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Switching Behaviors of Graphene-Boron Nitride Nanotube Heterojunctions.

Parashar V, Durand CP, Hao B, Amorim RG, Pandey R, Tiwari B, Zhang D, Liu Y, Li AP, Yap YK - Sci Rep (2015)

Bottom Line: Here we show that the growth of electrically insulating BNNTs on graphene can enable the use of graphene as effective digital switches.A switching ratio as high as 10(5) at a turn-on voltage as low as 0.5 V were recorded.Simulation by density functional theory (DFT) suggests that mismatch of the density of states (DOS) is responsible for these novel switching behaviors.

View Article: PubMed Central - PubMed

Affiliation: Department of Physics, Michigan Technological University, 1400 Townsend Drive, Houghton, Michigan 49931, USA.

ABSTRACT
High electron mobility of graphene has enabled their application in high-frequency analogue devices but their gapless nature has hindered their use in digital switches. In contrast, the structural analogous, h-BN sheets and BN nanotubes (BNNTs) are wide band gap insulators. Here we show that the growth of electrically insulating BNNTs on graphene can enable the use of graphene as effective digital switches. These graphene-BNNT heterojunctions were characterized at room temperature by four-probe scanning tunneling microscopy (4-probe STM) under real-time monitoring of scanning electron microscopy (SEM). A switching ratio as high as 10(5) at a turn-on voltage as low as 0.5 V were recorded. Simulation by density functional theory (DFT) suggests that mismatch of the density of states (DOS) is responsible for these novel switching behaviors.

No MeSH data available.


Distance dependent transport properties on a vertical heterojunction.(a) SEM image of a graphene-BNNT heterojunction as contacted across by two STM probes at conduction distance, d = 1.23 μm. (b,c) The corresponding current-voltage (I-V) characteristics at a series of d. (d,e) Linear and log scale of current flow across the heterojunction as a function of distance, d as extracted from Fig. S8. (f) The source-drain currents across the heterojunction as a function of back gate voltages.
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f2: Distance dependent transport properties on a vertical heterojunction.(a) SEM image of a graphene-BNNT heterojunction as contacted across by two STM probes at conduction distance, d = 1.23 μm. (b,c) The corresponding current-voltage (I-V) characteristics at a series of d. (d,e) Linear and log scale of current flow across the heterojunction as a function of distance, d as extracted from Fig. S8. (f) The source-drain currents across the heterojunction as a function of back gate voltages.

Mentions: The as-grown graphene-BNNT heterojunctions were characterized for their electronic properties at room temperature by using a four-probe scanning tunneling microscopy (4-probe STM) system (see Methods)19. The 4-probe STM system allows us to observe the exact probing locations prior to current-voltage (I-V) measurements with the in situ SEM. Figure 2a shows an upright BNNT grown from the graphene surface. This BNNT was probed by a tungsten STM probe 1, while another STM probe 2 was in contact with the graphene surface. The distance, d, between probe 1 and the vertical graphene-BNNT heterojunction, was controlled by changing the contact point on the BNNT.


Switching Behaviors of Graphene-Boron Nitride Nanotube Heterojunctions.

Parashar V, Durand CP, Hao B, Amorim RG, Pandey R, Tiwari B, Zhang D, Liu Y, Li AP, Yap YK - Sci Rep (2015)

Distance dependent transport properties on a vertical heterojunction.(a) SEM image of a graphene-BNNT heterojunction as contacted across by two STM probes at conduction distance, d = 1.23 μm. (b,c) The corresponding current-voltage (I-V) characteristics at a series of d. (d,e) Linear and log scale of current flow across the heterojunction as a function of distance, d as extracted from Fig. S8. (f) The source-drain currents across the heterojunction as a function of back gate voltages.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4507443&req=5

f2: Distance dependent transport properties on a vertical heterojunction.(a) SEM image of a graphene-BNNT heterojunction as contacted across by two STM probes at conduction distance, d = 1.23 μm. (b,c) The corresponding current-voltage (I-V) characteristics at a series of d. (d,e) Linear and log scale of current flow across the heterojunction as a function of distance, d as extracted from Fig. S8. (f) The source-drain currents across the heterojunction as a function of back gate voltages.
Mentions: The as-grown graphene-BNNT heterojunctions were characterized for their electronic properties at room temperature by using a four-probe scanning tunneling microscopy (4-probe STM) system (see Methods)19. The 4-probe STM system allows us to observe the exact probing locations prior to current-voltage (I-V) measurements with the in situ SEM. Figure 2a shows an upright BNNT grown from the graphene surface. This BNNT was probed by a tungsten STM probe 1, while another STM probe 2 was in contact with the graphene surface. The distance, d, between probe 1 and the vertical graphene-BNNT heterojunction, was controlled by changing the contact point on the BNNT.

Bottom Line: Here we show that the growth of electrically insulating BNNTs on graphene can enable the use of graphene as effective digital switches.A switching ratio as high as 10(5) at a turn-on voltage as low as 0.5 V were recorded.Simulation by density functional theory (DFT) suggests that mismatch of the density of states (DOS) is responsible for these novel switching behaviors.

View Article: PubMed Central - PubMed

Affiliation: Department of Physics, Michigan Technological University, 1400 Townsend Drive, Houghton, Michigan 49931, USA.

ABSTRACT
High electron mobility of graphene has enabled their application in high-frequency analogue devices but their gapless nature has hindered their use in digital switches. In contrast, the structural analogous, h-BN sheets and BN nanotubes (BNNTs) are wide band gap insulators. Here we show that the growth of electrically insulating BNNTs on graphene can enable the use of graphene as effective digital switches. These graphene-BNNT heterojunctions were characterized at room temperature by four-probe scanning tunneling microscopy (4-probe STM) under real-time monitoring of scanning electron microscopy (SEM). A switching ratio as high as 10(5) at a turn-on voltage as low as 0.5 V were recorded. Simulation by density functional theory (DFT) suggests that mismatch of the density of states (DOS) is responsible for these novel switching behaviors.

No MeSH data available.