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Contribution à l'étude du transport et du stockage de charges dans des structures contenant des nanocristaux de germanium

Abstract : The work reported in this thesis is devoted to electrical characterization of germanium nanocrystals (Ge-ncs) elaborated by dewetting on a silicon dioxide layer which is thermally grown on a doped silicon substrate. The study is divided in two parts:
First, current - voltage (I-V) and capacitance (high frequency; 1 MHz) - voltage (C-V) measurements were performed to characterize nanocrystals capped with amorphous silicon. Hence, Coulomb blockade effect at room temperature has been evidenced for nanocrystals with the smallest (~ 3.5 nm) mean diameter. Both I-V and C-V measurements revealed the charge trapping phenomenon in the nanocrystals. The latter is affected by Ge-ncs average size and density and the effects of these two parameters have been separated thanks to measurements at different temperatures. Accordingly, the temperature depended number of electrons stored in each nanocrystal allowed the determination of a thermal activation energy which was shown to be dependent on the average size (or gap) of nanocrystal.
Secondly, characterization with conductive atomic force microscopy was performed on samples containing uncapped nanocrystals. The effects of Ge-ncs size and density on charge trapping and transport have been studied. NF-EBIC (Near Field - Electron Beam Induced Current) measurements showed the electrical activity of sample surface with uncapped Ge-ncs. Finally, minority carrier diffusion lengths measurements have been made. The results showed that this key parameter is reduced by the presence of Ge-ncs and the enhancement of their density.
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Submitted on : Monday, January 19, 2009 - 4:10:20 PM
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Karim Gacem. Contribution à l'étude du transport et du stockage de charges dans des structures contenant des nanocristaux de germanium. Physique [physics]. Université de Reims - Champagne Ardenne, 2008. Français. ⟨tel-00354362⟩

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