According to the researchers, the materials make it easier to manipulate excitons – electrons and electron holes bound to each other by an electrostatic force. Excitons, created when a laser is shone onto a semiconductor, can transport energy without transporting net electric charge.
Inside a device, excitons interact with each other and their surroundings, then convert back into light that can be detected by CCDs.
While most of the team’s previous work involved structures based on GaAs, they require temperatures of less than 100K. “Our previous structures were built from thin layers of GaAs deposited on top of a substrate with a particular layer thickness and sequence to ensure the specific properties we wanted,” said Erica Calman, a graduate student at UCSD.
The new devices are built from a set of molybdenum disulphide and hexagonal boron nitride, both a single atom thick. “Our specially designed structures help keep excitons bound more tightly together so they can survive at room temperature,” explains Calman.
“The results of our work suggest we may be able to make new structures work all the way up to room temperature,” said Calman. “We set out to prove that we could control the emission of neutral and charged excitations by voltage, temperature and laser power … and demonstrated just that.”