Phosphorene

Among two-dimensional materials, phosphorene is a competitor to graphene because it has a nonzero fundamental band gap that can be modulated by strain and the number of layers in a stack.

It attracted renewed attention[11] because of its potential in optoelectronics and electronics due to its band gap, which can be tuned via modifying its thickness, anisotropic photoelectronic properties and carrier mobility.

Currently, there are two main ways of phosphorene production: scotch-tape-based microcleavage[2] and liquid exfoliation,[8][9] while several other methods are being developed as well.

Phosphorene is then transferred on a Si/SiO2 substrate, where it is then cleaned with acetone, isopropyl alcohol and methanol to remove any scotch tape residue.

Bulk black phosphorene is added to a saturated NaOH/NMP solution, which is further sonicated for 4 hours to conduct liquid exfoliation.

[9] The disadvantage of the current methods includes long sonication time, high boiling point solvents, and low efficiency.

H. Kaur et al.[23] demonstrated the synthesis, interface-driven alignment and subsequent functional properties of few layer semiconducting phosphorene using Langmuir-Blodgett assembly.

This is the first study which provides a straightforward and versatile solution towards the challenge of assembling nanosheets of phosphorene onto various supports and subsequently use these sheets in an electronic device.

Therefore, wet assemblies techniques like Langmuir-Blodgett serves as a very valuable new entry point for the exploration of electronic as well as opto-electronic properties of phosphorene as well as other 2D layered inorganic materials.

[2] A pronounced peak centered at around 1.45 eV suggests the band gap structure in few- or single-layer phosphorene difference from bulk crystals.

[29][30][31][32][33][34] Composed of hygroscopic phosphorus and with extremely high surface-to-volume ratio, phosphorene reacts with water vapor and oxygen assisted by visible light[35] to degrade within the scope of hours.

Phosphorene-based transistor consists of a channel of 1.0 μm and uses few layered phosphorene with a thickness varying from 2.1 to over 20 nm.

Reduction of the total resistance with decreasing gate voltage is observed, indicating the p-type characteristic of phosphorene.

Linear I-V relationship of transistor at low drain bias suggests good contact properties at the phosphorene/metal interface.

Fundamental circuit units including digital inverter, voltage amplifier and frequency doubler have been realized.

Bulk black phosphorus consists of multiple phosphorene sheets
Scotch-tape-based microcleavage synthesis of phosphorene
Liquid exfoliation based synthesis of phosphorene
Phosphorene structure: (a) tilted view, (b) side view, (c) top view. Red (blue) balls represent phosphorus atoms in the lower (upper) layer. [ 20 ]
Laser-assisted exfoliation of black phosphorus in liquid.
Top-view electron micrograph of phosphorene [ 23 ]
AFM images of few-layer phosphorene sheets produced by ultrasonic exfoliation of black phosphorus in N-methyl-2-pyrrolidone and spin-coated onto a SiO 2 /Si substrate. [ 7 ]
AFM of few-layer phosphorene sample continuously taken for 7 days. Phosphorene reacts with oxygen and water to develop liquid phase bubbles. [ 28 ]
Electrical characteristic of a flexible black phosphorus transistor showing an intrinsic cutoff frequency of 20 GHz. [ 38 ]