to investigate the chemical state of the films. Current-voltage (I-V) measurements were obtained by use of a semiconductor-characterization system (Keithley 4200 SCS) and probe stati...

Surface Functionalization of WO3 Thin Films with (3-Aminopropyl)triethoxysilane and Succinic Anhydride

“…Many publications have reported on the switching materials of Ó 2017 The Minerals, Metals & Materials Society binary oxides (SiO 2 , NiO, TiO 2 , CuO x , HfO 2 , ZrO x , ZnO, Nb 2 O 5 , Al 2 O 3 , WO x ). [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22] In spite of the fact that little has been reported on memristor biosensors, memristive characteristics can be hired for biosensing. [2][3][4][5] The sensor transducer principle for memristive biosensor can be described as follows: the surface-functionalized memristor shows different positions of the current minima for voltage increasing (forward) and decreasing (backward) regimes, unlike the bare nanomaterials (nanowires) that show small voltage gap values in the hysteresis loops.…”