New Slim Semiconductors With Tunable Band Gaps

An international research team led by Chongwu Zhou of the University of Southern California has created a new family of layered, atomically thin black arsenic-phosphorous semiconductors (Adv. Mater. 2015, DOI: 10.1002/adma.201501758). The new materials possess tunable band gaps that span a previously unoccupied regime for atomically thin materials such as graph-ene, hexagonal boron nitride, and black phosphorus. An electronic material’s band gap represents the minimum energy input needed to allow charge carriers to conduct. The band gaps of the black arsenic-phosphorus materials correspond to the energy carried by long-wavelength infrared light and could be useful in applications including light radar (lidar), the team reports. The team created the layered semiconductors by heating arsenic and phosphorus compounds in the presence of a mineralizing agent. The researchers were able to tune the band gap by controlling the ratio of the two elements in the final product. They then peeled off layers of black arsenic-phosphorus crystals using adhesive tape, getting sheets as thin as 1.3 nm.