Connecting Three Atomic Layers Puts Semiconducting Science on Its Edge

Image courtesy of University of Washington Optical microscope image of triangular-shaped metal-diselenide monolayer hetero-structures. The central portion containing molybdenum atoms appears darker than the outer portion with tungsten atoms. Inset is a photoluminescence intensity map showing that the linear junction region along the triangular interface produces enhanced light emission (red region).

The Science

Newswise — A new semiconducting material that is only three atomic layers thick that exhibits electronic properties beyond traditional semiconductors has been developed. Two nano-engineered configurations of the material have shown an enhanced response to light.

The Impact

Layered materials at the atomic limit, where electrons are constrained to two dimensions, can be engineered into electronic structures with unique optical, electronic, and magnetic properties. The new structures are a test bed for theories of low dimensional materials physics, but more practically, the optical manipulation of electron charge and magnetic order can lead to new modes of solar energy conversion and flexible, transparent computation devices.

Summary

A new ultra-thin semiconducting material consists of three atomic layers in an “atomic sandwich” configuration with a heavy metal atom layer between two selenium layers. The material is quasi-two dimensional, just three atoms thick, and exhibits unique properties at junctions. When the material is exposed to light and absorbs photons, excited electrons are created which remain coherently coupled, in unique ways, with the charge “hole” they left behind. Stacking up two “atomic sandwiches” yields coupled excited charge states across the planar interface with the magnetic direction or “spin state” becoming aligned for a large population of electrons. A companion result by the same research group demonstrated a method to make the edge of one metal layer match up with the edge of a second, different metal layer — a linear boundary or “hetero-junction” rather than the more typical planar boundary. Engineered electron spin and charge polarization, as well as transport across or along the interface, might be possible as evidenced by the enhanced photoluminescence signals at these positions.

Funding

Primary support by the DOE Office of Science, Basic Energy Sciences. Some students were supported by graduate student fellowships and doctoral training grants (NSF, EPSRC, HEFCE, and Cottrell Scholar Award). Some researchers were supported by the Hong Kong Research Grant Council, the Croucher Foundation, the Science City Research Alliance and the University of Washington Clean Energy Institute.

Publications

A.M. Jones, H. Yu, J.S. Ross, P. Klement, N.J. Ghimire, J. Yan, D.G. Mandrus, W. Yao, X. Xu, “Spin-layer locking effects in optical orientation of exciton spin in bilayer WSe2.” Nature Physics 10, 130–134 (2014). [DOI: 10.1038/nphys2848]

C. Huang, S. Wu, A.M. Sanchez, J.J.P. Peters, R. Beanland, J.S. Ross, P. Rivera, W. Yao, D.H. Cobden, X. Xu, “Lateral heterojunctions within monolayer MoSe2–WSe2 semiconductors.” Nature Materials 13, 1096–1101 (2014). [DOI: 10.1038/NMAT4064]

Contact Information
Kristin Manke
kristin.manke@science.doe.gov

Media Contact

Kristin Manke newswise

More Information:

http://www.science.doe.gov

All latest news from the category: Materials Sciences

Materials management deals with the research, development, manufacturing and processing of raw and industrial materials. Key aspects here are biological and medical issues, which play an increasingly important role in this field.

innovations-report offers in-depth articles related to the development and application of materials and the structure and properties of new materials.

Back to home

Comments (0)

Write a comment

Newest articles

Lighting up the future

New multidisciplinary research from the University of St Andrews could lead to more efficient televisions, computer screens and lighting. Researchers at the Organic Semiconductor Centre in the School of Physics and…

Researchers crack sugarcane’s complex genetic code

Sweet success: Scientists created a highly accurate reference genome for one of the most important modern crops and found a rare example of how genes confer disease resistance in plants….

Evolution of the most powerful ocean current on Earth

The Antarctic Circumpolar Current plays an important part in global overturning circulation, the exchange of heat and CO2 between the ocean and atmosphere, and the stability of Antarctica’s ice sheets….

Partners & Sponsors