Semiconductors with appropriate band gaps and high carrier mobilities are in high demand for various electronic device applications. This is why researchers are focusing their efforts on semiconductor 2D materials like phosphole, germanene, and silicene.
Alfa Chemistry is a pioneer in 2D material synthesis research and can provide customers like the world's premier R&D labs as well as universities with unique semiconductor 2D material synthesis services. Our method for creating 2D semiconductor materials is both disciplined and novel, and it has sparked a lot of interest in numerous research areas. You can handle all your semiconductor 2D material needs here. thanks to our superior technical processes and low prices. We are pleased to be able to provide materials that will pave the path for future developments.
Alfa Chemistry's Capabilities
Phosphorene Synthesis
The primary atomic layer that makes up naturally occurring black phosphorus is phosphorene. Vertically stacked layers of phosphole are used to make black phosphorus. Phosphorene has a distinctive hexagonal structure that is vertically inclined and wrinkled.
Fig 1. Puckered hexagonal crystal structure of phosphorene. (Balendhran S, et al. 2015)
The most popular method for producing phosphorene is to exfoliate black phosphorus using mechanical, ultrasonic, or ball milling methods. Plasma has recently been employed as an alternative to the exfoliation process, referred to as "plasma thinning," to create a homogeneous and regulated phosphorene production. In comparison to other approaches such as mechanical exfoliation, this process achieves a high level of atomic layer homogeneity.
- A. Thick phosphorene layes are exfoliated to a SiO2/Si substrate, which is then etched with oxygen plasma.
- B. A phsporous oxide (PxOy) layer forms on top of the phosphorene layer during the oxygen plasma etching process, protecting the underlying phosphene from oxygen and moisture interactions. As the etching period goes on, oxygen plasma diffuses through the PxOy layer and changes the underlying layer to PxOy.
- C. A monolayer of phosphorene with a PxOy layer on top is created after careful control of oxygen plasma etching.
- D. To extend the lifetime of phosphorene, an Al2O3 coating is added after the PxOy layer is physically removed.
Currently, we are effectively using plasma to thin black phosphorus into phosphorene. Our use of oxygen plasma in phosphole thinning not only enables good atomic layer control but also overcomes the instability of phosphorene in the air. This phenomenon is due to the oxygen plasma reacting with the phosphene layer, forming a PxOy passivation layer that protects the underlying phosphene from oxygen and moisture interactions.
Fig 2. Synthesis process for making air-stable phosphorene using oxygen plasma etching of thick phosphorene. (Pei J, et al. 2016)
Germanene and Silylene Synthesis
Germanene and silicene are other emerging single-atom 2D materials similar to phosphole. We typically synthesize these two two-dimensional materials by atomic layer deposition of germanene or silicon under ultra-high vacuum conditions using an optional annealing process. We have not yet achieved plasma-assisted or enabled synthesis of germanene or silicene. This technique is under investigation. For more information on synthesis techniques please contact us to discuss.
References
- Balendhran S, et al. (2015). "Elemental Analogues of Graphene: Silicene, Germanene, Stanene, and Phosphorene." Small. 11(6): 640-652.
- Pei J, et al. (2016). "Elemental Analogues of Graphene: Silicene, Germanene, Stanene, and Phosphorene." Nat. Commun. 7: 10450.
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