Scientists from the National University of Singapore reviewed the scientific work conducted so far looking into using black phosphorus for next-generation optoelectronics chips. In the paper, the group assesses progress in different components of the chips, from light detection to laser emission.
"Extending the wavelength from near-infrared to mid-infrared enables more diversified functions beyond communication and computing," said author Kah-Wee Ang. "Sensing is one of the most important potential applications in mid-infrared, as it serves to connect the real world we live in to the virtual system on chip."
Black phosphorus achieves its promising versatility through the various ways it can be manipulated as a 2D material. These features make it attractive for the field of optoelectronics, in which information conveyed using conventional electron-based chips is combined with emerging technology that uses photons to transmit information.
Going beyond thermal imaging uses, mid-infrared technology may be applied to identifying molecular "fingerprints" or using unique features of the mid-infrared wavelengths to analyze 3D structures and motion to distinguish human-made objects from natural ones.
"If we could realize a compact mid-infrared system, we may be able to actualize applications, such as health monitoring and toxic gas detection, with a small chip in a hand-held device," Ang said.
By modifying the number of layers, applying a vertical electric field and introducing chemical doping with relative ease, the material can efficiently tune electron energy levels to a device's desired needs. This precise tuning could be instrumental in the electro-optic modulation that would be required for faster computing and data communication, as well as weak signal detection and spectrum analysis.
Despite its promise, widespread production of atom-thick layers of black phosphorus remains challenging.
"We often rely on exfoliation by tape to obtain thin-film black phosphorus, which is not a fully repeatable process," Ang said. "Large-scale growth, if achieved, would be a breakthrough to advance black phosphorus-based technology."
Ang hopes the review helps cement black phosphorus as an essential material in next-generation optoelectronics devices in the coming years and looks to continue working toward high-performance and compact circuit prototypes.
The article, "Black phosphorus photonics towards on-chip applications," is authored by Li Huang and Kah-Wee Ang. The article will appear in Applied Physics Reviews on July 28, 2020 (DOI: 10.1063/5.0005641). After that date, it can be accessed at https://aip.scitation.org/doi/10.1063/5.0005641.