Synthesis and optical properties of MoS{sub 2} and isomorphous nanoclusters in the quantum confinement regime
- Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States)
Highly crystalline nanoclusters of hexagonal (2H polytype) MoS{sub 2} and several of its isomorphous Mo and W chalcogenides have been synthesized with excellent control over cluster size down to {approximately}2 nm. These clusters exhibit highly structured, bandlike optical absorption and photoluminescence spectra which can be understood in terms of the band-structures for the bulk crystals. Key results of this work include: (1) strong quantum confinement effects with blue shifts in some of the absorption features relative to bulk crystals as large as 4 eV for clusters {approximately}2.5 nm in size, thereby allowing great tailorability of the optical properties; (2) the quasiparticle (or excitonic) nature of the optical response is preserved down to clusters {approx_lt}2.5 nm in size which are only two unit cells thick; (3) the demonstration of the strong influence of dimensionality on the magnitude of the quantum confinement. Specifically, three-dimensional confinement of the carriers produces energy shifts which are over an order of magnitude larger than those due to one-dimensional (perpendicular to the layer planes) confinement emphasizing the two-dimensional nature of the structure and bonding; (4) the observation of large increases in the spin-orbit splittings at the top of the valence band at the K and M points of the Brillouin zone with decreasing cluster size, a feature that reflects quantum confinement as well as possible changes in the degree of hybridization of the electronic orbitals which make up the states at these points; and (5) the observation of photoluminescence due to both direct and surface recombination. Several of these features bode well for the potential of these materials for solar photocatalysis. {copyright} {ital 1997 American Institute of Physics.}
- Research Organization:
- Sandia National Laboratories (SNL), Albuquerque, NM, and Livermore, CA (United States)
- DOE Contract Number:
- AC04-94AL85000
- OSTI ID:
- 530019
- Journal Information:
- Journal of Applied Physics, Vol. 81, Issue 12; Other Information: PBD: Jun 1997
- Country of Publication:
- United States
- Language:
- English
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