This is an optical nanocavity made, from top to bottom, of molybdenum disulfide (MoS2), aluminum oxide and aluminum. Credit: University at Buffalo
The future of movies and manufacturing may be in 3D, but electronics and photonics are going 2D semiconducting materials. One of the latest advancements centers on molybdenum disulfide (MoS2), while commonly used in lubricants and steel alloys, is still being explored inoptoelectronics. Recently, engineers placed a single layer of MoS2 molecules on top of a photonic structure called an optical nanocavity made of aluminum oxide and aluminum. (A nanocavity is an arrangement of mirrors that allows beams of light to circulate in closed paths which build things like lasers and optical fibers used for communications.)
The MoS2 nanocavity can increase the amount of light that ultrathin semiconducting materials absorb. In turn, this could help industry to continue manufacturing more powerful, efficient and flexible electronic devices. “The nanocavity we have developed has many potential applications,” says Qiaoqiang Gan, PhD. “It could potentially be used to create more efficient and flexible solar panels, and faster photodetectors for video cameras and other devices. It may even be used to produce H fuel through water splitting more efficiently.”
A single layer of MoS2 is advantageous because unlike another promising two-dimensional material, graphene, its bandgap structure is similar to semiconductors used in LEDs, lasers and solar cells. “In experiments, the nanocavity was able to absorb nearly 70% of the laser we projected on it. Its ability to absorb light and convert that light into available energy could ultimately help industry continue to more energy-efficient electronic devices,” said Haomin Song, a PhD candidate.
Industry has kept pace with the demand for smaller, thinner and more powerful optoelectronic devices, in part, by shrinking the size of the semiconductors used in these devices. A problem for energy-harvesting optoelectronic devices, however, is that these ultrathin semiconductors do not absorb light as well as conventional bulk semiconductors. Therefore, there is an intrinsic tradeoff between the ultrathin semiconductors’ optical absorption capacity and their thickness. The nanocavity, described above, is a potential solution to this issue. http://www.buffalo.edu/news/releases/2016/05/028.html
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