Limits...
Key concepts behind forming-free resistive switching incorporated with rectifying transport properties.

Shuai Y, Ou X, Luo W, Mücklich A, Bürger D, Zhou S, Wu C, Chen Y, Zhang W, Helm M, Mikolajick T, Schmidt OG, Schmidt H - Sci Rep (2013)

Bottom Line: This work reports the effect of Ti diffusion on the bipolar resistive switching in Au/BiFeO3/Pt/Ti capacitor-like structures.The resistive switching needs no electroforming process, and is incorporated with rectifying properties which is potentially useful to suppress the sneak current in a crossbar architecture.Those specific features open a promising alternative concept for nonvolatile memory devices as well as for other memristive devices like synapses in neuromorphic circuits.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054, China.

ABSTRACT
This work reports the effect of Ti diffusion on the bipolar resistive switching in Au/BiFeO3/Pt/Ti capacitor-like structures. Polycrystalline BiFeO3 thin films are deposited by pulsed laser deposition at different temperatures on Pt/Ti/SiO2/Si substrates. From the energy filtered transmission electron microscopy and Rutherford backscattering spectrometry it is observed that Ti diffusion occurs if the deposition temperature is above 600°C. The current-voltage (I-V) curves indicate that resistive switching can only be achieved in Au/BiFeO3/Pt/Ti capacitor-like structures where this Ti diffusion occurs. The effect of Ti diffusion is confirmed by the BiFeO3 thin films deposited on Pt/sapphire and Pt/Ti/sapphire substrates. The resistive switching needs no electroforming process, and is incorporated with rectifying properties which is potentially useful to suppress the sneak current in a crossbar architecture. Those specific features open a promising alternative concept for nonvolatile memory devices as well as for other memristive devices like synapses in neuromorphic circuits.

No MeSH data available.


RBS data revealing that the obvious intermixing of Ti and Pt only occurred in thermally treated Pt(200 nm)/Ti(100 nm)/SiO2/Si-substrates at 650°C.The thermal treatments were the same as applied to sample Si-550 and Si-650 (Figure 2). The arrows mark the energy ranges of backscattering particles for the Ti signal and the Pt signal.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC3713515&req=5

f3: RBS data revealing that the obvious intermixing of Ti and Pt only occurred in thermally treated Pt(200 nm)/Ti(100 nm)/SiO2/Si-substrates at 650°C.The thermal treatments were the same as applied to sample Si-550 and Si-650 (Figure 2). The arrows mark the energy ranges of backscattering particles for the Ti signal and the Pt signal.

Mentions: The arising question is the collapse of contact barrier at the BFO/Pt interface in sample Si-650, where a Schottky contact should also have been formed because of the even higher work function of Pt (5.12–5.93 eV) than that of Au (5.10–5.47 eV). To understand the absence of barrier potential at the BFO/Pt interface in Si-650, the EFTEM elemental maps for Ti are shown in Figure 2 for the cross-sections of sample Si-550 (Figure 2a) and Si-650 (Figure 2b). The orange area with higher brightness shows the distribution of the Ti. In Si-550, the Ti layer below the Pt layer can be clearly distinguished. In contrast, the edge of the Ti layer is obscure in the sample Si-650. And a few Ti ‘strip-like' regions penetrating through the above lying Pt layer are detected, which gives the clear signature that a certain amount of Ti has diffused to the Pt/BFO interface during the growth of BFO at the temperature of 650°C. These results are further confirmed by RBS measurements of the Pt(200 nm)/Ti(100 nm) layers (without BFO deposition) annealed in the PLD chamber under the same conditions as the BFO deposition processes for sample Si-550 and Si-650. The RBS spectra shown in Figure 3 demonstrate that the Ti signal and Pt signal locate separately in the backscattering energy range 511–626 keV and 713–1088 keV, respectively, for the virgin and annealed Pt/Ti layers at 550°C. However, due to the enhanced Ti diffusion, for the Pt/Ti layers annealed at 650°C the Ti and Pt signal merge and clearly evidence intermixing between Ti and Pt layers. Ti concentration at the BFO/ Pt interface of sample Si-650 is determined to be 30% by fitting the RBS spectrum with SIMNRA simulation code45.


