In 2014, researchers conducted experiments where they exfoliated black phosphorus, or phosphorene, into very thin films of about 10 to 20 atoms thick. Phosphorene, has an inherent bandgap, or energy band in which no electron states can exist, that graphene lacks.
According to Philip Feng, an assistant professor of electrical engineering and computer science at Case Western Reserve University, phosphorene’s bandgap can be fine-tuned by adjusting the number of layers of the material.
“Optoelectronic functions, including light absorption, emission, and modulation, of semiconductor materials depend on the size of the bandgap,” Mo Li, a photonics expert at the University of Minnesota, said.
“Unfortunately, black phosphorus is hard to make and hard to keep. Currently, it’s made by treating an amorphous form of the element called red phosphorus with high pressure (1 gigapascal) and high temperature (1,000 °C). The resulting millimeter-scale crystals are then exfoliated into atoms-thick flakes for making nanostructures and nanoscale devices,” IEEE.org added.
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