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HL: Halbleiterphysik

HL 50: Poster II

HL 50.83: Poster

Donnerstag, 30. März 2006, 16:30–19:00, P3

Excitons and band behavior in ultrasmall nanoclusters. — •Anton Grygoriev and Vladimir Litovchenko — V. Lashkarev Institute of Semiconductor Physics NASU 45 Prospect Nauki, Kyiv 03028, Ukraine

We present experimental and theoretically investigation of nanosized effects: transformation of the energetic structure of quantum dots in oxide matrix. Calculations were performed taking into account the electron-hole Coulomb interactions, expanded interface area, leakage of electronic density from quantum dot, increasing the effective mass 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, which lead to very stable exciton (at T room). Dependences of exciton binding energy, work function (electron affinity), effective mass 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 infinite barriers) to the ultrasmall (~1-3 nm) dots. Comparison cluster calculations with revised effective mass approximation prove correctness developed approach up to 1 nm. Using 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 photo and field emission applications