Characterisation of nanowires by transmission electron microscopy and energy dispersive x-ray analysis – Niels Bohr Institute - University of Copenhagen

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Niels Bohr Institute > Calendar > Activities 2013 > Characterisation of na...

Characterisation of nanowires by transmission electron microscopy and energy dispersive x-ray analysis

This thesis is about measurements carried out on the recent addition to the transmission electron microscope at the H.C.Ørsted Laboratory at the Niels Bohr Institute. The addition is a detector capable of performing Energy Dispersive X-ray analysis, (EDX) of electron induced x-rays. In this work the capabilities of the EDX are tested. I test if it is possible to find local areas in group III-V nanowires with different chemical composition than the rest of the wires. I also test how accurately it is possible to determine the chemical composition of these areas. In addition to testing the EDX addition, the normal capabilities of the transmission electron microscope are also used. I use the transmission electron microscope both to examine wires for stacking faults and to examine the effects of different sizes of gold catalysts on the width of the nanowires. Among the wires examined are a group of wires grown with the core-shell method a method for creating wires with fewer defects, and a group of wires with barriers. There are two types of barriers examined indiumarsenide wires with barriers of pure galliumarsenide and indiumarsenide wires with only 15% gallium in the barriers. The former wires are kinked while the latter are straight. I will show that both types of barriers are detectable with the EDX addition.

Master thesis defence by Rune Steffensen