Alejandro Gal´┐Żn

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  Nanowire application: Fabrication and functional    analisys for industrial scale-up

   University of Durham

      The aim of this project is to develop methodologies to produce nanowires at large wafer scale. These nanowires are expected to be fully functional and tailorable by modifying the parameters of the process. The production of these nanowires will be carried out in rigid (silicon) and flexible substrates (polyimide). Additionally, the nanowire production can be patterned on the substrate by different techniques. The production process consists of two main stages: deposition of a thin film and chemical growth of the nanowires.

The deposition of the thin film on the substrates will be done using Atomic Layer Deposition (ALD). This technique consists of a series of continuous pulses of gaseous chemical precursors in a cyclic way. The precursors are pulsed for a certain amount of time in the reaction chamber (Figure 1a) and c)) followed by a purge Figure 1 b) and d)). This way, the precursor are allowed enough time to fully react with the surface, creating an atomic layer of said material. By repeating this four steps a number of times, a continuous thin film is obtained. One of the key parameters of this process is the deposition temperature 

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Figure 1. Schematic of a typical ALD process 

The nanowire chemical growth is done by chemical bath deposition (CBD). This technique consists in submerging the ALD seeded substrate in a chemical solution with a zinc precursor. The seeded layer has to be placed facing downwards so deposition of nanowires in solution is avoided. Figure 2 shows a typical picture of nanowires produced following this methodology. 

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Figure 2. Nanowires produces by ALD and CBD