Tunable MoS2 Light Emitters Make Better Chips
CAMBRIDGE, Mass., Sept. 23, 2014 — MoS2-based light emitters have the potential to help create powerful, yet energy efficient optoelectronic chips.
A team at MIT has developed a new theoretical framework for building optoelectronic chips using MoS2 (molybdenum disulfide) as light emitters that are tuned to different optical frequencies, which is integral in the development of optoelectronic chips.
In their experiments, the researchers tuned the emitters by depositing two layers of MoS2 (a direct band gap material) onto a silicon substrate.
The dotted lines outline different layers of MoS2 on a silicon substrate, whose relative orientation determines the wavelength of the light that they emit. Courtesy of MIT.
The top layers were rotated relative to the lower layers, which alters the crystal geometry enough to preserve the band gap. The degree of rotation determined the wavelength of the emitted light.
The researchers were able to demonstrate the relationship between the geometries of the rotated layers, as well as the wavelength and intensity of the light emitted. This light has shown to be “significantly more intense than that produced by most rival technologies,” according to the researchers.
With a multilayer MoS2, adjacent layers offer lower energy states because excited electrons are able to seek the lowest energy possible. This cannot be achieved in a conventional monolayer, as the excited electrons are trapped in the material’s crystal lattice. In addition to the MoS2, there are several other elements clustered together among transition metals.
The researchers’ theoretical framework provides a new model for tuning, and could aid in the search for other efficient materials. This model could be used to further this work, potentially in the development of more efficient thin, flexible, bright color displays and devices.
The research will soon be published in Nano Letters.
For more information, visit: www.mit.edu.
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