Laser light, defective solids make fast computing devices
doi:10.1038/nindia.2020.55 Published online 31 March 2020
A team of physicists has shown that extremely short pulses of laser light can trigger and control the motion of electrons in solids that have defects1. Such light-induced electron movement could generate a current in solids that emit light.
This knowledge, they say, may be utilised to design fast optical and electronic devices, including high-speed computing devices.
The presence of impurities in solids creates structural defects. It is also possible to artificially create defects in solids by removing atoms. Little is known about how such defects can modify high harmonic generation, a process in which exposure to light makes defect-bearing solids emit flashes of high-frequency light.
The scientists, including physicist Gopal Dixit from the Indian Institute of Technology in Mumbai, India, developed computer-based models that they used to probe what would happen if extremely short pulses of laser are shone on two-dimensional monolayer boron nitride with defects.
The researchers found that electrons with opposite spins contribute to light emission. The electron-electron interactions, they write, manifest differently in boron nitride with defects and in boron nitride without defects.
Next, they created defects by doping boron nitride with carbon atoms. Instead of completely removing a nitrogen atom or a boron atom, they replaced either of these atoms with a carbon atom.
When a single boron atom is replaced by a single carbon atom, the electron movements resemble those of a situation where a nitrogen atom is removed completely from boron nitride. The opposite situation arises when a nitrogen atom is replaced by a carbon atom.
1. Mrudul, M. S. et al. High-harmonic generation from spin-polarised defects in solids. npj Comput. Mater. 6:10 (2020) Doi: 10.1038/s41524-020-0275-z