Self-rectifying performance in the sandwiched structure of Ag/In-Ga-Zn-O/Pt bipolar resistive switching memory
© Yan et al.; licensee Springer. 2014
Received: 16 July 2014
Accepted: 26 September 2014
Published: 2 October 2014
We reported that the resistive switching of Ag/In-Ga-Zn-O/Pt cells exhibited self-rectifying performance at low-resistance state (LRS). The self-rectifying behavior with reliability was dynamic at elevated temperature from 303 to 393 K. The Schottky barrier originated from the interface between Ag electrode and In-Ga-Zn-O films, identified by replacing Ag electrode with Cu and Ti metals. The reverse current at 1.2 V of LRS is strongly suppressed and more than three orders of magnitude lower than the forward current. The Schottky barrier height was calculated as approximately 0.32 eV, and the electron injection process and resistive switching mechanism were discussed.
The 80-nm-thick In-Ga-Zn-O film was under the ambient pressure of 5 × 10-4 Pa. The In-Ga-Zn-O films was prepared on a Pt substrate by magnetron sputtering technique at a power of 100 W in 0.5 Pa atmosphere of Ar + O2 mixture (Ar/O2 flow rate ratio = 50:25) at 450°C. Then postdeposition annealing process was carried out at 450°C in O2 ambiance for 30 min. Then, Ag, Ti, Cu, and Pt were deposited as top electrodes by direct current (DC) magnetron sputtering using a metal shadow mask. The top electrode with 70 nm in thickness was deposited at room temperature. The base pressure of the sputtering chamber was below 2 × 10-4 Pa, and the working pressure was 3 Pa maintained by a gas mixture of argon. The diameter of the top electrodes was 0.1 mm, and the DC power was 10 W. Keithley 2400 source-measure unit (Keithley Instruments Inc., Cleveland, OH, USA) and probe station were employed to measure the electrical characteristics and switching properties. The bottom electrode Pt was grounded, and voltage sweeps were always applied to the Ag top electrode.
Results and discussion
Figure 1 demonstrates the representative I-V characteristic with 0.18, 0.5, and 1.3 V max voltage sweep range; the rectification effects were observed Figure 1c,d. The direction of the voltage sweep 0 → 1.3 → 0 → -1.3 → 0 V is denoted by the numbered arrows in Figure 1d. A remarkable resistive switching was obtained, and the memory cell can be switched between HRS and LRS reversibly. Moreover, the resistive switching was of bipolar type because a reversal polarity of voltage was applied to the cell for transforming the resistance state. It is worth noting that there is no current jump in HRS or LRS as in Ag/STO and Ag/electrolyte/Pt structure resistive switching devices, in which formation and dissolution of Ag filaments are ascribed for the resistive switching mechanism[13, 14]. In addition, the filaments show localization feature; however, we can find obvious size dependence of current of HRS and LRS. The Ag electrodes with two different areas have 0.1 and 0.3 mm diameters. The resistance of the device is scaling with the area size of the top electrode as shown in the inset of Figure 1d. So, no filaments were formed in our device, and the switching mechanism should be different with the phenomenon of electrolytes, and we would discuss the mechanism in following content. The I-V curve of the voltage sweep -1.6 → 1.6 V was measured after the cell was switched to LRS in the inset of Figure 1d. We can observe the Schottky-diode-like behavior in Ag/In-Ga-Zn-O/Pt memory cell, and the reverse current at -1.2 V of LRS is about more than three orders of magnitude lower than forward current at 1.2 V due to the remarkable suppression by the barrier as shown in Figure 1d.
In conclusion, we fabricated the Ag/In-Ga-Zn-O/Pt structure device by RF magnetron sputtering method in this study. The device exhibited good bipolar resistive switching and superior self-rectifying effect. Schottky diode model was employed to explain the mechanism of the self-rectifying characteristics, and the Schottky barrier height is calculated by measuring the I-V curves and fitting the data at different temperatures. The experimental results confirm that the resistive switching of Ag/In-Ga-Zn-O/Pt structure can become a promising candidate as non-volatile memory devices using in cross-bar structure.
This work was financially supported by National Natural Science Foundation of China under Grant Nos. 61306098, 61475041, and 11374086, the Natural Science Foundation of Hebei Province (E2012201088, E2013201176), and the Science Research Program of University in Hebei Province (ZH2012019).
