Analogous to the unique spectral fingerprint of any atom or molecule, researchers have measured the spectrum of optical excitations in monolayer tungsten diselenide (WSe2), which is a member of a new family of ultrathin semiconductors that are just one atomic layer thick.
Scientists discovered how to tune the optical properties of atomically-thin semiconductors, which will aid the design of future microscopic light sensors.
Scientists begin to fill in the blanks on transition metal dichalcogenides.
Studies of the magnetotransport of strongly interacting 2D holes in high mobility, gated, GaAs quantum wells have been carried out a very low temperatures to search for possible anisotropy in the field-induced re-entrant insulating phase. The latter phase was observed in the resistivity at a magnetic field that depended on hole density but that was independent of current direction. This shows that the re-entrant insulating phase is not due to a proposed anisotropic stripe order, but is instead caused by Wigner crystallization.
Black Phosphorus is a layered semiconducting material that can be thinned down to produce atomically thin crystals. These resulting crystals produce a two-dimensional electron gas 2DEG from the resulting quantum confinement of the electrons. Significant differences exist between the physical properties of the atomically thin crystals versus that of the bulk crystals. Zhang and co-workers were able to observe quantum oscillations in black phosphorus allowing the characteristics of the 2DEG in atomically thin crystals to be elucidated.
Using optical spectroscopy and the MagLab’s unique 60 tesla long-pulse magnet in Los Alamos, scientists have shown how nitrogen dopant atoms in gallium arsenide (GaAs) can form extended “supercluster” states or can break up into localized nitrogen clusters. Nitrogen-doped GaAs (GaAs1-xNx) is a semiconductor alloy with potential applications for a wide range of energy-related applications such as photovoltaics.
Superfluorescence, historically, is the spontaneous emission of light from a collection of excited atoms. Scientists visiting the MagLab recently discovered superfluorescence for the first time in a solid material, by shining an extremely brief pulse of light on a layered semiconductor located in an intense magnetic field. In response, superfluorescent light of a different color was emitted thirty trillionths of a second later. Superfluorescence can be used to produce light of any desired color and could be enhanced to occur at room temperature and without magnetic fields. Superfluorescent devices would be powerful tools for optical communications.