Solution synthesis of nanostructured transition metal chalcogenides and their electrical and thermal properties
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With the development of electronic devices, more electrical units need to squeeze into small packages. As a result, more heat energy will be produced in the same area and thermal management has become a more critical issue for the design of electrical devices. One protection method is to integrate the thermal switch into an electrical device, and it will cut off current when the temperature is above the operating temperature range. There are significant gaps that must be overcome before the thermal switch can be integrated into an electrical device. The performance requirements include low resistance under normal operation to reduce power consumption while turning into high resistance at the critical condition to cut off or reduce the current. It also should be self-recoverable after cooling down and have a low production cost.
This dissertation first describes a solution-phase synthesis of iron telluride nanostructures with reversible and reproducible switching behavior between p- and n-type conduction. A proof-of-concept thermally triggered p-n diode has been demonstrated. This device has a large electrical conductivity during normal operation which can minimize power consumption. While at high temperature, it will be triggered to a p-n diode with a fast response time to temperature rising. Secondly, a large-scale solution-phase synthesis method to synthesize silver telluride based on tellurium nanowire template has also been developed. Its structural phase transition can be realized by temperature- or electrically-driven method. In addition, the threshold DC voltage is less than 1 V and can result in a sharp drop in conductance. Lastly, A new electromagnetic sensor prototype is presented by sintering electromagnetic absorption material and phase change material together. The electromagnetic absorption material will absorb electromagnetic wave in the X band and increase temperature.