Size dependent optical properties of Si quantum dots in Si-rich nitride/Si<inf>3</inf>N<inf>4</inf> superlattice synthesized by magnetron sputtering

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Journal Article
Journal of Applied Physics, 2011, 109 (6)
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A spectroscopic ellipsometry compatible approach is reported for the optical study of Si quantum dots (QDs) in Si-rich nitride/silicon nitride (SRN/Si3N4) superlattice, which based on Tauc-Lorentz model and Bruggeman effective medium approximation. It is shown that the optical constants and dielectric functions of Si QDs are strongly size dependent. The suppressed imaginary dielectric function of Si QDs exhibits a single broad peak analogous to amorphous Si, which centered between the transition energies E 1 and E2 of bulk crystalline Si and blue shifted toward E2 as the QD size reduced. A bandgap expansion observed by the TL model when the size of Si QD reduced is in good agreement with the PL measurement. The bandgap expansion with the reduction of Si QD size is well supported by the first-principles calculations based on quantum confinement. © 2011 American Institute of Physics.
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