Indirect optical absorption and origin of the emission from {beta}-FeSi{sub 2} nanoparticles: Bound exciton (0.809 eV) and band to acceptor impurity (0.795 eV) transitions

Journal Article · Sat May 15 00:00:00 EDT 2010 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.3391977· OSTI ID:21476246

Lang, R; Amaral, L ^[1]; Meneses, E A ^[2]

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1. Programa de Pos-Graduacao em Ciencias dos Materiais, PGCIMAT, Instituto de Fisica, UFRGS, Porto Alegre, 15051/91501-970 Rio Grande do Sul (Brazil)
2. Instituto de Fisica Gleb Wataghin, UNICAMP, Campinas, 13083-970 Sao Paulo (Brazil)

We investigated the optical absorption of the fundamental band edge and the origin of the emission from {beta}-FeSi{sub 2} nanoparticles synthesized by ion-beam-induced epitaxial crystallization of Fe{sup +} implanted SiO{sub 2}/Si(100) followed by thermal annealing. From micro-Raman scattering and transmission electron microscopy measurements it was possible to attest the formation of strained {beta}-FeSi{sub 2} nanoparticles and its structural quality. The optical absorption near the fundamental gap edge of {beta}-FeSi{sub 2} nanoparticles evaluated by spectroscopic ellipsometry showed a step structure characteristic of an indirect fundamental gap material. Photoluminescence spectroscopy measurements at each synthesis stage revealed complex emissions in the 0.7-0.9 eV spectral region, with different intensities and morphologies strongly dependent on thermal treatment temperature. Spectral deconvolution into four transition lines at 0.795, 0.809, 0.851, and 0.873 eV was performed. We concluded that the emission at 0.795 eV may be related to a radiative direct transition from the direct conduction band to an acceptor level and that the emission at 0.809 eV derives from a recombination of an indirect bound exciton to this acceptor level of {beta}-FeSi{sub 2}. Emissions 0.851 and 0.873 eV were confirmed to be typical dislocation-related photoluminescence centers in Si. From the energy balance we determined the fundamental indirect and direct band gap energies to be 0.856 and 0.867 eV, respectively. An illustrative energy band diagram derived from a proposed model to explain the possible transition processes involved is presented.

• OSTI ID: 21476246
• Journal Information: Journal of Applied Physics, Vol. 107, Issue 10; Other Information: DOI: 10.1063/1.3391977; (c) 2010 American Institute of Physics; ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ABSORPTION SPECTRA
ANNEALING
CRYSTALLIZATION
DISLOCATIONS
ELECTRONIC STRUCTURE
ELLIPSOMETRY
EV RANGE
EXCITONS
IRON SILICIDES
MORPHOLOGY
NANOSTRUCTURES
PARTICLES
PHOTOLUMINESCENCE
RAMAN SPECTRA
SEMICONDUCTOR MATERIALS
SILICON OXIDES
TRANSMISSION ELECTRON MICROSCOPY
VAPOR PHASE EPITAXY
CHALCOGENIDES
CRYSTAL DEFECTS
CRYSTAL GROWTH METHODS
CRYSTAL STRUCTURE
ELECTRON MICROSCOPY
EMISSION
ENERGY RANGE
EPITAXY
HEAT TREATMENTS
IRON COMPOUNDS
LINE DEFECTS
LUMINESCENCE
MATERIALS
MEASURING METHODS
MICROSCOPY
OXIDES
OXYGEN COMPOUNDS
PHASE TRANSFORMATIONS
PHOTON EMISSION
QUASI PARTICLES
SILICIDES
SILICON COMPOUNDS
SPECTRA
TRANSITION ELEMENT COMPOUNDS