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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.


HRTEM of LB assembled phosphorene on TEM grids.(a) Thin sheets of phosphorene. Inset (i): Aggregate of thin sheets of phosphorene, (ii): Atomic scale image of nanosheets. (b–e) Selected area electron diffraction patterns. (f) Atomic scale micrograph of phosphorene. (g) Interface between two sheets of phosphorene. Inset (iii): Honeycomb microstructure of phosphorene.
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f3: HRTEM of LB assembled phosphorene on TEM grids.(a) Thin sheets of phosphorene. Inset (i): Aggregate of thin sheets of phosphorene, (ii): Atomic scale image of nanosheets. (b–e) Selected area electron diffraction patterns. (f) Atomic scale micrograph of phosphorene. (g) Interface between two sheets of phosphorene. Inset (iii): Honeycomb microstructure of phosphorene.

Mentions: Further, high resolution transmission electron microscopy (HRTEM) was employed to characterize the LB assembled nanosheets on TEM grids. A detailed electron microscopy study has led to the revelation of several microstructural features in real and reciprocal space. In general a uniform microstructure of phosphorene was discerned throughout in the studied specimen (Fig. 3a). Inset (i) in Fig. 3a elucidates mingling of ultra-fine sheets of phosphorene while inset (ii) shows an enlarged view of few mingled sheets as shown in inset (i), exhibiting the evolution of atomic planes with a regular spacing of about 0.51 nm and 0.18 nm with the miller indices (hkl) of 020 and 112, respectively (crystal structure: orthorhombic, lattice constants: a = 0.331 nm, b = 1.029 nm, c = 0.4302 nm, space group: Cmca, reference: JCPDS card no. 76-1961). A corresponding selected area electron diffraction pattern (SAEDP) from the aggregate of phosphorene nanosheets (inset (i) in Fig. 3a) shows the presence of a set of Debye rings in reciprocal space, as displayed in Fig. 3b. The Debye rings in Fig. 3b corresponds to important planes of orthorhombic crystal structure of phosphorene with hkl indices as 020, 040, 111 (marked on Fig. 3b). A set of SAEDPs recorded from the phosphorene nanosheet (Fig. 3a) elucidates single crystalline electron diffraction patterns, as depicted along [012], [210] and [110] zone axes of orthorhombic crystal structure of phosphorene in Fig. 3c–e. The SAEDPs (Fig. 3c–e) clearly reveals that the individual sheets of phosphorene were well crystallized with the organization of atomic planes in the single crystalline nature with no evidence of structural disorder or oxidation. Figure 3f displays an illustrative example of atomic scale image of phosphorene with the stacking of planes (hkl: 040) corresponding to inter-atomic separation of 0.26 nm. In Fig. 3g, a boundary between two phosphorene sheets (I and II) has been marked with a set of arrows, although both the sheets are aligned with an inter-atomic separation of 0.26 nm. It is interesting to note that a magnified view of phosphorene sheet (marked with white dotted region in Fig. 3g) discerns a honey-comb arrangement of phosphorene (inset (iii) in Fig. 3g) in the microstructure.


Large Area Fabrication of Semiconducting Phosphorene by Langmuir-Blodgett Assembly
HRTEM of LB assembled phosphorene on TEM grids.(a) Thin sheets of phosphorene. Inset (i): Aggregate of thin sheets of phosphorene, (ii): Atomic scale image of nanosheets. (b–e) Selected area electron diffraction patterns. (f) Atomic scale micrograph of phosphorene. (g) Interface between two sheets of phosphorene. Inset (iii): Honeycomb microstructure of phosphorene.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f3: HRTEM of LB assembled phosphorene on TEM grids.(a) Thin sheets of phosphorene. Inset (i): Aggregate of thin sheets of phosphorene, (ii): Atomic scale image of nanosheets. (b–e) Selected area electron diffraction patterns. (f) Atomic scale micrograph of phosphorene. (g) Interface between two sheets of phosphorene. Inset (iii): Honeycomb microstructure of phosphorene.
Mentions: Further, high resolution transmission electron microscopy (HRTEM) was employed to characterize the LB assembled nanosheets on TEM grids. A detailed electron microscopy study has led to the revelation of several microstructural features in real and reciprocal space. In general a uniform microstructure of phosphorene was discerned throughout in the studied specimen (Fig. 3a). Inset (i) in Fig. 3a elucidates mingling of ultra-fine sheets of phosphorene while inset (ii) shows an enlarged view of few mingled sheets as shown in inset (i), exhibiting the evolution of atomic planes with a regular spacing of about 0.51 nm and 0.18 nm with the miller indices (hkl) of 020 and 112, respectively (crystal structure: orthorhombic, lattice constants: a = 0.331 nm, b = 1.029 nm, c = 0.4302 nm, space group: Cmca, reference: JCPDS card no. 76-1961). A corresponding selected area electron diffraction pattern (SAEDP) from the aggregate of phosphorene nanosheets (inset (i) in Fig. 3a) shows the presence of a set of Debye rings in reciprocal space, as displayed in Fig. 3b. The Debye rings in Fig. 3b corresponds to important planes of orthorhombic crystal structure of phosphorene with hkl indices as 020, 040, 111 (marked on Fig. 3b). A set of SAEDPs recorded from the phosphorene nanosheet (Fig. 3a) elucidates single crystalline electron diffraction patterns, as depicted along [012], [210] and [110] zone axes of orthorhombic crystal structure of phosphorene in Fig. 3c–e. The SAEDPs (Fig. 3c–e) clearly reveals that the individual sheets of phosphorene were well crystallized with the organization of atomic planes in the single crystalline nature with no evidence of structural disorder or oxidation. Figure 3f displays an illustrative example of atomic scale image of phosphorene with the stacking of planes (hkl: 040) corresponding to inter-atomic separation of 0.26 nm. In Fig. 3g, a boundary between two phosphorene sheets (I and II) has been marked with a set of arrows, although both the sheets are aligned with an inter-atomic separation of 0.26 nm. It is interesting to note that a magnified view of phosphorene sheet (marked with white dotted region in Fig. 3g) discerns a honey-comb arrangement of phosphorene (inset (iii) in Fig. 3g) in the microstructure.

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.