Charge and Heat Control in Nanoelectronic Devices
Typ
Examensarbete för kandidatexamen
Bachelor Thesis
Bachelor Thesis
Program
Publicerad
2017
Författare
Johansson, Erik
Max, Jakob
Nilsson, Hampus Renberg
Tabakovic, Selma
Modellbyggare
Tidskriftstitel
ISSN
Volymtitel
Utgivare
Sammanfattning
This study examines thermoelectric properties in nanoelectronic devices, specifically setups known as quantum dots. Thermoelectric effects, the relation between voltage gradients and temperature biases, are investigated. Some useful thermoelectric properties of quantum dots include the ability to extract electrical power from a temperature gradient or transport heat from a cooler region to a warmer, i.e. work as a heat engine or as a heat pump. A quantum dot interacts with its environment through different terminals, e.g. a gate terminal and reservoirs. Quantum dots are an interesting setup for thermoelectric applications due to their ability to change transport properties when exposed to a gate voltage or a change in characteristics of adjoining reservoirs. The aim of this study is to find how the characteristic parameters of a quantum dot can be used to control thermoelectric effects. This is essential knowledge when designing systems where quantum dots are wanted to, for example, extract work from a heat flow. The thermoelectric effects are studied using two different methods, namely the master equation and scattering theory. Heat to work conversion and its efficiency is analysed for a set of quantum dot systems. We find the relations between parameters that makes it possible to use quantum dots to either extract electrical work from a heat bath or cool a part of the system. Furthermore, charge and heat separation is studied in a system consisting of a quantum dot, two reservoirs and a voltage probe. This is useful for managing temperatures in circuits doing electrical work. We find it is possible to separate heat and work, but that it requires a certain asymmetry in the system.
Beskrivning
Ämne/nyckelord
Fysik , Nanoteknik , Nanovetenskap och nanoteknik , Physical Sciences , Nano Technology , Nanoscience & Nanotechnology