Influence of interface region and surrounding media of quantum dots on exciton binding energy.

Anton A. Grigoriev 1Vladimir G. Litovchenko 2,3

1. V.Lashkaryov Institute of Semiconductor Physics NAS Ukraine (ISP), Nauky prosp., Kyiv 03028, Ukraine
2. Institute of Semiconductor Physics (ISP), Nauki pr., Kyiv 03028, Ukraine
3. Institute of Semiconductor Physics NAS Ukraine, Kyiv, Ukraine


We present theoretically investigation of excitonic effects on the energetic structure of silicon quantum dots in silicon oxide matrix. Calculations were performed taking into account the electron-hole Coulomb interactions, expanded interface area, leakage of electronic density from quantum dot and experimental values of barrier high.
The interactions of electrons and holes are strongly enhanced in ultrasmall “quasiopen” quantum dots because of decreasing effective permittivity caused by influence of dots surrounding media.
Dependences of exciton binding energy, work function (electron affinity) and energy of optical transfers from quantum dot diameter have been obtained. The achieved results demonstrate notably difference to the parameters achieved from well-established idealized case (sharp and infinit barriers) to the ultrasmall (~1.5 nm) dots.
Usage of renewed by us effective media approximation allows us to predict some principal new physical effects, such as negative electron affinity (electrons localization outside the dot), which can be useful for electron field emission applications.
Comparison with recent experimental on Si-nanostructures embeded into SiOx insulator and created in porous surface layer show good quantitative agrrement.
Such structures consider as perspective in consumer optoelectronics and as field emmiter for construction of flat panel displays.


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Presentation: poster at E-MRS Fall Meeting 2005, Symposium I, by Anton A. Grigoriev
See On-line Journal of E-MRS Fall Meeting 2005

Submitted: 2005-05-26 11:34
Revised:   2009-06-07 00:44