University of Twente Student Theses


Imaging of gan-algan high electron mobility transistors

Polders, Kay (2014) Imaging of gan-algan high electron mobility transistors.

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Abstract:Presented here is the research done in course of a Master’s assignment at the Physics of Interfaces and Nanomaterials (PIN) group at the University of Twente, commissioned by NXP Semiconductors. Research is done into the carrier transport mechanism of gallium nitride – aluminium gallium nitride high electron mobility transistors, using titanium alloyed contacts, designed and produced by NXP. Three hypotheses concerning the transport mechanism are put forward, all concerning the formation of titanium nitride. A cross-section of these transistors is fabricated and measured by way of scanning tunnelling microscopy, atomic force microscopy, and current-sensing atomic force microscopy. Additional measurements, done during fabrication and in between other measurements, by way of scanning electron microscopy and helium ion microscopy, showing unknown and as of yet unexplained electric behaviour in the structure, are discussed as well. Determination of the transport mechanism proved unsuccessful as the cross-section was fabricated in atmosphere, causing insurmountable oxide build up on the measured surface, which in turn makes definitively determining the electronic structure of the transistor difficult. However, in investigating this result, interesting electronic properties of the stack in question, as well as the substrate used, are found. Recommendations are done on how to repeat the presented measurements with samples created in situ, preventing oxide build-up, as well as recommendations concerning the fabrication of said samples.
Item Type:Essay (Master)
Faculty:TNW: Science and Technology
Subject:33 physics
Programme:Nanotechnology MSc (60028)
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