Direct measurement of the exciton binding energy and effective masses for charge carriers in organic–inorganic tri-halide perovskites
Nature Physics Springer Nature 11:7 (2015) 582-587
Surface-Effect-Induced Optical Bandgap Shrinkage in GaN Nanotubes.
Nano letters 15:7 (2015) 4472-4476
Abstract:
We investigate nontrivial surface effects on the optical properties of self-assembled crystalline GaN nanotubes grown on Si substrates. The excitonic emission is observed to redshift by ∼100 meV with respect to that of bulk GaN. We find that the conduction band edge is mainly dominated by surface atoms, and that a larger number of surface atoms for the tube is likely to increase the bandwidth, thus reducing the optical bandgap. The experimental findings can have important impacts in the understanding of the role of surfaces in nanostructured semiconductors with an enhanced surface/volume ratio.Reduced Stark shift in three-dimensionally confined GaN/AlGaN asymmetric multi-quantum disks
Optical Materials Express Optica Publishing Group 5:4 (2015) 849-857
Hot carrier relaxation of Dirac fermions in bilayer epitaxial graphene.
Journal of physics. Condensed matter : an Institute of Physics journal 27:16 (2015) 164202
Abstract:
Energy relaxation of hot Dirac fermions in bilayer epitaxial graphene is experimentally investigated by magnetotransport measurements on Shubnikov-de Haas oscillations and weak localization. The hot-electron energy loss rate is found to follow the predicted Bloch-Grüneisen power-law behaviour of T(4) at carrier temperatures from 1.4 K up to ∼100 K, due to electron-acoustic phonon interactions with a deformation potential coupling constant of 22 eV. A carrier density dependence n(e)(-1.5) in the scaling of the T(4) power law is observed in bilayer graphene, in contrast to the n(e)(-0.5) dependence in monolayer graphene, leading to a crossover in the energy loss rate as a function of carrier density between these two systems. The electron-phonon relaxation time in bilayer graphene is also shown to be strongly carrier density dependent, while it remains constant for a wide range of carrier densities in monolayer graphene. Our results and comparisons between the bilayer and monolayer exhibit a more comprehensive picture of hot carrier dynamics in graphene systems.Thiophene-based dyes for probing membranes.
Organic & biomolecular chemistry 13:12 (2015) 3792-3802