. . . . . . . . . .    ANM 2010     3rd International Conference on Advanced Nano Materials     12-15 September 2010 - Agadir, Morocco Back    Abstract ANMM228 MBE GROWN NANOWIRES: HETEROSTRUCTURES, DOPING MECHANISMS AND PHOTOVOLTAIC APPLICATIONS Anna Fontcuberta i Morral Ecole Polytechnique Federale de Lausanne . Nanowires represent model systems for studying a variety of low dimensional phenomena as well as building blocks for the future generation of nanoscale devices. The most exploited nanowire growth technique is the vapor-liquid-solid (VLS) method, which employs gold as a seed for the growth. Synthesis of nanowires by molecular beam epitaxy (MBE) and without using gold as a catalyst gives the opportunity to study nanowires produced in extremely clean conditions and correlate it with optical and electronic properties. We present the method for growing GaAs nanowires by MBE without using gold as a catalyst. With careful choice of the growth parameters nanowires with length of several microns and diameters in the range of 20 nm up to 120 nm are obtained. Additionally, by changing the growth conditions we have managed to obtain radial and axial heterostructures. For the latter, nanowires zinc-blende/wurtzite heterostructures have shown to exhibit interesting optical properties. In particular, we show how the emission of the nanowire can be tuned from 1.51 eV down to 1.43 eV. Theoretical calculations of the band alignment between wurtzite and zinc-blende GaAs will be presented to explain the results. Finally, we will present the latest developments on the doping of GaAs nanowires by MBE. Doping is an essential property of semiconductors that enables their utilization in functional devices such as transistors and solar cells. We will discuss the doping mechanisms of catalyst-free GaAs nanowires, as well as the fabrication of p-i-n junctions for solar cell applications. . © nanoAC . . . . . . . . . .

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