Evolution of Phosphorene Sheets through Direct Crystallization of Thin‐Film Red Phosphorus

Abstract

A novel hydrogen plasma treatment to convert an amorphous phosphorus film deposited on silicon substrates into a thin crystalline layer is successfully developed. The amorphous phosphorus layer is deposited on desired substrates as silicon using vacuum evaporation in a direct-current plasma reactor in a controllable fashion. The formation of 2D phosphorene layers is based on the phase transition of a previously deposited amorphous film into the crystalline black phosphorus flakes. Direct transformation from red phosphorus to black can be achieved at a temperature of 300 C on desired substrates as silicon, although mica and glass can also be used. This allotrope transformation can be achieved without any high pressure or high temperature. Apart from hydrogen plasma treatment, ultraviolet (UV) exposure to see any possible improvement in the 2D layer formation is also used herein. Various characterization techniques including scanning electron microscopy, transmission electron microscopy, atomic force microscopy, and Raman spectroscopy are used to study the crystallinity and morphology of the samples. In addition, the plasma-treated flakes are used to realize photodetectors which show excellent response to illuminating light. While the hydrogen plasma treatment leads to crystalline phosphorene sheets, the UV treatment results in granular and partially crystalline nanostructures.The world of 2D materials has witnessed a growing path to apply this appealing family in various applications including electronics, optoelectronics, bioelectronics, and sensing and energy devices. [1][2][3][4][5] Owing to its unique properties, phosphorene (few layers or monolayers of black phosphorus (BP)) has grasped the researchers' attention around the globe. [6,7] High-pressure and high-temperature procedures, sonication-based methods, and even phase transition using the presence of SnI 4 /Sn are the most common techniques used to realize few-or monolayer phosphorene through a complete phase transition from red phosphorus (RP) to its BP allotrope. Mechanical exfoliation of phosphorene flakes and their transfer to desired substrates is a main line of research for the fabrication of phosphorenebased electronic and optical devices. Owing to an unstable and sensitive nature of phosphorene, its successful transfer onto the target substrate is a challenge and requires extreme precautions to avoid extended exposure to air and humidity. [8][9][10][11][12][13] Direct formation of the crystalline phosphorene flakes on desired substrates has always been a technological challenge. Recently various bottom-up techniques have been demonstrated to realize 2D materials including phosphorene flakes. As reported, there is no successful fabrication of phosphorene by means of the chemical vapor deposition (CVD) technique or wet chemical methods. The most successful bottom-up method which has been introduced recently is pulsed laser deposition (PLD) which requires a bulk target. [14] Accordingly, the evolution of a bottom-up growth method, which does not nee...

Linker-free Functionalization of Phosphorene Nanosheets by Sialic Acid Biomolecules

“…The formation of phosphorene sheets is based on our previously reported direct crystallization and thinning of red phosphorus layers and their conversion into phosphorene nanosheets. 33 Figure 1 depicts the procedure used in this experiment. The hydrogen-assisted direct crystallization of amorphous phosphorus into phosphorene nanosheets allows the P-atoms on each side of the sheet to be highly reactive and make covalent bindings with the available sites of biomolecules.…”

“…The formation of phosphorene sheets is based on our previously reported direct crystallization and thinning of red phosphorus layers and their conversion into phosphorene nanosheets Figure depicts the procedure used in this experiment.…”

Experimental and molecular dynamics studies of an ultra-fast sequential hydrogen plasma process for fabricating phosphorene-based sensors

“…Deposition of an initial red phosphorus layer is the first step of the crystallization, leading to the formation of an amorphous layer directly on silicon substrates. As in our previous work 32 , 0.1 g of RP powder (Merck ≥ 97%, Hohenbrunn, Germany) with a handy-press apparatus is needed to prepare a RP tablet. Silicon substrates and RP tablet are placed in a plasma reactor (dc-PECVD) to deposit the desired layer onto substrates.…”

Polymorphism in Post-Dichalcogenide Two-Dimensional Materials

“…As a result, efforts at the synthesis of phosphorene have mostly focused on the conversion of thin films of red phosphorus to the black phosphorus structure. This polymorphic conversion typically requires high pressures and recent attempts have yielded thick films or thick nanoflakes, rather than the desired continuous monolayer. − Rajabali et al avoided the high pressure pathway by instead using plasma treatment at 300 °C to crystallize red phosphorus films into thick black phosphorus nanoflakes . Meanwhile, synthesis of hb -P has been limited to MBE on Au(111), where the typical substrate temperature during deposition is between 180 and 350 °C. ,, The lack of reports of hb -P on other substrates suggest that film–substrate interactions are the dominant factor in realizing this phase as is discussed later in section .…”

“…257−259 Rajabali et al avoided the high pressure pathway by instead using plasma treatment at 300 °C to crystallize red phosphorus films into thick black phosphorus nanoflakes. 260 Meanwhile, synthesis of hb-P has been limited to MBE on Au (111), where the typical substrate temperature during deposition is between 180 and 350 °C. 200,250,261 The lack of reports of hb-P on other substrates suggest that film− substrate interactions are the dominant factor in realizing this phase as is discussed later in section 2.3.2.2.…”