ÉPITAXIE SÉLECTIVE ET PROPRIÉTÉS OPTIQUES, ÉLECTRIQUES DES ÎLOTS QUANTIQUES DE GERMANIUM SUR SILICIUM (001)

Abstract : The goal of this thesis consists in the development a new method to obtain Ge quantum dots on Si(001) substrates by selective epitaxial growth (SEG) and in studying theirs optical and electrical properties. Two methods of selective growth were chosen. The first one is SEG of Ge quantum dots on SiO2/Si(001) surfaces prepared by partial thermal desorption. We show that the voids, which are a few hundreds nanometers wide were formed. We obtain one or several Ge dots per void as a function of its dimension. A silicon layer grown selectively prior to deposit the Ge dots has a truncated pyramid shape limited by (113) facets. By monitoring the facets formation, we show that it is possible to form a single Ge dot in a broad void. In the second method, we present our results on selectively grown Ge quantum dots in windows patterned by DUV lithography and RIE etching. The number of Ge dots as well as theirs positions depend not only on window size and shape, but also on the area of the Si layer's apex. We obtain single layer and multiple layers of Ge quantum dots. Optical properties of SEG Ge dots were studied by PL and Raman spectroscopies. In comparison with self-assembled Ge dots, we observe an absence of signal from the Ge wetting layer and a blue shift of the emission line of SEG Ge dots, which is related to a higher confinenement of the carriers. Electrical properties of SEG of Ge dots have been studied via the current-voltage characteristics as a function of temperature of the Schottky diodes and also via an AFM cantilever in contact mode at room temperature.
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Theses
Physics [physics]. Université Paris Sud - Paris XI, 2004. French


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Submitted on : Friday, October 1, 2004 - 12:20:01 PM
Last modification on : Friday, October 1, 2004 - 12:20:01 PM

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Huu Lam Nguyen. ÉPITAXIE SÉLECTIVE ET PROPRIÉTÉS OPTIQUES, ÉLECTRIQUES DES ÎLOTS QUANTIQUES DE GERMANIUM SUR SILICIUM (001). Physics [physics]. Université Paris Sud - Paris XI, 2004. French. <tel-00007011>

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