2D Phosphorus Semiconductors can be used in Nano- Electronic Devices: Researchers

Two-Dimensional Phosphorus is an ideal candidate for nano-electronic applications, a new study has found.

Small, flexible devices require semiconductors with stable properties. Two-dimensional semiconductors such as those made with the wonder-material graphene are considered to be the future of tiny devices. However, despite its flexibility and strength, graphene and other 2D materials suffer from point defects.

Researchers at the Rice University said that 2D phosphorus is free of such defects and can make a promising candidate for next-generation semiconductors. What's more is that 2D phosphorus isn't just theoretical. Scientists have isolated this 2D structure from exfoliation from black phosphorus.

Semiconductors regulate the flow of electrons in an electronic circuit. All modern devices have silicon-based semi-conductors. The researchers say that phosphorus closely resembles 3D silicon. However, silicon has point-defects that can change its properties, but 2D phosphorus is free of these defects.

In the current study, the researchers compared the properties of 2D phosphorus with that of other 2D metals such as dichalcogenides, a common example of which is molybdenum disulfide.

Molybdenum disulfide, germanium and boron nitride are some of the candidates in the 2D material research now.

In dichalcogenides, atoms of two elements alternate in lockstep. A point defect is created in places where the atoms of the same elements bond. These defects slow down the flow of electrons, researchers said.

Mutiple point defects or grain boundaries make these materials less suitable in circuits.

"Because 2-D phosphorus has only one type of element, its defects do not contain hetero-elemental 'wrong' bonds," said Yuanyue Liu, the paper's first author and a Rice alumnus, now a postdoctoral researcher at the National Renewable Energy Laboratory. "These bonds would not trap or recombine electrons or holes.

"This is a good property for application in solar cells," he said in a news release. "Two-D phosphorus could potentially be used to harvest sunlight, as its band gap matches well with the solar spectrum."

Also, phosphorus can be 'doped', meaning that its properties can be enhanced using foreign atoms. Yakobson said that carbon and zinc can be used to boost positive conductivity, while potassium may increase negative conductivity. The researchers believe that phosphorus can be an ideal anode in batteries.

One major problem is that phosphorus reacts with oxygen. The researchers say that the material must be well-sealed for practical purposes.  

The study is published in the journal Nano Letters. The Department of Energy supported the research.