Composition dependence of unipolar resistance switching in TaO_x thin films

Abstract

Amorphous TaOx thin films were deposited at different temperatures, and the resistance switching properties of the Pt/TaOx/Pt structure were investigated. X‐ray photoelectron spectroscopy showed that the amount of Ta2O5 in the film decreased and the content of Ta suboxides increased substantially when the growth temperature was increased. Unipolar resistance switching near the anode was stable only for TaOx film grown at room temperature. The experimental results revealed the critical effect of the film composition on the resistance switching behavior of TaOx films. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

The evolution of conducting filaments in forming-free resistive switching Pt/TaOx/Pt structures

“…Kim et al 9 realized forming-free bipolar switching in Pt/CuC/HfO x /Pt structures with an ultrathin HfO x layer. Additionally, forming-free unipolar RS behaviors have been reported in Pt/TaO x /Pt structures by this report's authors 7 and in Al/Al x O y /Al structures by Zhu et al 10 The formingfree RS behaviors presented in these reports are mainly due to the low-resistance initial state of the oxide films used, which can be attributed to metallic gradients such as metals or sub-oxides.…”

“…1 Binary oxides, such as NiO, TiO 2 , and TaO x , have attracted much interest because they can be prepared easily and are compatible with current complementary metal-oxidesemiconductor (CMOS) technology. [2][3][4][5][6][7] Normal RS behavior consists of a SET process [from a high resistance state (HRS) to a low resistance state (LRS) at the set voltage V S ] and a RESET process (from the LRS to the HRS at the reset voltage V R ), each induced by an applied voltage. Switching between the HRS and LRS has been generally explained by the formation and rupture of metallic conducting filaments (CFs) in the oxide materials.…”

Regulation of the forming process and the set voltage distribution of unipolar resistance switching in spin-coated CoFe2O4 thin films

“…The average forming voltage of Pt/CFO-500/Pt was around 20 V with a wide distribution, whereas the forming voltage of most Pt/CFO-700/Pt was about 5 V. The lower initial resistance and forming voltage observed in Pt/CFO-700/Pt could be a result of increased oxygen vacancies and less grain boundaries. In addition to the improved crystallinity evidenced by the XRD result (Figure 1), a higher growth temperature or annealing temperature has been reported to induce a higher oxygen vacancy concentration in oxide thin films prepared by pulsed laser deposition or sol-gel [12,22]. The oxygen vacancies are known to form and migrate predominantly along the grain boundaries [23]; therefore, the existence of more oxygen vacancies and less randomly distributed grain boundaries seems to facilitate the formation of CFs, resulting in a lower forming voltage in CFO-700.…”

Compliance current induced non-reversible transition from unipolar to bipolar resistive switching in a Cu/TaOx/Pt structure

“…In our previous study on the URS behavior of Pt/TaO x /Pt structures, we proposed that the conducting filaments were consisted of Ta sub-oxides formed through the migration of oxygen vacancies in the TaO x thin films under the electric field. 6 In this work, the active Cu top electrode could also involve in the formation of conducting filaments as confirmed through the polarity dependence study of both URS and BRS modes. Figure 3 shows the I-V curves of several switching cycles.…”

“…6,7 The Cu top electrodes were deposited on the TaO x thin film by e-beam evaporation using a 50 Â 50 lm 2 square-shaped shadow mask. Resistive switching measurements were performed at room temperature by using an Agilent B1500A semiconductor parameter analyzer in a DC voltage sweep mode under different setting values of the compliance current (I c ).…”