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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.


Characterization of BP crystal and its exfoliated suspension.(a) X-ray diffraction spectra of BP crystal. (b) Raman spectra of the BP crystal. Inset: Optical image of crystal. (c) Scanning electron microscopy of BP revealing its layered structure. Inset: EDX spectra of BP crystal (left) and magnified SEM revealing the presence of sharp edges (right). (d) Tauc plot of exfoliated BP suspension. Inset: Digital image of exfoliated BP suspension. (e) Atomic force microscopic image of the drop-cast nanosheets of exfoliated BP. Inset: Height profile of phosphorene nanosheets.
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f1: Characterization of BP crystal and its exfoliated suspension.(a) X-ray diffraction spectra of BP crystal. (b) Raman spectra of the BP crystal. Inset: Optical image of crystal. (c) Scanning electron microscopy of BP revealing its layered structure. Inset: EDX spectra of BP crystal (left) and magnified SEM revealing the presence of sharp edges (right). (d) Tauc plot of exfoliated BP suspension. Inset: Digital image of exfoliated BP suspension. (e) Atomic force microscopic image of the drop-cast nanosheets of exfoliated BP. Inset: Height profile of phosphorene nanosheets.

Mentions: The red allotrope of phosphorus was first converted into its black allotrope as discussed in the method section. The structure, morphology and elemental analysis of the as-prepared crystal were quantified through X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). Figure 1a shows X-ray diffraction pattern of the crystal which reveals the presence of high intensity peaks corresponding to miller indices (hkl) 020, 040 and 060 planes as assigned by the JCPDS number 76-1961. The d spacing between the hkl planes has been calculated that matches well with the reported values of bulk BP49. Further, the Raman vibrational modes corresponding to A1g, B2g and A2g at 362.3 cm−1, 438.3 cm−1 and 466.2 cm−1 respectively (Fig. 1b) confirms the structure of BP37. In Fig. 1c, the SEM image of the BP crystal clearly shows its layered structure and presence of phosphorus atoms was confirmed by the EDX (inset of Fig. 1c).


Large Area Fabrication of Semiconducting Phosphorene by Langmuir-Blodgett Assembly
Characterization of BP crystal and its exfoliated suspension.(a) X-ray diffraction spectra of BP crystal. (b) Raman spectra of the BP crystal. Inset: Optical image of crystal. (c) Scanning electron microscopy of BP revealing its layered structure. Inset: EDX spectra of BP crystal (left) and magnified SEM revealing the presence of sharp edges (right). (d) Tauc plot of exfoliated BP suspension. Inset: Digital image of exfoliated BP suspension. (e) Atomic force microscopic image of the drop-cast nanosheets of exfoliated BP. Inset: Height profile of phosphorene nanosheets.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f1: Characterization of BP crystal and its exfoliated suspension.(a) X-ray diffraction spectra of BP crystal. (b) Raman spectra of the BP crystal. Inset: Optical image of crystal. (c) Scanning electron microscopy of BP revealing its layered structure. Inset: EDX spectra of BP crystal (left) and magnified SEM revealing the presence of sharp edges (right). (d) Tauc plot of exfoliated BP suspension. Inset: Digital image of exfoliated BP suspension. (e) Atomic force microscopic image of the drop-cast nanosheets of exfoliated BP. Inset: Height profile of phosphorene nanosheets.
Mentions: The red allotrope of phosphorus was first converted into its black allotrope as discussed in the method section. The structure, morphology and elemental analysis of the as-prepared crystal were quantified through X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). Figure 1a shows X-ray diffraction pattern of the crystal which reveals the presence of high intensity peaks corresponding to miller indices (hkl) 020, 040 and 060 planes as assigned by the JCPDS number 76-1961. The d spacing between the hkl planes has been calculated that matches well with the reported values of bulk BP49. Further, the Raman vibrational modes corresponding to A1g, B2g and A2g at 362.3 cm−1, 438.3 cm−1 and 466.2 cm−1 respectively (Fig. 1b) confirms the structure of BP37. In Fig. 1c, the SEM image of the BP crystal clearly shows its layered structure and presence of phosphorus atoms was confirmed by the EDX (inset of Fig. 1c).

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.