Browsing by Author "Kilpi, Olli-Pekka"

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  • Lämpötilan vaikutus TiO2 ohutkalvon rakenteeseen atomikerroskasvatuksessa
    (2012) Kilpi, Olli-Pekka
     Sähkötekniikan korkeakoulu | Bachelor's thesis
  • Planarization of Gallium Arsenide Nanowires
    (2014-10-20) Kilpi, Olli-Pekka
     Sähkötekniikan korkeakoulu | Master's thesis
    In this work gallium arsenide nanowire ensembles were planarized and contacted. These group III-V semiconductor nanowires possess many interesting properties for optoelectronic and electronic devices. However, their reliable integration to functional devices remains one of the major challenges. Vertical integration of the nanowires can be done by fabricating an insulation layer between the top of the nanowires and the substrate before deposition of metal contacts. The aim of this work was to find optimal filling materials for the planarization of different kinds of nanowire structures. Nanowire samples with different diameter and length were used. The aim was to find a material, which creates a void and crack free insulation layer without destroying the nanowires. H-PDMS, parylene and three different polymers, SOG 111, SOG B512 and Accuflo from Honeywell, were used. Structures were characterized by scanning electron microscope, current-voltage and optical measurements. The results showed that B512 and Accuflo were good insulation layers, while other filling materials possessed cracks and voids. In addition, Accuflo destroyed several nanowires, thus only B512 was observed to be a reliable planarization material. Insulation of B512 was confirmed by current-voltage measurements.