- Sawa A: Resistive switching in transition metal oxides. Mater Today 2008, 11: 28–36.View ArticleGoogle Scholar
- Kang BS, Ahn SE, Lee MJ, Stefanovich G, Kim KH, Xianyu WX, Lee CB, Park Y, Baek IG, Park BH: High-current-density CuOx/InZnOx thin-film diodes for cross-point memory applications. Adv Mater 2008, 20: 3066–3069. 10.1002/adma.200702932View ArticleGoogle Scholar
- Linn E, Rosezin R, Kuegeler C, Waser R: Complementary resistive switches for passive nanocrossbar memories. Nat Mater 2010, 9: 403–406. 10.1038/nmat2748View ArticleGoogle Scholar
- Nardi F, Balatti S, Larentis S, Ielmini D: Complementary switching in metal oxides: toward diode-less crossbar RRAMs. International Electron Devices Meeting: In Technical Digest; 2011:31.1.1–31.1.4.Google Scholar
- Yang YC, Sheridan P, Lu W: Complementary resistive switching in tantalum oxide-based resistive memory devices. Appl Phys Lett 2012, 100: 203112. 10.1063/1.4719198View ArticleGoogle Scholar
- Tang GS, Zeng F, Chen C, Liu HY, Gao S, Song C, Lin Y, Chen G, Pan F: Programmable complementary resistive switching behaviours of a plasma-oxidised titanium oxide nanolayer. Nanoscale Res Lett 2013, 5: 422–428.View ArticleGoogle Scholar
- Cho B, Kim TW, Song S, Ji Y, Jo M, Hwang H, Jung GY, Lee T: Rewritable switching of one diode-one resistor nonvolatile organic memory devices. Adv Mater 2010, 22: 1228–1232. 10.1002/adma.200903203View ArticleGoogle Scholar
- Lv HB, Li YT, Liu Q, Long S: Self-rectifying resistive-switching device with α-Si/WO3 bilayer. IEEE Electron Device Lett 2013, 34: 229–231.View ArticleGoogle Scholar
- Park S, Jung S, Siddik M, Jo M, Park J, Kim S, Lee W, Shin J, Lee D, Choi G, Woo J, Cha E, Lee BH, Hwang H: Self-formed Schottky barrier induced selector-less RRAM for cross-point memory applications. Phys Status Solidi (RRL) 2012, 6: 454–456. 10.1002/pssr.201206382View ArticleGoogle Scholar
- Sawa A, Fujii T, Kawasaki M, Tokura Y: Hysteretic current-voltage characteristics and resistance switching at a rectifying Ti/Pr0.7Ca0.3MnO3 interface. Appl Phys Lett 2004, 85: 4073–4075. 10.1063/1.1812580View ArticleGoogle Scholar
- Yang MK, Kim DY, Park JW, Lee JK: Resistive switching behavior of Cr-doped SrZrO3 perovskite thin films for random access memory applications. J Korean Phys Soc 2005, 47: 313–316. 10.3938/jkps.47.313View ArticleGoogle Scholar
- Nomura K, Ohta H, Takagi A, Kamiya T, Hirano M, Hosono H: Room-temperature fabrication of transparent flexible thin-film transistors using amorphous oxide semiconductors. Nature 2004, 432: 488–492. 10.1038/nature03090View ArticleGoogle Scholar
- Chiu F-C, Li P-W, Chang W-Y: Reliability characteristics and conduction mechanisms in resistive switching memory devices using ZnO thin films. Nanoscale Res Lett 2012, 7: 178. 10.1186/1556-276X-7-178View ArticleGoogle Scholar
- Yan XB, Li K, Yin J, Xia YD, Guo HX, Chen L, Liu ZG: The resistive switching mechanism of Ag/SrTiO3/Pt memory cells. Electrochemical Solid-State Lett 2010, 13: H87-H89. 10.1149/1.3279689View ArticleGoogle Scholar
- Yan XB, Yin J, Guo HX, Su Y, Xu B, Li HT, Yan DW, Yan DW, Liu ZG: Bipolar resistive switching performance of the nonvolatile memory cells based on (AgI)0.2(Ag2MoO4 )0.8 solid electrolyte films. J Appl Phys 2009, 106: 054501. 10.1063/1.3211293View ArticleGoogle Scholar
- Chen MC, Chang TC, Huang SY, Chen SC, Hu CW, Tsai CT, Sze SM: Bipolar resistive switching characteristics of transparent indium gallium zinc oxide resistive random access memory. Electrochemical Solid-State Lett 2010, 13: H191-H193. 10.1149/1.3360181View ArticleGoogle Scholar
- Kim CH, Jang YH, Hwang HJ, Song CH, Yang YS, Cho JH: Bistable resistance memory switching effect in amorphous InGaZnO thin films. Appl Phys Lett 2010, 97: 062109. 10.1063/1.3479527View ArticleGoogle Scholar
- Wang SY, Cheng BL, Wang C, Dai SY, Lu HB, Zhou YL, Chen ZH, Yang GZ: Reduction of leakage current by Co doping in Pt/Ba0.5Sr0.5TiO3/Nb-SrTiO3 capacitor. Appl Phys Lett 2004, 84: 4116–4118. 10.1063/1.1755421View ArticleGoogle Scholar
- Chiu FC: A review on conduction mechanisms in dielectric films. Adv Mater Sci Eng 2014, 2014: 578168.Google Scholar
- Shin YC, Song J, Kim KM, Choi BJ, Choi S, Lee HJ, Kim GH, Eom T, Hwang CS: (In, Sn)2O3/TiO2/Pt Schottky-type diode switch for the TiO2 resistive switching memory array. Appl Phys Lett 2008, 92: 162904. 10.1063/1.2912531View ArticleGoogle Scholar
- Huang JJ, Kuo CW, Chang WC, Hou TH: Transition of stable rectification to resistive-switching in Ti/TiO2/Pt oxide diode. Appl Phys Lett 2010, 96: 262901. 10.1063/1.3457866View ArticleGoogle Scholar
- Hwang CS, Lee BT, Kang CS, Kim JW, Lee KH, Cho HJ, Horii H, Kim WD, Lee SI, Roh YB, Lee MY: A comparative study on the electrical conduction mechanisms of (Ba0.5Sr0.5)TiO3 thin films on Pt and IrO2 electrodes. J Appl Phys 1998, 83: 3703. 10.1063/1.366595View ArticleGoogle Scholar
- Zuo Q, Long S, Liu Q, Zhang S, Wang Q, Li Y, Wang Y, Liu M: Self-rectifying effect in gold nanocrystal-embedded zirconium oxide resistive memory. J Appl Phys 2009, 106: 073724. 10.1063/1.3236632View ArticleGoogle Scholar
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