| Summary: | 碩士 === 國立交通大學 === 電子物理系所 === 102 === Topological insulators have attracted scientists’ attentions for years. It was proposed theoretically that the lead chalcogenides PbX (with X=S. Se, or Te) have a great potential to be topological insulators. In this work, we fabricate field effect transistors of lead sulfide nanowires by electron-beam lithography and thermal evaporation and we study electrical properties. We measured electron transport and field effect characteristics of lead sulfide nanowires at the temperature range from 300 to 80 K. The electron transport measurement shows the semiconducting behavior of lead sulfide nanowires. The model of two dimensional variable-range-hopping describes well the transport data of lead sulfide nanowires. It indicates that the electrons transport is confined on the surface. In addition, the device shows ambipolar gating behaviors at low temperature. Especially, the apparent ambipolar behavior appears at 225K. In the photoresponse measurement, we detected a transition in photoconductance at 225 K , and it could be associated with Debye temperature of PbS nanowires.
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