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Large Area Fabrication of Semiconducting Phosphorene by Langmuir-Blodgett Assembly

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ABSTRACT

Phosphorene is a recently new member of the family of two dimensional (2D) inorganic materials. Besides its synthesis it is of utmost importance to deposit this material as thin film in a way that represents a general applicability for 2D materials. Although a considerable number of solvent based methodologies have been developed for exfoliating black phosphorus, so far there are no reports on controlled organization of these exfoliated nanosheets on substrates. Here, for the first time to the best of our knowledge, a mixture of N-methyl-2-pyrrolidone and deoxygenated water is employed as a subphase in Langmuir-Blodgett trough for assembling the nanosheets followed by their deposition on substrates and studied its field-effect transistor characteristics. Electron microscopy reveals the presence of densely aligned, crystalline, ultra-thin sheets of pristine phosphorene having lateral dimensions larger than hundred of microns. Furthermore, these assembled nanosheets retain their electronic properties and show a high current modulation of 104 at room temperature in field-effect transistor devices. The proposed technique provides semiconducting phosphorene thin films that are amenable for large area applications.

No MeSH data available.


Field effect transistor with LB assembled phosphorene as a conducting channel material.(a) Digital image of the device. (b) Optical image of channel. (c) Magnified optical image showing a connecting nanosheet between source and drain. (d) AFM of the device. Inset: Height profile of nanosheet. (e) Variation of drain current IDS with gate voltage VGS (left y-axis is the linear scale, and right y-axis is the logarithmic scale). (f) Variation of drain current IDS with the drain voltage VDS for different gate voltages VGS.
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f4: Field effect transistor with LB assembled phosphorene as a conducting channel material.(a) Digital image of the device. (b) Optical image of channel. (c) Magnified optical image showing a connecting nanosheet between source and drain. (d) AFM of the device. Inset: Height profile of nanosheet. (e) Variation of drain current IDS with gate voltage VGS (left y-axis is the linear scale, and right y-axis is the logarithmic scale). (f) Variation of drain current IDS with the drain voltage VDS for different gate voltages VGS.

Mentions: To elucidate the semiconducting properties of the material, a FET device was fabricated on doped silicon substrates, having 230 nm of silicon dioxide as a dielectric with gold patterning on top (Fig. 4a). The Si-substrate acts as a gate electrode and controls the channel current between the gold electrodes on top which acts as source and drain. The L-Ex BP nanosheets were assembled on these substrates resulting in a conducting channel between 5 μm wide gold electrodes (Fig. 4b). Further, high magnification optical image of the channel shows bridging between source and drain through a phosphorene sheet (Fig. 4c). The thickness of the deposited phosphorene was determined to be ≈4 nm as revealed by AFM (Fig. 4d). The switching behavior of the FET at room temperature is presented in Fig. 4e. The back gate voltage VGS was swept from −10 V to 0 V, keeping drain voltage VDS at −1 V. The maximum on state drain current IDS is 102 μA/μm while off-state current is 10−2 μA/μm enabling a high on-off current modulation ratio of 104. Figure 4f represents the IDS versus VDS graph for different step voltages of VGS which shows that current in few layer phosphorene FET can be controlled by providing a suitable gate voltage. Comparing this Ion/Ioff ratio with the previous reported values234852, it is evidenced that LB assembly is a suitable and convenient method for the fabrication of superior quality phosphorene thin films.


Large Area Fabrication of Semiconducting Phosphorene by Langmuir-Blodgett Assembly
Field effect transistor with LB assembled phosphorene as a conducting channel material.(a) Digital image of the device. (b) Optical image of channel. (c) Magnified optical image showing a connecting nanosheet between source and drain. (d) AFM of the device. Inset: Height profile of nanosheet. (e) Variation of drain current IDS with gate voltage VGS (left y-axis is the linear scale, and right y-axis is the logarithmic scale). (f) Variation of drain current IDS with the drain voltage VDS for different gate voltages VGS.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5037434&req=5

f4: Field effect transistor with LB assembled phosphorene as a conducting channel material.(a) Digital image of the device. (b) Optical image of channel. (c) Magnified optical image showing a connecting nanosheet between source and drain. (d) AFM of the device. Inset: Height profile of nanosheet. (e) Variation of drain current IDS with gate voltage VGS (left y-axis is the linear scale, and right y-axis is the logarithmic scale). (f) Variation of drain current IDS with the drain voltage VDS for different gate voltages VGS.
Mentions: To elucidate the semiconducting properties of the material, a FET device was fabricated on doped silicon substrates, having 230 nm of silicon dioxide as a dielectric with gold patterning on top (Fig. 4a). The Si-substrate acts as a gate electrode and controls the channel current between the gold electrodes on top which acts as source and drain. The L-Ex BP nanosheets were assembled on these substrates resulting in a conducting channel between 5 μm wide gold electrodes (Fig. 4b). Further, high magnification optical image of the channel shows bridging between source and drain through a phosphorene sheet (Fig. 4c). The thickness of the deposited phosphorene was determined to be ≈4 nm as revealed by AFM (Fig. 4d). The switching behavior of the FET at room temperature is presented in Fig. 4e. The back gate voltage VGS was swept from −10 V to 0 V, keeping drain voltage VDS at −1 V. The maximum on state drain current IDS is 102 μA/μm while off-state current is 10−2 μA/μm enabling a high on-off current modulation ratio of 104. Figure 4f represents the IDS versus VDS graph for different step voltages of VGS which shows that current in few layer phosphorene FET can be controlled by providing a suitable gate voltage. Comparing this Ion/Ioff ratio with the previous reported values234852, it is evidenced that LB assembly is a suitable and convenient method for the fabrication of superior quality phosphorene thin films.

View Article: PubMed Central - PubMed

ABSTRACT

Phosphorene is a recently new member of the family of two dimensional (2D) inorganic materials. Besides its synthesis it is of utmost importance to deposit this material as thin film in a way that represents a general applicability for 2D materials. Although a considerable number of solvent based methodologies have been developed for exfoliating black phosphorus, so far there are no reports on controlled organization of these exfoliated nanosheets on substrates. Here, for the first time to the best of our knowledge, a mixture of N-methyl-2-pyrrolidone and deoxygenated water is employed as a subphase in Langmuir-Blodgett trough for assembling the nanosheets followed by their deposition on substrates and studied its field-effect transistor characteristics. Electron microscopy reveals the presence of densely aligned, crystalline, ultra-thin sheets of pristine phosphorene having lateral dimensions larger than hundred of microns. Furthermore, these assembled nanosheets retain their electronic properties and show a high current modulation of 104 at room temperature in field-effect transistor devices. The proposed technique provides semiconducting phosphorene thin films that are amenable for large area applications.

No MeSH data available.