Au Nanoparticles as Template for Defect Formation in Memristive SrTiO3 Thin Films

Abstract

We investigated the possibility of tuning the local switching properties of memristive crystalline SrTiO3 thin films by inserting nanoscale defect nucleation centers. For that purpose, we employed chemically-synthesized Au nanoparticles deposited on 0.5 wt%-Nb-doped SrTiO3 single crystal substrates as a defect formation template for the subsequent growth of SrTiO3. We studied in detail the resulting microstructure and the local conducting and switching properties of the SrTiO3 thin films. We revealed that the Au nanoparticles floated to the SrTiO3 surface during growth, leaving behind a distorted thin film region in their vicinity. By employing conductive-tip atomic force microscopy, these distorted SrTiO3 regions are identified as sites of preferential resistive switching. These findings can be attributed to the enhanced oxygen exchange reaction at the surface in these defective regions.

Toward Controlling Filament Size and Location for Resistive Switches via Nanoparticle Exsolution at Oxide Interfaces

“…For example Au nanoparticles were delivered to a Ti-patterned bottom electrode by a porter protein with a Ti binding peptide. [38] In terms of the nanoparticle material, Ag [35,37,39,40] or Au [36,38] have proved to be most popular, though the use of Pt, [23,42] Ru, [29] Cu, [34] or Co [43] has been reported as well. In the case of Ag or Cu nanoparticles, metal ions often migrate into the oxide during operation, actively taking part in the switching mechanism.…”

“…In order to address the challenge of stochastic filament location, several strategies have been put forward to spatially confine filaments either in the switching or electrode materials. These include 1) switching within a single dislocation in SrTiO 3 [9] and in SiGe, [10] 2) fabricating electrodes into tips, [11][12][13][14][15][16][17][18] 3) integrating nanoporous graphene into the switching material, [19][20][21][22] 4) embedding nanoparticles into the switching material, [23][24][25][26][27][28][29][30][31][32][33] 5) introducing nanoparticles at the metal-oxide interface, [34][35][36][37][38][39][40] and 6) engineering the edges of the devices, which has been shown to be industrially viable. [41] These strategies are analyzed in terms of their opportunities, processing challenges and materials universality in Table 1, and summarized through device [35] sketches in Figure 1a.…”

“…Another option is to disperse previously synthesized nanoparticles by spin coating [ 35 ] or electrostatic immobilization by organic aids. [ 36 ] All of these deposition methods, however, leave the particles loose, making particle floating a possibility, and can distort the switching film. [ 36 ] Elaborate anchoring methods have been proposed to fix the nanoparticles to the bottom electrode.…”

“…[ 36 ] All of these deposition methods, however, leave the particles loose, making particle floating a possibility, and can distort the switching film. [ 36 ] Elaborate anchoring methods have been proposed to fix the nanoparticles to the bottom electrode. For example Au nanoparticles were delivered to a Ti‐patterned bottom electrode by a porter protein with a Ti binding peptide.…”

Direct Observation of Structural Deformation Immunity for Understanding Oxygen Plasma Treatment-Enhanced Resistive Switching in HfOx-Based Memristive Devices

“…However, an uncontrolled diameter and number of CFs will cause poor uniformity and reliability of memristive devices. To address this problem, various approaches have been proposed to optimize the RS performance by modulating the growth and rupture of CFs, including device structure design [19,20], operating schemes optimization [21], and materials modulation [22,23].…”