Journal
ACS NANO
Volume 8, Issue 2, Pages 1222-1230Publisher
AMER CHEMICAL SOC
DOI: 10.1021/nn404013d
Keywords
topological insulators; bismuth selenide; band gap; chemical vapor deposition; quantum dots
Categories
Funding
- NSF [ECCS-1351424]
- Northeastern University Provost's Interdisciplinary seed grant
- US Department of Energy, Office of Science, Basic Energy Sciences [DE-FG02-07ER46352]
- NERSC super-computing center through DOE [DE-AC02-05CH11231]
- Directorate For Engineering
- Div Of Electrical, Commun & Cyber Sys [1351424] Funding Source: National Science Foundation
Ask authors/readers for more resources
Bismuth selenide (Bi2Se3) is a 3D topological insulator, its strong spin orbit coupling resulting in the well-known topologically protected coexistence of gapless metallic surface states and semiconducting bulk states with a band gap, E-g similar or equal to 300 meV. A fundamental question of considerable importance is how the electronic properties of this material evolve under nanoscale confinement We report on catalyst-free, high-quality single-crystalline Bi2Se3 with controlled lateral sizes and layer thicknesses that could be tailored down to a few nanometers and a few quintuple layers (QLs), respectively. Energy-resolved photoabsorption spectroscopy (1.5 eV < E-photon < 6 eV) of these samples reveals a dramatic evolution of the photon absorption spectra as a function of size, transitioning from a featureless metal-like spectrum in the bulk (corresponding to a visually gray color), to one with a remarkably large band gap (E-g >= 2.5 eV) and a spectral shape that correspond to orange-red colorations in the smallest samples, similar to those seen in semiconductor nanostructures. We analyze this colorful transition using ab initio density functional theory and tight-binding calculations which corroborate our experimental findings and further suggest that while purely 2D sheets of few QL-thick Bi2Se3 do exhibit small band gaps that are consistent with previous ARPES results, the presently observed large gaps of a few electronvolts can only result from a combined effect of confinement in all three directions.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available