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Stacked 3D RRAM Array with Graphene/CNT as Edge Electrodes.

Bai Y, Wu H, Wang K, Wu R, Song L, Li T, Wang J, Yu Z, Qian H - Sci Rep (2015)

Bottom Line: The electrical results reveal that the RRAM devices could switch normally with this very thin edge electrode at nanometer scale.Meanwhile, benefited from the asymmetric carrier transport induced by Schottky barrier at metal/CNT and oxide/CNT interfaces, a selector built-in 3D RRAM structure using CNT as edge electrode is successfully fabricated and characterized.Furthermore, the discussion of high array density potential is presented.

View Article: PubMed Central - PubMed

Affiliation: Institute of Microelectronics, Tsinghua University, Beijing, China, 100084.

ABSTRACT
There are two critical challenges which determine the array density of 3D RRAM: 1) the scaling limit in both horizontal and vertical directions; 2) the integration of selector devices in 3D structure. In this work, we present a novel 3D RRAM structure using low-dimensional materials, including 2D graphene and 1D carbon nanotube (CNT), as the edge electrodes. A two-layer 3D RRAM with monolayer graphene as edge electrode is demonstrated. The electrical results reveal that the RRAM devices could switch normally with this very thin edge electrode at nanometer scale. Meanwhile, benefited from the asymmetric carrier transport induced by Schottky barrier at metal/CNT and oxide/CNT interfaces, a selector built-in 3D RRAM structure using CNT as edge electrode is successfully fabricated and characterized. Furthermore, the discussion of high array density potential is presented.

No MeSH data available.


Electrical performance of two-layer 3D Ta2O5-x/TaOy RRAM with graphene edge electrode:(a) Forming process of the cells in top and bottom layer which shows a self -compliance property without external device to limit the currents; (b) typical bipolar resistive switching; (c) retention measurement at 85 °C with 1 V read voltage.
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f3: Electrical performance of two-layer 3D Ta2O5-x/TaOy RRAM with graphene edge electrode:(a) Forming process of the cells in top and bottom layer which shows a self -compliance property without external device to limit the currents; (b) typical bipolar resistive switching; (c) retention measurement at 85 °C with 1 V read voltage.

Mentions: The electrical performance of two-layer 3D Ta2O5-x/TaOy RRAM with graphene edge electrode is shown in Fig. 3. The successful forming operations of both top and bottom layer cells are shown in Fig. 3(a), with a forming voltage of −6 V. Figure 3(b) shows the typical double I-V DC sweeping curves of top and bottom layer cells, with the SET and RESET voltages at −4.5 V and 4.5 V respectively. It shows a self-compliance property without external current limiting device in forming and SET operations. Comparing to pervious 3D RRAM with Pt metal plane as the edge electrode11, graphene edge electrode device has much smaller operation current (μA with graphene edge electrode vs. ~mA with Pt metal plan edge electrode). One possible explanation is that, when the TaOy oxide layer contacts with graphene layer during deposition process, the edge of graphene could be oxidized. The previous studies have shown that, in the graphene/Ta2O5-x/TaOy/graphene system, a certain concentration of epoxide groups were grafted onto the basal plane of graphene24. As a result, the graphene is partially oxidized which increases contact resistance significantly. As a result, a high resistance region is generated at the interface between TaOy and graphene. Serving as an internal resistor, this high resistance region helps control the overshoot current and achieves self-compliance property during SET and forming operations. Figure 3(c) shows the retention test results where both HRS at 100 MΩ and LRS at 10 MΩ could be kept stable for more than 104 s at 85 °C.


Stacked 3D RRAM Array with Graphene/CNT as Edge Electrodes.

Bai Y, Wu H, Wang K, Wu R, Song L, Li T, Wang J, Yu Z, Qian H - Sci Rep (2015)

Electrical performance of two-layer 3D Ta2O5-x/TaOy RRAM with graphene edge electrode:(a) Forming process of the cells in top and bottom layer which shows a self -compliance property without external device to limit the currents; (b) typical bipolar resistive switching; (c) retention measurement at 85 °C with 1 V read voltage.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4562297&req=5

f3: Electrical performance of two-layer 3D Ta2O5-x/TaOy RRAM with graphene edge electrode:(a) Forming process of the cells in top and bottom layer which shows a self -compliance property without external device to limit the currents; (b) typical bipolar resistive switching; (c) retention measurement at 85 °C with 1 V read voltage.
Mentions: The electrical performance of two-layer 3D Ta2O5-x/TaOy RRAM with graphene edge electrode is shown in Fig. 3. The successful forming operations of both top and bottom layer cells are shown in Fig. 3(a), with a forming voltage of −6 V. Figure 3(b) shows the typical double I-V DC sweeping curves of top and bottom layer cells, with the SET and RESET voltages at −4.5 V and 4.5 V respectively. It shows a self-compliance property without external current limiting device in forming and SET operations. Comparing to pervious 3D RRAM with Pt metal plane as the edge electrode11, graphene edge electrode device has much smaller operation current (μA with graphene edge electrode vs. ~mA with Pt metal plan edge electrode). One possible explanation is that, when the TaOy oxide layer contacts with graphene layer during deposition process, the edge of graphene could be oxidized. The previous studies have shown that, in the graphene/Ta2O5-x/TaOy/graphene system, a certain concentration of epoxide groups were grafted onto the basal plane of graphene24. As a result, the graphene is partially oxidized which increases contact resistance significantly. As a result, a high resistance region is generated at the interface between TaOy and graphene. Serving as an internal resistor, this high resistance region helps control the overshoot current and achieves self-compliance property during SET and forming operations. Figure 3(c) shows the retention test results where both HRS at 100 MΩ and LRS at 10 MΩ could be kept stable for more than 104 s at 85 °C.

Bottom Line: The electrical results reveal that the RRAM devices could switch normally with this very thin edge electrode at nanometer scale.Meanwhile, benefited from the asymmetric carrier transport induced by Schottky barrier at metal/CNT and oxide/CNT interfaces, a selector built-in 3D RRAM structure using CNT as edge electrode is successfully fabricated and characterized.Furthermore, the discussion of high array density potential is presented.

View Article: PubMed Central - PubMed

Affiliation: Institute of Microelectronics, Tsinghua University, Beijing, China, 100084.

ABSTRACT
There are two critical challenges which determine the array density of 3D RRAM: 1) the scaling limit in both horizontal and vertical directions; 2) the integration of selector devices in 3D structure. In this work, we present a novel 3D RRAM structure using low-dimensional materials, including 2D graphene and 1D carbon nanotube (CNT), as the edge electrodes. A two-layer 3D RRAM with monolayer graphene as edge electrode is demonstrated. The electrical results reveal that the RRAM devices could switch normally with this very thin edge electrode at nanometer scale. Meanwhile, benefited from the asymmetric carrier transport induced by Schottky barrier at metal/CNT and oxide/CNT interfaces, a selector built-in 3D RRAM structure using CNT as edge electrode is successfully fabricated and characterized. Furthermore, the discussion of high array density potential is presented.

No MeSH data available.