Black Phosphorus’ Band Gap is Fine Tuned for More Flexibility in Electronic Devices
A research team led by Prof. Keun Su Kim at Pohang University of Science and Technology (POSTECH), also affiliated with the Institute for Basic Science (IBS), is currently making waves in the international science community for its breakthrough in two-dimensional (2-D) materials that can revolutionize the mass production of electronic and optoelectronic devices. The team’s discovery was published in the August edition of Science.
The team successfully tuned black phosphorus’ (BP) band gap which makes it possible to make BP a more efficient semiconductor that is superior to graphene. Although graphene is an extremely thin and lightweight conductor, it has a band gap of zero, making it difficult to use as a semiconductor.
“Graphene is a Dirac semimetal. It’s more efficient in its natural state than black phosphorus but it’s difficult to open its band gap,” explained Prof. Kim. “Therefore we tuned BP’s band gap to resemble the natural state of graphene, a unique state of matter that is different from conventional semiconductors”.
Prof. Kim further explained how his team was able to lower the band gap and move the valence and conductive bands closer together to create a stronger current. “We transferred electrons from the dopant—potassium—to the surface of the black phosphorus, which confined the electrons and allowed us to manipulate this state. Potassium produces a strong electrical field which is what we required to tune the size of the band gap”.
Improving the flexibility and form of BP could prove significant for several sectors including electrical engineers who would be able to adjust the band gap and develop devices with the exact behavior desired.