Key concepts behind forming-free resistive switching incorporated with rectifying transport properties.

Shuai Y, Ou X, Luo W, Mücklich A, Bürger D, Zhou S, Wu C, Chen Y, Zhang W, Helm M, Mikolajick T, Schmidt OG, Schmidt H - Sci Rep (2013)

RBS data revealing that the obvious intermixing of Ti and Pt only occurred in thermally treated Pt(200 nm)/Ti(100 nm)/SiO2/Si-substrates at 650°C.The thermal treatments were the same as applied to sample Si-550 and Si-650 (Figure 2). The arrows mark the energy ranges of backscattering particles for the Ti signal and the Pt signal.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3713515&req=5

f3: RBS data revealing that the obvious intermixing of Ti and Pt only occurred in thermally treated Pt(200 nm)/Ti(100 nm)/SiO2/Si-substrates at 650°C.The thermal treatments were the same as applied to sample Si-550 and Si-650 (Figure 2). The arrows mark the energy ranges of backscattering particles for the Ti signal and the Pt signal.
Mentions: The arising question is the collapse of contact barrier at the BFO/Pt interface in sample Si-650, where a Schottky contact should also have been formed because of the even higher work function of Pt (5.12–5.93 eV) than that of Au (5.10–5.47 eV). To understand the absence of barrier potential at the BFO/Pt interface in Si-650, the EFTEM elemental maps for Ti are shown in Figure 2 for the cross-sections of sample Si-550 (Figure 2a) and Si-650 (Figure 2b). The orange area with higher brightness shows the distribution of the Ti. In Si-550, the Ti layer below the Pt layer can be clearly distinguished. In contrast, the edge of the Ti layer is obscure in the sample Si-650. And a few Ti ‘strip-like' regions penetrating through the above lying Pt layer are detected, which gives the clear signature that a certain amount of Ti has diffused to the Pt/BFO interface during the growth of BFO at the temperature of 650°C. These results are further confirmed by RBS measurements of the Pt(200 nm)/Ti(100 nm) layers (without BFO deposition) annealed in the PLD chamber under the same conditions as the BFO deposition processes for sample Si-550 and Si-650. The RBS spectra shown in Figure 3 demonstrate that the Ti signal and Pt signal locate separately in the backscattering energy range 511–626 keV and 713–1088 keV, respectively, for the virgin and annealed Pt/Ti layers at 550°C. However, due to the enhanced Ti diffusion, for the Pt/Ti layers annealed at 650°C the Ti and Pt signal merge and clearly evidence intermixing between Ti and Pt layers. Ti concentration at the BFO/ Pt interface of sample Si-650 is determined to be 30% by fitting the RBS spectrum with SIMNRA simulation code45.

Bottom Line: This work reports the effect of Ti diffusion on the bipolar resistive switching in Au/BiFeO3/Pt/Ti capacitor-like structures.The resistive switching needs no electroforming process, and is incorporated with rectifying properties which is potentially useful to suppress the sneak current in a crossbar architecture.Those specific features open a promising alternative concept for nonvolatile memory devices as well as for other memristive devices like synapses in neuromorphic circuits.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054, China.

ABSTRACT
This work reports the effect of Ti diffusion on the bipolar resistive switching in Au/BiFeO3/Pt/Ti capacitor-like structures. Polycrystalline BiFeO3 thin films are deposited by pulsed laser deposition at different temperatures on Pt/Ti/SiO2/Si substrates. From the energy filtered transmission electron microscopy and Rutherford backscattering spectrometry it is observed that Ti diffusion occurs if the deposition temperature is above 600°C. The current-voltage (I-V) curves indicate that resistive switching can only be achieved in Au/BiFeO3/Pt/Ti capacitor-like structures where this Ti diffusion occurs. The effect of Ti diffusion is confirmed by the BiFeO3 thin films deposited on Pt/sapphire and Pt/Ti/sapphire substrates. The resistive switching needs no electroforming process, and is incorporated with rectifying properties which is potentially useful to suppress the sneak current in a crossbar architecture. Those specific features open a promising alternative concept for nonvolatile memory devices as well as for other memristive devices like synapses in neuromorphic circuits.

No MeSH data available.